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Bibliography on: Wolbachia

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ESP: PubMed Auto Bibliography 15 Jul 2020 at 01:36 Created: 


WIKIPEDIA: Wolbachia is a genus of bacteria which "infects" (usually as intracellular symbionts) arthropod species, including a high proportion of insects, as well as some nematodes. It is one of the world's most common parasitic microbes and is possibly the most common reproductive parasite in the biosphere. Its interactions with its hosts are often complex, and in some cases have evolved to be mutualistic rather than parasitic. Some host species cannot reproduce, or even survive, without Wolbachia infection. One study concluded that more than 16% of neotropical insect species carry bacteria of this genus, and as many as 25 to 70 percent of all insect species are estimated to be potential hosts. Wolbachia also harbor a temperate bacteriophage called WO. Comparative sequence analyses of bacteriophage WO offer some of the most compelling examples of large-scale horizontal gene transfer between Wolbachia coinfections in the same host. It is the first bacteriophage implicated in frequent lateral transfer between the genomes of bacterial endosymbionts. Gene transfer by bacteriophages could drive significant evolutionary change in the genomes of intracellular bacteria that were previously considered highly stable or prone to loss of genes overtime. Outside of insects, Wolbachia infects a variety of isopod species, spiders, mites, and many species of filarial nematodes (a type of parasitic worm), including those causing onchocerciasis ("River Blindness") and elephantiasis in humans as well as heartworms in dogs. Not only are these disease-causing filarial worms infected with Wolbachia, but Wolbachia seem to play an inordinate role in these diseases. A large part of the pathogenicity of filarial nematodes is due to host immune response toward their Wolbachia. Elimination of Wolbachia from filarial nematodes generally results in either death or sterility of the nematode.

Created with PubMed® Query: wolbachia NOT pmcbook NOT ispreviousversion

Citations The Papers (from PubMed®)


RevDate: 2020-07-10

Nguyen HM, Theppannga W, Vongphayloth K, et al (2020)

Screening of ectoparasites from domesticated dogs for bacterial pathogens in Vientiane, Lao PDR.

Zoonoses and public health [Epub ahead of print].

Arthropod-borne diseases are widespread worldwide and are a complex interaction between animals, humans and ectoparasites. The understanding of the diversity and epidemiology of organisms transmitted by arthropod vectors, and the role of hosts and vectors in transmission of infections remain limited in Lao PDR. What knowledge does exist is primarily focused on more rural regions of the country. This study screened ectoparasites from domestic dogs in Vientiane city for the presence of bacterial pathogens of zoonotic importance. A total of 3,511 arthropod vectors were collected from 112 dogs. Vectors collected were Rhipicephalus sanguineus ticks, Ctenocephalides felis felis and Ctenocephalides felis orientis fleas and Heterodoxus spiniger lice. A sub-sample of vectors from each dog was analysed by PCR to identify the potential bacteria. From 129 vector pools, Rickettsia spp. was detected in 6.7% (7/105) pools of ticks, 86.4% (19/22) pools of fleas and both pools of lice. Sequencing analysis confirmed Rickettsia felis in 13 flea pools and one louse pool and Rickettsia asembonensis in six flea pools. Anaplasmataceae was identified in 14.3% (15/105) tick pools and 100% (22/22) flea pools. Sequencing revealed the presence of Anaplasma platys in ticks and Wolbachia pipientis in fleas. Leptospira spp. was detected in one tick and one louse pool, and Brucella spp. was detected in 12.4% (13/105) tick pools. All samples were negative for Bartonella spp., Coxiella burnetii and Borrelia burgdorferi. This is the first study providing evidence of R. asembonensis in fleas in Laos. Results from this study show arthropods are potential vectors to transmit zoonotic infection in Vientiane city, suggesting humans are at risk of zoonotic infections in the city.

RevDate: 2020-07-10

Félix ML, Armúa-Fernández MT, Parodi P, et al (2020)

Detection of a putative novel genotype of Anaplasma in gray-brocket deer (Mazama gouazoubira) from Uruguay.

Experimental & applied acarology pii:10.1007/s10493-020-00523-0 [Epub ahead of print].

Anaplasmataceae includes the genera Anaplasma, Ehrlichia, Neorickettsia and Wolbachia, comprising a group of obligate intracellular bacteria. The genus Anaplasma has pathogenic species transmitted by ticks of veterinary and human health importance. Wild ungulates such as deer represent important reservoirs and amplifiers of Anaplasmataceae. The interaction between deer and domestic ruminants represents a serious problem due to the transmission of these pathogens through their ectoparasites. In the present study, we investigated the presence of Anaplasmataceae organisms in blood, tissues and tick samples of a gray-brocket deer (Mazama gouazoubira). The specimen was found dead in a farm in northeast Uruguay. PCRs targeting partial regions of 16S rRNA and groESL genes were carried out for Anaplasmataceae DNA detection. Moreover, several ectoparasites were identified: the chewing louse Tricholipeurus albimarginatus, the Neotropical deer louse fly Lipoptena mazamae, and the ticks Haemaphysalis juxtakochi and Rhipicephalus microplus. A consensus sequence of 1274 bp of 16S rRNA was generated for Anaplasma sp. from the M. gouazoubira blood sample. All ticks analysed by PCR assays were negative. No band was detected in any of the samples after PCR targeting groESL gene. Phylogenetic analysis using 16S rRNA partial gene sequences, clustered the putative novel genotype sequence obtained in this study, named Anaplasma sp. genotype Mazama-Uruguay, along with Anaplasma sp. detected in Mazama sp., Mazama americana and Mazama bororo, all deer species from Brazil. Furthermore, this cluster showed to be closely related to Anaplasma bovis sequences obtained from various ruminants and other mammals from several parts of the world. The pathogenicity as well as its infecting potential to other cervids or domestic ruminants is currently unknown. Further studies should be performed in order to characterize this novel species, especially targeting other genes.

RevDate: 2020-07-09

Brady OJ, Kharisma DD, Wilastonegoro NN, et al (2020)

The cost-effectiveness of controlling dengue in Indonesia using wMel Wolbachia released at scale: a modelling study.

BMC medicine, 18(1):186 pii:10.1186/s12916-020-01638-2.

BACKGROUND: Release of virus-blocking Wolbachia-infected mosquitoes is an emerging disease control strategy that aims to control dengue and other arboviral infections. Early entomological data and modelling analyses have suggested promising outcomes, and wMel Wolbachia releases are now ongoing or planned in 12 countries. To help inform government, donor, or philanthropist decisions on scale-up beyond single city releases, we assessed this technology's cost-effectiveness under alternative programmatic options.

METHODS: Using costing data from existing Wolbachia releases, previous dynamic model-based estimates of Wolbachia effectiveness, and a spatially explicit model of release and surveillance requirements, we predicted the costs and effectiveness of the ongoing programme in Yogyakarta City and three new hypothetical programmes in Yogyakarta Special Autonomous Region, Jakarta, and Bali.

RESULTS: We predicted Wolbachia to be a highly cost-effective intervention when deployed in high-density urban areas with gross cost-effectiveness below $1500 per DALY averted. When offsets from the health system and societal perspective were included, such programmes even became cost saving over 10-year time horizons with favourable benefit-cost ratios of 1.35 to 3.40. Sequencing Wolbachia releases over 10 years could reduce programme costs by approximately 38% compared to simultaneous releases everywhere, but also delays the benefits. Even if unexpected challenges occurred during deployment, such as emergence of resistance in the medium-term or low effective coverage, Wolbachia would remain a cost-saving intervention.

CONCLUSIONS: Wolbachia releases in high-density urban areas are expected to be highly cost-effective and could potentially be the first cost-saving intervention for dengue. Sites with strong public health infrastructure, fiscal capacity, and community support should be prioritised.

RevDate: 2020-07-08

Liu G, Tan FH, Lau SA, et al (2020)

Lactic acid bacteria feeding reversed the malformed eye structures and ameliorated gut microbiota profiles of Drosophila melanogaster Alzheimer's Disease model.

Journal of applied microbiology [Epub ahead of print].

AIMS: To utilize transgenic GMR-Aβ42 Drosophila melanogaster as a model to evaluate potential Alzheimer's disease (AD)-reversal effects via the administration of lactic acid bacteria (LAB) strains, and associations of LAB with changes in gut microbiota profiles.

METHODS AND RESULTS: Wild type flies (Oregon-R) was crossed with glass multimer reporter-GAL4 (GMR-GAL4) to produce GMR-OreR (Control), while UAS-Aβ42 (#33769) crossed with GMR-GAL4 to produce transgenic Drosophila line that expressed Aβ42 (GMR-Aβ42). Feed containing seven different LAB strains (Lactobacillus paracasei 0291, Lactobacillus helveticus 1515, Lactobacillus reuteri CDV, Lactobacillus reuteri 8513d, Lactobacillus fermentum 8312, Lactobacillus casei Y, Lactobacillus sakei Probio65) were given to GMR-Aβ42 respectively, while feed without LAB strains were given to control and transgenic GMR-Aβ Drosophila lines. The morphology of the eyes was viewed with scanning electron microscopy (SEM). The changes in gut microbiota profiles associated with LAB were analyzed using 16s high throughput sequencing. Malformation of eye structures in transgenic GMR-Aβ42 Drosophila were reversed upon the administration of LAB strains, with more prevalent effects from Lactobacillus sakei Probio65 and Lactobacillus paracasei 0291. The GMR-Aβ group showed dominance of Wolbachia in the gut, a genus that was almost absent in the normal control group (P<0.05). The administration of L. sakei Probio65 and L. paracasei 0291 reduced the abundance of Wolbachia accompanied by increased abundance of Stenotrophomonas and Acetobacter (P<0.05), resembling the microbial profile of the control group.

CONCLUSIONS: L. sakei Probio65 and L. paracasei 0291 have more prominent effects in reversing malformed eye of transgenic GMR-Aβ42 Drosophila, and reducing the abundance of Wolbachia accompanied by an increased abundance of Stenotrophomonas and Acetobacter.

Potentials of LAB to prevent and/or alleviate the onset and pathogenesis of neurodegenerative diseases such as AD, supporting brain health strategies along the gut-brain axis.

RevDate: 2020-07-08

Gunderson EL, Vogel I, Chappell L, et al (2020)

The endosymbiont Wolbachia rebounds following antibiotic treatment.

PLoS pathogens, 16(7):e1008623 pii:PPATHOGENS-D-20-00474 [Epub ahead of print].

Antibiotic treatment has emerged as a promising strategy to sterilize and kill filarial nematodes due to their dependence on their endosymbiotic bacteria, Wolbachia. Several studies have shown that novel and FDA-approved antibiotics are efficacious at depleting the filarial nematodes of their endosymbiont, thus reducing female fecundity. However, it remains unclear if antibiotics can permanently deplete Wolbachia and cause sterility for the lifespan of the adult worms. Concerns about resistance arising from mass drug administration necessitate a careful exploration of potential Wolbachia recrudescence. In the present study, we investigated the long-term effects of the FDA-approved antibiotic, rifampicin, in the Brugia pahangi jird model of infection. Initially, rifampicin treatment depleted Wolbachia in adult worms and simultaneously impaired female worm fecundity. However, during an 8-month washout period, Wolbachia titers rebounded and embryogenesis returned to normal. Genome sequence analyses of Wolbachia revealed that despite the population bottleneck and recovery, no genetic changes occurred that could account for the rebound. Clusters of densely packed Wolbachia within the worm's ovarian tissues were observed by confocal microscopy and remained in worms treated with rifampicin, suggesting that they may serve as privileged sites that allow Wolbachia to persist in worms while treated with antibiotic. To our knowledge, these clusters have not been previously described and may be the source of the Wolbachia rebound.

RevDate: 2020-07-08

Rosenwald LC, Sitvarin MI, JA White (2020)

Endosymbiotic Rickettsiella causes cytoplasmic incompatibility in a spider host.

Proceedings. Biological sciences, 287(1930):20201107.

Many arthropod hosts are infected with bacterial endosymbionts that manipulate host reproduction, but few bacterial taxa have been shown to cause such manipulations. Here, we show that a bacterial strain in the genus Rickettsiella causes cytoplasmic incompatibility (CI) between infected and uninfected hosts. We first surveyed the bacterial community of the agricultural spider Mermessus fradeorum (Linyphiidae) using high throughput sequencing and found that individual spiders can be infected with up to five different strains of maternally inherited symbiont from the genera Wolbachia, Rickettsia, and Rickettsiella. The Rickettsiella strain was pervasive, found in all 23 tested spider matrilines. We used antibiotic curing to generate uninfected matrilines that we reciprocally crossed with individuals infected only with Rickettsiella. We found that only 13% of eggs hatched when uninfected females were mated with Rickettsiella-infected males; in contrast, at least 83% of eggs hatched in the other cross types. This is the first documentation of Rickettsiella, or any Gammaproteobacteria, causing CI. We speculate that induction of CI may be much more widespread among maternally inherited bacteria than previously appreciated. Further, our results reinforce the importance of thoroughly characterizing and assessing the inherited microbiome before attributing observed host phenotypes to well-characterized symbionts such as Wolbachia.

RevDate: 2020-07-07

Faria Waziry PA, Raja A, Salmon C, et al (2020)

Impact of pyriproxyfen on virus behavior: implications for pesticide-induced virulence and mechanism of transmission.

Virology journal, 17(1):93 pii:10.1186/s12985-020-01378-y.

BACKGROUND: More than 3 years since the last Zika virus (ZIKV) outbreak in Brazil, researchers are still deciphering the molecular mechanisms of neurovirulence and vertical transmission, as well as the best way to control spread of ZIKV, a flavivirus. The use of pesticides was the main strategy of mosquito control during the last ZIKV outbreak.

METHODS: We used vesicular stomatitis virus (VSV) tagged with green fluorescent protein (GFP) as our prototypical virus to study the impact of insecticide pyriproxyfen (PPF). VZV-GFP infected and uninfected Jurkat, HeLa and trophoblast cells were treated with PPF and compared to untreated cells (control). Cell viability was determined by the MTT assay. Cell morphology, presence of extracellular vesicles (EVs), virus infection/GFP expression as well as active mitochondrial levels/localization were examined by confocal microscopy.

RESULTS: PPF, which was used to control mosquito populations in Brazil prior to the ZIKV outbreak, enhances VSV replication and has cell membrane-altering properties in the presence of virus. PPF causes enhanced viral replication and formation of large EVs, loaded with virus as well as mitochondria. Treatment of trophoblasts or HeLa cells with increasing concentrations of PPF does not alter cell viability, however, it proportionately increases Jurkat cell viability. Increasing concentrations of PPF followed by VSV infection does not interfere with HeLa cell viability. Both Jurkats and trophoblasts show proportionately increased cell death with increased concentrations of PPF in the presence of virus.

CONCLUSIONS: We hypothesize that PPF disrupts the lipid microenvironment of mammalian cells, thereby interfering with pathways of viral replication. PPF lowers viability of trophoblasts and Jurkats in the presence of VSV, implying that the combination renders immune system impairment in infected individuals as well as enhanced vulnerability of fetuses towards viral vertical transmission. We hypothesize that similar viruses such as ZIKV may be vertically transmitted via EV-to-cell contact when exposed to PPF, thereby bypassing immune detection. The impact of pesticides on viral replication must be fully investigated before large scale use in future outbreaks of mosquito borne viruses.

RevDate: 2020-07-07

Khoo JJ, Kurtti TJ, Husin NA, et al (2020)

Isolation and Propagation of Laboratory Strains and a Novel Flea-Derived Field Strain of Wolbachia in Tick Cell Lines.

Microorganisms, 8(7): pii:microorganisms8070988.

Wolbachia are intracellular endosymbionts of several invertebrate taxa, including insects and nematodes. Although Wolbachia DNA has been detected in ticks, its presence is generally associated with parasitism by insects. To determine whether or not Wolbachia can infect and grow in tick cells, cell lines from three tick species, Ixodes scapularis, Ixodes ricinus and Rhipicephalus microplus, were inoculated with Wolbachia strains wStri and wAlbB isolated from mosquito cell lines. Homogenates prepared from fleas collected from cats in Malaysia were inoculated into an I. scapularis cell line. Bacterial growth and identity were monitored by microscopy and PCR amplification and sequencing of fragments of Wolbachia genes. The wStri strain infected Ixodes spp. cells and was maintained through 29 passages. The wAlbB strain successfully infected Ixodes spp. and R. microplus cells and was maintained through 2-5 passages. A novel strain of Wolbachia belonging to the supergroup F, designated wCfeF, was isolated in I. scapularis cells from a pool of Ctenocephalides sp. cat fleas and maintained in vitro through two passages over nine months. This is the first confirmed isolation of a Wolbachia strain from a flea and the first isolation of any Wolbachia strain outside the "pandemic" A and B supergroups. The study demonstrates that tick cells can host multiple Wolbachia strains, and can be added to panels of insect cell lines to improve success rates in isolation of field strains of Wolbachia.

RevDate: 2020-07-03

Lebov JF, Mattick J, Libro S, et al (2020)

Complete Genome Sequence of wBp, the Wolbachia Endosymbiont of Brugia pahangi FR3.

Microbiology resource announcements, 9(27): pii:9/27/e00480-20.

Lymphatic filariasis is a devastating disease caused by filarial nematode roundworms, which contain obligate Wolbachia endosymbionts. Here, we assembled the genome of wBp, the Wolbachia endosymbiont of the filarial nematode Brugia pahangi, from Illumina, Pacific Biosciences, and Oxford Nanopore data. The complete, circular genome is 1,072,967 bp.

RevDate: 2020-07-03

Duan XZ, Sun JT, Wang LT, et al (2020)

Recent infection by Wolbachia alters microbial communities in wild Laodelphax striatellus populations.

Microbiome, 8(1):104 pii:10.1186/s40168-020-00878-x.

BACKGROUND: Host-associated microbial communities play an important role in the fitness of insect hosts. However, the factors shaping microbial communities in wild populations, including genetic background, ecological factors, and interactions among microbial species, remain largely unknown.

RESULTS: Here, we surveyed microbial communities of the small brown planthopper (SBPH, Laodelphax striatellus) across 17 geographical populations in China and Japan by using 16S rRNA amplicon sequencing. Using structural equation models (SEM) and Mantel analyses, we show that variation in microbial community structure is likely associated with longitude, annual mean precipitation (Bio12), and mitochondrial DNA variation. However, a Wolbachia infection, which is spreading to northern populations of SBPH, seems to have a relatively greater role than abiotic factors in shaping microbial community structure, leading to sharp decreases in bacterial taxon diversity and abundance in host-associated microbial communities. Comparative RNA-Seq analyses between Wolbachia-infected and -uninfected strains indicate that the Wolbachia do not seem to alter the immune reaction of SBPH, although Wolbachia affected expression of metabolism genes.

CONCLUSION: Together, our results identify potential factors and interactions among different microbial species in the microbial communities of SBPH, which can have effects on insect physiology, ecology, and evolution. Video Abstract.

RevDate: 2020-07-02
CmpDate: 2020-07-02

Caragata EP, Tikhe CV, G Dimopoulos (2019)

Curious entanglements: interactions between mosquitoes, their microbiota, and arboviruses.

Current opinion in virology, 37:26-36.

Mosquitoes naturally harbor a diverse community of microorganisms that play a crucial role in their biology. Mosquito-microbiota interactions are abundant and complex. They can dramatically alter the mosquito immune response, and impede or enhance a mosquito's ability to transmit medically important arboviral pathogens. Yet critically, given the massive public health impact of arboviral disease, few such interactions have been well characterized. In this review, we describe the current state of knowledge of the role of microorganisms in mosquito biology, how microbial-induced changes to mosquito immunity moderate infection with arboviruses, cases of mosquito-microbial-virus interactions with a defined mechanism, and the molecular interactions that underlie the endosymbiotic bacterium Wolbachia's ability to block virus infection in mosquitoes.

RevDate: 2020-07-01

Lefoulon E, Clark T, Borveto F, et al (2020)

Pseudoscorpion Wolbachia symbionts: diversity and evidence for a new supergroup S.

BMC microbiology, 20(1):188 pii:10.1186/s12866-020-01863-y.

BACKGROUND: Wolbachia are the most widely spread endosymbiotic bacteria, present in a wide variety of insects and two families of nematodes. As of now, however, relatively little genomic data has been available. The Wolbachia symbiont can be parasitic, as described for many arthropod systems, an obligate mutualist, as in filarial nematodes or a combination of both in some organisms. They are currently classified into 16 monophyletic lineage groups ("supergroups"). Although the nature of these symbioses remains largely unknown, expanded Wolbachia genomic data will contribute to understanding their diverse symbiotic mechanisms and evolution.

RESULTS: This report focuses on Wolbachia infections in three pseudoscorpion species infected by two distinct groups of Wolbachia strains, based upon multi-locus phylogenies. Geogarypus minor harbours wGmin and Chthonius ischnocheles harbours wCisc, both closely related to supergroup H, while Atemnus politus harbours wApol, a member of a novel supergroup S along with Wolbachia from the pseudoscorpion Cordylochernes scorpioides (wCsco). Wolbachia supergroup S is most closely related to Wolbachia supergroups C and F. Using target enrichment by hybridization with Wolbachia-specific biotinylated probes to capture large fragments of Wolbachia DNA, we produced two draft genomes of wApol. Annotation of wApol highlights presence of a biotin operon, which is incomplete in many sequenced Wolbachia genomes.

CONCLUSIONS: The present study highlights at least two symbiont acquisition events among pseudoscorpion species. Phylogenomic analysis indicates that the Wolbachia from Atemnus politus (wApol), forms a separate supergroup ("S") with the Wolbachia from Cordylochernes scorpioides (wCsco). Interestingly, the biotin operon, present in wApol, appears to have been horizontally transferred multiple times along Wolbachia evolutionary history.

RevDate: 2020-07-01

Kirik H, Tummeleht L, Lilja T, et al (2020)

Novel Mitochondrial DNA Lineage Found among Ochlerotatus communis (De Geer, 1776) of the Nordic-Baltic Region.

Insects, 11(6): pii:insects11060397.

The Ochlerotatus (Oc.) communis complex consist of three Northern American species as well as a common Holarctic mosquito (Diptera: Culicidae) Oc. communis (De Geer, 1776). These sister species exhibit important ecological differences and are capable of transmitting various pathogens, but cannot always be differentiated by morphological traits. To investigate the Oc. communis complex in Europe, we compared three molecular markers (COI, ND5 and ITS2) from 54 Estonian mosquitoes as well as two COI marker sequences from Sweden. These sequences were subjected to phylogenetic analysis and screened for Wolbachia Hertig and Wolbach symbionts. Within and between groups, distances were calculated for each marker to better understand the relationships among individuals. Results demonstrate that a group of samples, extracted from adult female mosquitoes matching the morphology of Oc. communis, show a marked difference from the main species when comparing the mitochondrial markers COI and ND5. However, there is no variance between the same specimens when considering the nuclear ITS2. We conclude that Oc. communis encompasses two distinct mitochondrial DNA lineages in the Nordic-Baltic region. Further research is needed to investigate the origin and extent of these genetic differences.

RevDate: 2020-06-30

Herran B, Geniez S, Delaunay C, et al (2020)

The shutting down of the insulin pathway: a developmental window for Wolbachia load and feminization.

Scientific reports, 10(1):10551 pii:10.1038/s41598-020-67428-1.

Using the isopod Armadillidium vulgare as a case study, we review the significance of the "bacterial dosage model", which connects the expression of the extended phenotype to the rise of the Wolbachia load. In isopods, the Insulin-like Androgenic Gland hormone (IAG) induces male differentiation: Wolbachia feminizes males through insulin resistance, presumably through defunct insulin receptors. This should prevent an autocrine development of the androgenic glands so that females differentiate instead: feminization should translate as IAG silencing and increased Wolbachia load in the same developmental window. In line with the autocrine model, uninfected males expressed IAG from the first larval stage on, long before the androgenic gland primordia begin to differentiate, and exponentially throughout development. In contrast in infected males, expression fully stopped at stage 4 (juvenile), when male differentiation begins. This co-occurred with the only significant rise in the Wolbachia load throughout the life-stages. Concurrently, the raw expression of the bacterial Secretion Systems co-increased, but they were not over-expressed relative to the number of bacteria. The isopod model leads to formulate the "bacterial dosage model" throughout extended phenotypes as the conjunction between bacterial load as the mode of action, timing of multiplication (pre/post-zygotic), and site of action (soma vs. germen).

RevDate: 2020-06-29

Ferreira AG, Fairlie S, LA Moreira (2020)

Insect vectors endosymbionts as solutions against diseases.

Current opinion in insect science, 40:56-61 pii:S2214-5745(20)30078-X [Epub ahead of print].

Viral diseases transmitted by mosquitoes, known as arboviruses, pose a significant threat to human life and are a major burden on many health systems around the world. Currently, arbovirus control strategies rely on insecticides or vector source reduction and, in the absence of effective, accessible and affordable vaccines, mainly on symptomatic based, non-specific treatments. However, insecticides have the potential to interfere with non-target organisms, cause environmental toxicity and insecticide resistance reduces their effectiveness as a sustainable control method. Complementary and sustainable strategies are urgently needed. Wolbachia, an invertebrate endosymbiont, has been used as an alternative strategy for arboviral control, through suppression or modification of mosquito populations. Here we discuss the burden that arboviruses impose on human populations and how Wolbachia can be used as a sustainable strategy for control, in alignment with the United Nations- 2030 Agenda for Sustainable Development.

RevDate: 2020-06-30

Liu Y, Guo Z, El Smaily M, et al (2020)

A Wolbachia infection model with free boundary.

Journal of biological dynamics, 14(1):515-542.

Scientists have been seeking ways to use Wolbachia to eliminate the mosquitoes that spread human diseases. Could Wolbachia be the determining factor in controlling the mosquito-borne infectious diseases? To answer this question mathematically, we develop a reaction-diffusion model with free boundary in a one-dimensional environment. We divide the female mosquito population into two groups: one is the uninfected mosquito population that grows in the whole region while the other is the mosquito population infected with Wolbachia that occupies a finite small region. The mosquito population infected with Wolbachia invades the environment with a spreading front governed by a free boundary satisfying the well-known one-phase Stefan condition. For the resulting free boundary problem, we establish criteria under which spreading and vanishing occur. Our results provide useful insights on designing a feasible mosquito releasing strategy that infects the whole mosquito population with Wolbachia and eradicates the mosquito-borne diseases eventually.

RevDate: 2020-06-26

Ajene IJ, Khamis FM, van Asch B, et al (2020)

Microbiome diversity in Diaphorina citri populations from Kenya and Tanzania shows links to China.

PloS one, 15(6):e0235348 pii:PONE-D-20-04601.

The Asian citrus psyllid (Diaphorina citri) is a key pest of Citrus spp. worldwide, as it acts as a vector for "Candidatus Liberibacter asiaticus (Las)", the bacterial pathogen associated with the destructive Huanglongbing (HLB) disease. Recent detection of D. citri in Africa and reports of Las-associated HLB in Ethiopia suggest that the citrus industry on the continent is under imminent threat. Endosymbionts and gut bacteria play key roles in the biology of arthropods, especially with regards to vector-pathogen interactions and resistance to antibiotics. Thus, we aim to profile the bacterial genera and to identify antibiotic resistance genes within the microbiome of different populations worldwide of D. citri. The metagenome of D. citri was sequenced using the Oxford Nanopore full-length 16S metagenomics protocol, and the "What's in my pot" (WIMP) analysis pipeline. Microbial diversity within and between D. citri populations was assessed, and antibiotic resistance genes were identified using the WIMP-ARMA workflow. The most abundant genera were key endosymbionts of D. citri ("Candidatus Carsonella", "Candidatus Profftella", and Wolbachia). The Shannon diversity index showed that D. citri from Tanzania had the highest diversity of bacterial genera (1.92), and D. citri from China had the lowest (1.34). The Bray-Curtis dissimilarity showed that China and Kenya represented the most diverged populations, while the populations from Kenya and Tanzania were the least diverged. The WIMP-ARMA analyses generated 48 CARD genes from 13 bacterial species in each of the populations. Spectinomycin resistance genes were the most frequently found, with an average of 65.98% in all the populations. These findings add to the knowledge on the diversity of the African D. citri populations and the probable introduction source of the psyllid in these African countries.

RevDate: 2020-06-26

Aydın MF, Altay K, Aytmirzakizi A, et al (2020)

First Molecular Detection of Dirofilaria immitis and D. repens in Dogs from Kyrgyzstan.

Acta parasitologica pii:10.1007/s11686-020-00245-8 [Epub ahead of print].

BACKGROUND: Dirofilaria immitis and Dirofilaria repens are the causative agents of cardiopulmonary and subcutaneous dirofilariosis, respectively. This neglected disease mainly seen in dogs, cats and wild carnivores is re-emerging recent years. No study was conducted on dirofilariosis in dogs in Kyrgyzstan.

PURPOSE: The goal of this study was to investigate Dirofilaria species using PCR and sequencing in dogs from Kyrgyzstan.

METHOD: Dirofilaria spp. infection in dogs was screened via convential PCR and sequencing in 337 dogs from Kyrgyzstan.

RESULT: The overall prevalence of Dirofilaria spp. was 0.59% (2/337): DNA of D. immitis was detected in one sample and DNA of D. repens in second positive sample. In second sample, parallel co-infection of D. repens with Wolbachia was also found. While D. immitis sequence showed 98.70-100% similarity with previously reported sequences of D. immitis from dog blood, D. repens shared 100% identity with other sequences of D. repens.

CONCLUSION: These results provided first evidence for Dirofilaria spp. in Kyrgyzstan and emphasized the veterinary and medical importance.

RevDate: 2020-06-25

Mateos M, Martinez Montoya H, Lanzavecchia SB, et al (2020)

Wolbachia pipientis Associated With Tephritid Fruit Fly Pests: From Basic Research to Applications.

Frontiers in microbiology, 11:1080.

Members of the true fruit flies (family Tephritidae) are among the most serious agricultural pests worldwide, whose control and management demands large and costly international efforts. The need for cost-effective and environmentally friendly integrated pest management (IPM) has led to the development and implementation of autocidal control strategies. These approaches include the widely used sterile insect technique and the incompatible insect technique (IIT). IIT relies on maternally transmitted bacteria (namely Wolbachia) to cause a conditional sterility in crosses between released mass-reared Wolbachia-infected males and wild females, which are either uninfected or infected with a different Wolbachia strain (i.e., cytoplasmic incompatibility; CI). Herein, we review the current state of knowledge on Wolbachia-tephritid interactions including infection prevalence in wild populations, phenotypic consequences, and their impact on life history traits. Numerous pest tephritid species are reported to harbor Wolbachia infections, with a subset exhibiting high prevalence. The phenotypic effects of Wolbachia have been assessed in very few tephritid species, due in part to the difficulty of manipulating Wolbachia infection (removal or transinfection). Based on recent methodological advances (high-throughput DNA sequencing) and breakthroughs concerning the mechanistic basis of CI, we suggest research avenues that could accelerate generation of necessary knowledge for the potential use of Wolbachia-based IIT in area-wide integrated pest management (AW-IPM) strategies for the population control of tephritid pests.

RevDate: 2020-06-25

Khadka S, Proshad R, Thapa A, et al (2020)

Wolbachia: a possible weapon for controlling dengue in Nepal.

Tropical medicine and health, 48:50 pii:237.

Dengue, a mosquito-borne viral infectious disease, causes a high morbidity and mortality in tropical and subtropical areas of the world. In Nepal, the first case of dengue was reported in 2004 followed by frequent outbreaks in subsequent years, with the largest being in 2019 taking the death toll of six. It is reported that the number of dengue fever cases are soaring in Nepal spreading from the plains to more hilly regions. This might have serious public health implications in the future when combined with other factors, such as: global warming, lack of early detection and treatment of dengue, lack of diagnostic facilities, poor healthcare systems and mosquito control strategies. Nepal, thus, needs a cost-effective mosquito control strategy for the prevention and control of dengue. The Wolbachia-mediated biological method of the dengue control strategy is novel, economic, and environment-friendly. It has been successfully trialed in several areas of dengue-prone countries of the world, including Australia, Malaysia, Vietnam etc. resulting in significant reductions in dengue incidence. Given the lack of effective vector control strategy and weak economic condition of the country along with the persistence of climate and environment conditions that favors the host (Aedes mosquito) for Wolbachia, this approach can be a promising option to control dengue in Nepal.

RevDate: 2020-06-23

Lucek K, Butlin R, T Patsiou (2020)

Narrow phenotypic and parasitic clines shape secondary contact zones of closely-related Erebia butterflies.

Journal of evolutionary biology [Epub ahead of print].

Zones of secondary contact between closely related taxa are a common legacy of the Quaternary ice ages. Despite their abundance, the factors that keep species apart and prevent hybridisation are often unknown. Here we study a very narrow contact zone between three closely related butterfly species of the Erebia tyndarus species complex. Using genomic data, we first determined if gene flow occurs and then assessed whether it might be hampered by differences in chromosome number between some species. We found interspecific gene flow between sibling species that differ in karyotype by one chromosome. Conversely, only F1 hybrids occurred between two species that have the same karyotype, forming a steep genomic cline. In a second step, we fitted clines to phenotypic, ecological and parasitic data to identify the factors associated with the genetic cline. We found clines for phenotypic data and the prevalence of the endosymbiont parasite Wolbachia to overlap with the genetic cline, suggesting that they might be drivers for separating the two species. Overall our results highlight that some gene flow is possible between closely-related species despite different chromosome numbers, but that other barriers restrict such gene flow.

RevDate: 2020-06-23

Wang X, Kelkar YD, Xiong X, et al (2020)

Genome Report: Whole Genome Sequence and Annotation of the Parasitoid Jewel Wasp Nasonia giraulti Laboratory Strain RV2X[υ].

G3 (Bethesda, Md.) pii:g3.120.401200 [Epub ahead of print].

Jewel wasps in the genus of Nasonia are parasitoids with haplodiploidy sex determination, rapid development and are easy to culture in the laboratory. They are excellent models for insect genetics, genomics, epigenetics, development, and evolution. Nasonia vitripennis (Nv) and N. giraulti (Ng) are closely-related species that can be intercrossed, particularly after removal of the intracellular bacterium Wolbachia, which serve as a powerful tool to map and positionally clone morphological, behavioral, expression and methylation phenotypes. The Nv reference genome was assembled using Sanger, PacBio and Nanopore approaches and annotated with extensive RNA-seq data. In contrast, Ng genome is only available through low coverage resequencing. Therefore, de novoNg assembly is in urgent need to advance this system. In this study, we report a high-quality Ng assembly using 10X Genomics linked-reads with 670X sequencing depth. The current assembly has a genome size of 259,040,977 bp in 3,160 scaffolds with 38.05% G-C and a 98.6% BUSCO completeness score. 97% of the RNA reads are perfectly aligned to the genome, indicating high quality in contiguity and completeness. A total of 14,777 genes are annotated in the Ng genome, and 72% of the annotated genes have a one-to-one ortholog in the Nv genome. We reported 5 million Ng-Nv SNPs which will facility mapping and population genomic studies in Nasonia In addition, 42 Ng-specific genes were identified by comparing with Nv genome and annotation. This is the first de novo assembly for this important species in the Nasonia model system, providing a useful new genomic toolkit.

RevDate: 2020-06-23

Laidoudi Y, Davoust B, Varloud M, et al (2020)

Development of a multiplex qPCR-based approach for the diagnosis of Dirofilaria immitis, D. repens and Acanthocheilonema reconditum.

Parasites & vectors, 13(1):319 pii:10.1186/s13071-020-04185-0.

BACKGROUND: Dirofilaria immitis, D. repens and Acanthocheilonema reconditum are the main causative agents of zoonotic canine filariosis.

METHODS: We developed a combined multiplex approach for filaria and Wolbachia detection using the 28S-based pan-filarial and 16S-based pan-Wolbachia qPCRs, respectively, involving a fast typing method of positive samples using triplex qPCR targeting A. reconditum, D. immitis and D. repens, and a duplex qPCR targeting Wolbachia of D. immitis and D. repens. The approach was complemented by a duplex qPCR for the differential diagnosis of heartworms (D. immitis and Angiostrongylus vasorum) and pan-filarial cox1 and pan-Wolbachia ftsZ PCRs to identify other filarial parasites and their Wolbachia, respectively. A total of 168 canine blood and sera samples were used to validate the approach. Spearman's correlation was used to assess the association between filarial species and the strain of Wolbachia. Positive samples for both the heartworm antigen-test after heating sera and at least one DNA-positive for D. immitis and its Wolbachia were considered true positive for heartworm infection. Indeed, the presence of D. repens DNA or that of its Wolbachia as well as A. reconditum DNA indicates true positive infections.

RESULTS: The detection limit for Wolbachia and filariae qPCRs ranged from 5 × 10-1 to 1.5 × 10-4 mf/ml of blood. When tested on clinical samples, 29.2% (49/168) tested positive for filariae or Wolbachia DNA. Filarial species and Wolbachia genotypes were identified by the combined multiplex approach from all positive samples. Each species of Dirofilaria was significantly associated with a specific genotype of Wolbachia. Compared to the true positives, the approach showed excellent agreement (k = 0.98-1). Unlike D. immitis DNA, no A. vasorum DNA was detected by the duplex qPCR. The immunochromatographic test for heartworm antigen showed a substantial (k = 0.6) and a weak (k = 0.15) agreements before and after thermal pre-treatment of sera, respectively.

CONCLUSIONS: The proposed approach is a reliable tool for the exploration and diagnosis of occult and non-occult canine filariosis. The current diagnosis of heartworm disease based on antigen detection should always be confirmed by qPCR essays. Sera heat pre-treatment is not effective and strongly discouraged.

RevDate: 2020-06-20

Driscoll TP, Verhoeve VI, Gillespie JJ, et al (2020)

A chromosome-level assembly of the cat flea genome uncovers rampant gene duplication and genome size plasticity.

BMC biology, 18(1):70 pii:10.1186/s12915-020-00802-7.

BACKGROUND: Fleas (Insecta: Siphonaptera) are small flightless parasites of birds and mammals; their blood-feeding can transmit many serious pathogens (i.e., the etiological agents of bubonic plague, endemic and murine typhus). The lack of flea genome assemblies has hindered research, especially comparisons to other disease vectors. Accordingly, we sequenced the genome of the cat flea, Ctenocephalides felis, an insect with substantial human health and veterinary importance across the globe.

RESULTS: By combining Illumina and PacBio sequencing of DNA derived from multiple inbred female fleas with Hi-C scaffolding techniques, we generated a chromosome-level genome assembly for C. felis. Unexpectedly, our assembly revealed extensive gene duplication across the entire genome, exemplified by ~ 38% of protein-coding genes with two or more copies and over 4000 tRNA genes. A broad range of genome size determinations (433-551 Mb) for individual fleas sampled across different populations supports the widespread presence of fluctuating copy number variation (CNV) in C. felis. Similarly, broad genome sizes were also calculated for individuals of Xenopsylla cheopis (Oriental rat flea), indicating that this remarkable "genome-in-flux" phenomenon could be a siphonapteran-wide trait. Finally, from the C. felis sequence reads, we also generated closed genomes for two novel strains of Wolbachia, one parasitic and one symbiotic, found to co-infect individual fleas.

CONCLUSION: Rampant CNV in C. felis has dire implications for gene-targeting pest control measures and stands to complicate standard normalization procedures utilized in comparative transcriptomics analysis. Coupled with co-infection by novel Wolbachia endosymbionts-potential tools for blocking pathogen transmission-these oddities highlight a unique and underappreciated disease vector.

RevDate: 2020-06-19

Wangkeeree J, Tewaruxsa P, Roddee J, et al (2020)

Wolbachia (Rickettsiales: Alphaproteobacteria) Infection in the Leafhopper Vector of Sugarcane White Leaf Disease.

Journal of insect science (Online), 20(3):.

Wolbachia is a maternally inherited bacterium ubiquitous in insects that has attracted interest as a prospective insect pest-control agent. Here, we detected and characterized Wolbachia in the leafhoppers Matsumuratettix hiroglyphicus (Matsumura) (Cicadellidae: Hemiptera) and Yamatotettix flavovittatus Matsumura (Cicadellidae: Hemiptera), insect vectors of the phytoplasma that cause white leaf disease in sugarcane. The 16S rRNA and wsp gene markers revealed that Wolbachia was not present in the M. hiroglyphicus but naturally occurs in Y. flavovittatus. Additionally, the infection rates in adult leafhoppers ranged from 0 to 100% depending on geographic location. Moreover, Wolbachia was detected in the eggs and first- to fifth-instar nymphs of Y. flavovittatus. A phylogenic tree of Wolbachia indicated that it resided in the monophyletic supergroup B clade and clustered in the Ori subgroup. Furthermore, fluorescence in situ hybridization revealed that Wolbachia localized to the egg apices, randomly distributed in the egg cytoplasm, and was concentrated in the nymph and adult bacteriomes, as well as occasional detection in the thorax and abdomen. To the best of our knowledge, the present study is the first to demonstrate the prevalence of Wolbachia in the leafhopper Y. flavovittatus. The obtained results would provide useful information for the future development of Wolbachia as a biological control agent for the leafhopper vectors.

RevDate: 2020-06-19

Bhattacharya T, Newton ILG, RW Hardy (2020)

Viral RNA is a target for Wolbachia-mediated pathogen blocking.

PLoS pathogens, 16(6):e1008513 pii:PPATHOGENS-D-20-00601 [Epub ahead of print].

The ability of the endosymbiont Wolbachia pipientis to restrict RNA viruses is presently being leveraged to curb global transmission of arbovirus-induced diseases. Past studies have shown that virus replication is limited early in arthropod cells colonized by the bacterium, although it is unclear if this phenomenon is replicated in mosquito cells that first encounter viruses obtained through a vertebrate blood meal. Furthermore, these cellular events neither explain how Wolbachia limits dissemination of viruses between mosquito tissues, nor how it prevents transmission of infectious viruses from mosquitoes to vertebrate host. In this study, we try to address these issues using an array of mosquito cell culture models, with an additional goal being to identify a common viral target for pathogen blocking. Our results establish the viral RNA as a cellular target for Wolbachia-mediated inhibition, with the incoming viral RNA experiencing rapid turnover following internalization in cells. This early block in replication in mosquito cells initially infected by the virus thus consequently reduces the production of progeny viruses from these same cells. However, this is not the only contributor to pathogen blocking. We show that the presence of Wolbachia reduces the per-particle infectivity of progeny viruses on naïve mosquito and vertebrate cells, consequently limiting virus dissemination and transmission, respectively. Importantly, we demonstrate that this aspect of pathogen blocking is independent of any particular Wolbachia-host association and affects viruses belonging to Togaviridae and Flaviviridae families of RNA viruses. Finally, consistent with the idea of the viral RNA as a target, we find that the encapsidated virion RNA is less infectious for viruses produced from Wolbachia-colonized cells. Collectively, our findings present a common mechanism of pathogen blocking in mosquitoes that establish a link between virus inhibition in the cell to virus dissemination and transmission.

RevDate: 2020-06-17

Hague MTJ, Mavengere H, Matute DR, et al (2020)

Environmental and Genetic Contributions to Imperfect wMel-Like Wolbachia Transmission and Frequency Variation.

Genetics pii:genetics.120.303330 [Epub ahead of print].

Maternally transmitted Wolbachia bacteria infect about half of all insect species. They usually show imperfect maternal transmission and often produce cytoplasmic incompatibility (CI). Irrespective of CI, Wolbachia frequencies tend to increase when rare only if they benefit host fitness. Several Wolbachia, including wMel that infects Drosophila melanogaster cause weak or no CI and persist at intermediate frequencies. On the island of São Tomé off West Africa, the frequencies of wMel-like Wolbachia infecting D. yakuba (wYak) and D. santomea (wSan) fluctuate, and the contributions of imperfect maternal transmission, fitness effects, and CI to these fluctuations are unknown. We demonstrate spatial variation in wYak frequency and transmission on São Tomé. Concurrent field estimates of imperfect maternal transmission do not predict spatial variation in wYak frequencies, which are highest at high altitudes where maternal transmission is the most imperfect. Genomic and genetic analyses provide little support for D. yakuba effects on wYak transmission. Instead, rearing at cool temperatures reduces wYak titer and increases imperfect transmission to levels observed on São Tomé. Using mathematical models of Wolbachia frequency dynamics and equilibria, we infer temporally variable imperfect transmission or spatially variable effects on host fitness and reproduction are required to explain wYak frequencies. In contrast, spatially stable wSan frequencies are plausibly explained by imperfect transmission, modest fitness effects, and weak CI. Our results provide insight into causes of wMel-like frequency variation in divergent hosts. Understanding this variation is crucial to explain Wolbachia spread and to improve wMel biocontrol of human disease in transinfected mosquito systems.

RevDate: 2020-06-17

Suwantika AA, Kautsar AP, Supadmi W, et al (2020)

Cost-Effectiveness of Dengue Vaccination in Indonesia: Considering Integrated Programs with Wolbachia-Infected Mosquitos and Health Education.

International journal of environmental research and public health, 17(12): pii:ijerph17124217.

Despite the fact that morbidity and mortality rates due to dengue infection in Indonesia are relatively high, a dengue vaccination has not yet been introduced. Next to vaccination, Wolbachia-infected mosquitoes and health education have been considered to be potential interventions to prevent dengue infection in Indonesia. This study was aimed to analyse the cost-effectiveness of dengue vaccination in Indonesia whilst taking Wolbachia and health education programs into account. An age-structured decision tree model was developed to assess the cost-effectiveness. Approximately 4,701,100 children were followed-up in a 10-year time horizon within a 1-year analytical cycle. We compared three vaccination strategies: one focussing on vaccination only, another combining vaccination and a Wolbachia program, and a third scenario combining vaccination and health education. All scenarios were compared with a no-intervention strategy. The result showed that only vaccination would reduce dengue fever (DF), dengue haemorrhagic fever (DHF), and dengue shock syndrome (DSS) by 123,203; 97,140 and 283 cases, respectively. It would save treatment cost at $10.3 million and $6.2 million from the healthcare and payer perspectives, respectively. The combination of vaccination and a Wolbachia program would reduce DF, DHF and DSS by 292,488; 230,541; and 672 cases, respectively. It would also save treatment cost at $24.3 million and $14.6 million from the healthcare and payer perspectives, respectively. The combination of vaccination and health education would reduce DF, DHF, and DSS by 187,986; 148,220; and 432 cases, respectively. It would save treatment cost at $15.6 million and $9.4 million from the healthcare and payer perspectives, respectively. The incremental cost-effectiveness ratios (ICERs) from the healthcare perspective were estimated to be $9,995, $4,460, and $6,399 per quality-adjusted life year (QALY) gained for the respective scenarios. ICERs from the payer perspective were slightly higher. It can be concluded that vaccination combined with a Wolbachia program was confirmed to be the most cost-effective intervention. Dengue infection rate, vaccine efficacy, cost of Wolbachia program, underreporting factor for hospitalization, vaccine price and mortality rate were considered to be the most influential parameters affecting the ICERs.

RevDate: 2020-06-12

Staunton KM, Crawford JE, Cornel D, et al (2020)

Environmental influences on Aedes aegypti catches in Biogents Sentinel traps during a Californian "rear and release" program: Implications for designing surveillance programs.

PLoS neglected tropical diseases, 14(6):e0008367 pii:PNTD-D-20-00109 [Epub ahead of print].

As Aedes aegypti continues to expand its global distribution, the diseases it vectors (dengue, Zika, chikungunya and yellow fever) are of increasing concern. Modern efforts to control this species include "rear and release" strategies where lab-reared mosquitoes are distributed throughout the landscape to replace or suppress invasive populations. These programs require intensive surveillance efforts to monitor their success, and the Biogents Sentinel (BGS) trap is one of the most effective tools for sampling adult Ae. aegypti. BGS trap catches can be highly variable throughout landscapes, so we investigated the potential impacts of environmental factors on adult Ae. aegypti capture rates during a "rear and release" program in California to better understand the relative contributions of true variability in population density across a landscape and trap context. We recorded male and female Ae. aegypti catches from BGS traps, with and without CO2, throughout control sites where no mosquitoes were released and in treatment sites where males infected with Wolbachia were released. BGS trap catches were positively influenced by higher proportions of shade or bushes in the front yard of the premises as well as the presence of potential larval habitats such as subterranean vaults. In contrast, an increase in residential habitat within a 100 m radius of trap locations negatively influenced BGS trap catches. For male Ae. aegypti, increased visual complexity of the trap location positively influenced capture rates, and the presence of yard drains negatively affected catch rates in control sites. Lastly, for BGS traps using CO2, higher catch rates were noted from traps placed greater than one meter from walls or fences for both male and female mosquitoes. These results have important implications for surveillance programs of Ae. aegypti throughout the Californian urban environment including adult monitoring during "rear and release" programs.

RevDate: 2020-06-12

Pina T, Sabater-Muñoz B, Cabedo-López M, et al (2020)

Molecular characterization of Cardinium, Rickettsia, Spiroplasma and Wolbachia in mite species from citrus orchards.

Experimental & applied acarology pii:10.1007/s10493-020-00508-z [Epub ahead of print].

Tetranychidae spider mites are considered key citrus pests in some production areas, especially Tetranychus urticae Koch. Over the past decades, pesticide overuse seems to have promoted T. urticae population selection in citrus orchards. However, the microbiota has also been pointed out as a plausible explanation for population structure or plant host specialisation observed in several arthropod species. In this work, we have determined the incidence of Cardinium, Rickettsia, Spiroplasma and Wolbachia as representatives of major distorter bacteria genera in Aplonobia histricina (Berlese), Eutetranychus banksi (McGregor), Eutetranychus orientalis (Klein), Panonychus citri (McGregor), Tetranychus evansi Baker and Pritchard, Tetranychus turkestani Ugarov and Nikolskii, and T. urticae populations from Spanish citrus orchards. Only Wolbachia was detected by PCR. The multilocus alignment approach and phylogenetic inference indicated that all detected Wolbachia belong to supergroup B. The deep analysis of each 16S rDNA, ftsZ and wsp gene sequences allowed identifying several phylogenetically different Wolbachia sequences. It probably indicates the presence of several different races or strains, all of them belonging to supergroup B. The wsp sequence typing analysis unveiled the presence of the two already identified alleles (61 and 370) and allowed to contribute with five new alleles, supporting the presence of different but related B-races in the studied mite populations. The results are discussed and related to T. urticae population structure, previously observed in Spanish citrus orchards.

RevDate: 2020-06-11

Madhav M, Brown G, Morgan JAT, et al (2020)

Transinfection of buffalo flies (Haematobia irritans exigua) with Wolbachia and effect on host biology.

Parasites & vectors, 13(1):296 pii:10.1186/s13071-020-04161-8.

BACKGROUND: Buffalo flies (Haematobia irritans exigua) (BF) and closely related horn flies (Haematobia irritans irritans) (HF) are invasive haematophagous parasites with significant economic and welfare impacts on cattle production. Wolbachia are intracellular bacteria found widely in insects and currently of much interest for use in novel strategies for the area wide control of insect pests and insect-vectored diseases. In this paper, we report the transinfection of BF towards the development of area-wide controls.

METHODS: Three stages of BF; embryos, pupae and adult female flies, were injected with different Wolbachia strains (wAlbB, wMel and wMelPop). The success of transinfection and infection dynamics was compared by real-time PCR and FISH and fitness effects were assessed in transinfected flies.

RESULTS: BF eggs were not easily injected because of their tough outer chorion and embryos were frequently damaged with less than 1% hatch rate of microinjected eggs. No Wolbachia infection was recorded in flies successfully reared from injected eggs. Adult and pupal injection resulted in higher survival rates and somatic and germinal tissue infections, with transmission to the succeeding generations on some occasions. Investigations of infection dynamics in flies from injected pupae confirmed that Wolbachia were actively multiplying in somatic tissues. Ovarian infections were confirmed with wMel and wMelPop in a number of instances, though not with wAlbB. Measurement of fitness traits indicated reduced longevity, decreased and delayed adult emergence, and reduced fecundity in Wolbachia-infected flies compared to mock-injected flies. Effects varied with the Wolbachia strain injected with most marked changes seen in the wMelPop-injected flies and least severe effects seen with wAlbB.

CONCLUSIONS: Adult and pupal injection were the most suitable methods for transinfecting BF and all three strains of Wolbachia successfully replicated in somatic tissues. The Wolbachia-induced fitness effects seen in transinfected BF suggest potential for use of the wMel or wMelPop strains in Wolbachia-based biocontrol programmes for BF.

RevDate: 2020-06-10

Cai T, Zhang Y, Liu Y, et al (2020)

Wolbachia enhances expression of NlCYP4CE1 in Nilaparvata lugens in response to imidacloprid stress.

Insect science [Epub ahead of print].

The brown planthopper, Nilaparvata lugens, is one of the main insect pests of rice. The N. lugens gene NlCYP4CE1 encodes cytochrome P450 monooxygenase (P450), which is a key enzyme in the metabolism of the insecticide imidacloprid. Previous research has suggested that the expression of NlCYP4CE1 is induced by imidacloprid stress, but the effect of bacterial symbionts on its expression has not been determined. The results of this study show that exposure to subtoxic imidacloprid changed the structure of the bacterial symbiont community in N. lugens. Specifically, the total bacterial content increased, but the bacterial species diversity decreased significantly. Wolbachia accounted for the largest proportion of bacteria in N. lugens; its abundance significantly increased after subtoxic imidacloprid exposure. The transcript level of NlCYP4CE1 was significantly increased by imidacloprid, but this effect was significantly weakened after Wolbachia was cleared with tetracycline. This result suggests that Wolbachia enhances the expression of NlCYP4CE1 to promote the detoxification metabolic response to imidacloprid stress. Understanding the effect of bacterial symbionts on gene expression in the host provides a new perspective on interactions between insecticides and their target insect pests, and highlights that subtoxic imidacloprid exposure may raise the risk of insecticide resistance by altering the structure of bacterial symbiont communities. This article is protected by copyright. All rights reserved.

RevDate: 2020-06-10

Zueva T, Morchón R, Carretón E, et al (2020)

Angiogenesis in cardiopulmonary dirofilariosis: does the Wolbachia surface protein have a pro- or anti-angiogenic effect?.

Journal of helminthology, 94:e162 pii:S0022149X20000450.

Cardiopulmonary dirofilariosis caused by Dirofilaria immitis produces inflammation, blood vessel obstruction and hypoxia, which are required conditions for the beginning of the process of neovascularization. Since D. immitis harbours intracellular symbiotic Wolbachia bacterium, the global understanding of the angiogenic process requires the analysis of the effect of the parasite molecules, but also that of Wolbachia. Canine primary lung microvascular endothelial cells were treated with the recombinant Wolbachia surface protein (rWSP) and the expression of angiogenic factors like Vascular Endothelial Growth Factor-A (VEGF-A), sFlt, membrane Endoglin (mEndoglin) and soluble Endoglin (sEndoglin), as well as the in vitro formation of pseudocapillaries, were measured. The analyses showed a significant increase in the expression of pro-angiogenic VEGF-A and anti-angiogenic sEndoglin, together with a significant decrease in both pro-angiogenic mEndoglin and pseudocapillary formation, compared to untreated controls. Due to the complexity of the angiogenic process and its relationship with other physiological processes like inflammation and fibrinolysis, these results might suggest that rWSP participate in various mechanisms related to each other and its effects might depend either on the balance between them or on the moment of their occurrence.

RevDate: 2020-06-10

Torres-Monzón JA, Casas-Martínez M, T López-Ordóñez (2020)

Infection of Aedes mosquitoes by native Wolbachia in urban cemeteries of Southern Mexico.

Salud publica de Mexico [Epub ahead of print].

OBJECTIVE: To evaluate the prevalence of Wolbachia infections in Aedes spp. field populations from cemeteries of Southern Mexico.

MATERIALS AND METHODS: Six cemeteries were selected to be sampled in the central part of the Soconusco region, Chiapas. Aedes albopictus and Ae. aegypti mosquitoes were collected during the rainy season of 2015. Females were analyzed individually by PCR to determine the presence of Wolbachia.

RESULTS: A field overall prevalence of 38% was found; only Ae. albopictus mosquitoes were positive.

CONCLUSIONS: Local strains of Wolbachia were detected and have the potential to be applied as a biological method for vector control.

RevDate: 2020-06-07

Liu XC, Li YR, Dong B, et al (2020)

The Intruding Wolbachia Strain from the Moth Fails to Establish Itself in the Fruit Fly Due to Immune and Exclusion Reactions.

Current microbiology pii:10.1007/s00284-020-02067-3 [Epub ahead of print].

Wolbachia is capable of regulating host reproduction, and thus of great significance in preventing the spread of insect-borne diseases and controlling pest insects. The fruit fly Drosophila melanogaster is an excellent model insect for understanding Wolbachia-host interactions. Here we artificially transferred the wCcep strain from the rice moth Corcyra cephalonica into D. melanogaster by microinjection. Crossing experiments indicated that wCcep could induce a high level of CI in the phylogenetically distant host D. melanogaster and imposed no negative fitness costs on host development and fecundity. Based on quantitative analysis, the titres of wCcep and the native wMel strain were negatively correlated, and wCcep could only be transmitted in the novel host for several generations (G0 to G4) after transinfection. Transcriptome sequencing indicated that the invading wCcep strain induced a significant immune- and stress-related response from the host. An association analysis between the expression of immune genes attacin-D/edin and the titre of Wolbachia by linear regression displayed a negative correlation between them. Our study suggest that the intrusion of wCcep elicited a robust immune response from the host and incurred a competitive exclusion from the native Wolbachia strain, which resulted in the failure of its establishment in D. melanogaster.

RevDate: 2020-06-05

Carretón E, Morchón R, Falcón-Cordón Y, et al (2020)

Evaluation of different dosages of doxycycline during the adulticide treatment of heartworm (Dirofilaria immitis) in dogs.

Veterinary parasitology, 283:109141 pii:S0304-4017(20)30121-7 [Epub ahead of print].

The endosymbiont bacteria Wolbachia plays an important role in the pathogenesis and inflammatory immune response to heartworm (Dirofilaria immitis) infection in dogs. Doxycycline is used to reduce Wolbachia from all life stages of heartworm to avoid large releases of the bacteria during the death of the worms. However, the dose and duration currently recommended have been extrapolated from the treatment of other rickettsial infections. Therefore, the aim was to study the dynamics of Wolbachia IgG antibodies in heartworm-infected dogs under adulticide treatment using different dosages of doxycycline. Forty-nine heartworm-infected dogs were recruited. On day 0 (diagnosis), monthly ivermectin (6 μg/kg) was prescribed, as well as daily doxycycline for 30 days, at 10 mg/kg/12 h (n = 13), 5 mg/kg/12 h (n = 19), and 10 mg/kg/24 h (n = 17). Dogs underwent adulticide treatment and blood samples were collected on days 0, 30, 90, and 120. All dogs had antibodies against recombinant Wolbachia surface protein (rWSP), confirming the important role of the bacteria in heartworm. No significant differences were found in anti-rWSP response by presence/absence of microfilariae, or by parasite burden on day 0. In all treated groups, the anti-rWSP antibody response was not significantly different between days 0 and 30 but was significantly lower between days 0 and 120 (p < 0.05). The results of the present study suggest that the administration of a lower dose than currently recommended is sufficient to achieve a significant reduction of Wolbachia in dogs infected by D. immitis.

RevDate: 2020-06-05

Bel Mokhtar N, Maurady A, Britel MR, et al (2020)

Detection of Wolbachia Infections in Natural and Laboratory Populations of the Moroccan Hessian Fly, Mayetiola destructor (Say).

Insects, 11(6): pii:insects11060340.

Mayetiola destructor (Hessian fly) is a destructive pest of wheat in several parts of the world. Here, we investigated the presence of reproductive symbionts and the effect of the geographical location on the bacterial community associated to adult Hessian flies derived from four major wheat producing areas in Morocco. Using specific 16S rDNA PCR assay, Wolbachia infection was observed in 3% of the natural populations and 10% of the laboratory population. High throughput sequencing of V3-V4 region of the bacterial 16S rRNA gene revealed that the microbiota of adult Hessian flies was significantly influenced by their native regions. A total of 6 phyla, 10 classes and 79 genera were obtained from all the samples. Confirming the screening results, Wolbachia was identified as well in the natural Hessian flies. Phylogenetic analysis using the sequences obtained in this study indicated that there is one Wolbachia strain belonging to supergroup A. To our knowledge, this is the first report of Wolbachia in Hessian fly populations. The observed low abundance of Wolbachia most likely does not indicate induction of reproductive incompatibility. Yet, this infection may give a new insight into the use of Wolbachia for the fight against Hessian fly populations.

RevDate: 2020-06-03

Adams M, McBroome J, Maurer N, et al (2020)

One fly-one genome: chromosome-scale genome assembly of a single outbred Drosophila melanogaster.

Nucleic acids research pii:5850803 [Epub ahead of print].

A high quality genome assembly is a vital first step for the study of an organism. Recent advances in technology have made the creation of high quality chromosome scale assemblies feasible and low cost. However, the amount of input DNA needed for an assembly project can be a limiting factor for small organisms or precious samples. Here we demonstrate the feasibility of creating a chromosome scale assembly using a hybrid method for a low input sample, a single outbred Drosophila melanogaster. Our approach combines an Illumina shotgun library, Oxford nanopore long reads, and chromosome conformation capture for long range scaffolding. This single fly genome assembly has a N50 of 26 Mb, a length that encompasses entire chromosome arms, contains 95% of expected single copy orthologs, and a nearly complete assembly of this individual's Wolbachia endosymbiont. The methods described here enable the accurate and complete assembly of genomes from small, field collected organisms as well as precious clinical samples.

RevDate: 2020-06-03

Zélé F, Altıntaş M, Santos I, et al (2020)

Population-specific effect of Wolbachia on the cost of fungal infection in spider mites.

Ecology and evolution, 10(9):3868-3880 pii:ECE36015.

Many studies have revealed the ability of the endosymbiotic bacterium Wolbachia to protect its arthropod hosts against diverse pathogens. However, as Wolbachia may also increase the susceptibility of its host to infection, predicting the outcome of a particular Wolbachia-host-pathogen interaction remains elusive. Yet, understanding such interactions and their eco-evolutionary consequences is crucial for disease and pest control strategies. Moreover, how natural Wolbachia infections affect artificially introduced pathogens for biocontrol has never been studied. Tetranychus urticae spider mites are herbivorous crop pests, causing severe damage on numerous economically important crops. Due to the rapid evolution of pesticide resistance, biological control strategies using entomopathogenic fungi are being developed. However, although spider mites are infected with various Wolbachia strains worldwide, whether this endosymbiont protects them from fungi is as yet unknown. Here, we compared the survival of two populations, treated with antibiotics or naturally harboring different Wolbachia strains, after exposure to the fungal biocontrol agents Metarhizium brunneum and Beauveria bassiana. To control for potential effects of the bacterial community of spider mites, we also compared the susceptibility of two populations naturally uninfected by Wolbachia, treated with antibiotics or not. In one population, Wolbachia-infected mites had a better survival than uninfected ones in absence of fungi but not in their presence, whereas in the other population Wolbachia increased the mortality induced by B. bassiana. In one naturally Wolbachia-uninfected population, the antibiotic treatment increased the susceptibility of spider mites to M. brunneum, but it had no effect in the other treatments. These results suggest that natural Wolbachia infections may not hamper and may even improve the success of biological control using entomopathogenic fungi. However, they also draw caution on the generalization of such effects, given the complexity of within-host-pathogens interaction and the potential eco-evolutionary consequences of the use of biocontrol agents for Wolbachia-host associations.

RevDate: 2020-06-03

Detcharoen M, Arthofer W, Jiggins FM, et al (2020)

Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa.

Ecology and evolution, 10(10):4457-4470 pii:ECE36212.

Wolbachia, intracellular endosymbionts, are estimated to infect about half of all arthropod species. These bacteria manipulate their hosts in various ways for their maximum benefits. The rising global temperature may accelerate species migration, and thus, horizontal transfer of Wolbachia may occur across species previously not in contact. We transinfected and then cured the alpine fly Drosophila nigrosparsa with Wolbachia strain wMel to study its effects on this species. We found low Wolbachia titer, possibly cytoplasmic incompatibility, and an increase in locomotion of both infected larvae and adults compared with cured ones. However, no change in fecundity, no impact on heat and cold tolerance, and no change in wing morphology were observed. Although Wolbachia increased locomotor activities in this species, we conclude that D. nigrosparsa may not benefit from the infection. Still, D. nigrosparsa can serve as a host for Wolbachia because vertical transmission is possible but may not be as high as in the native host of wMel, Drosophila melanogaster.

RevDate: 2020-06-03

Khanmohammadi M, Akhlaghi L, Razmjou E, et al (2020)

Morphological Description, Phylogenetic and Molecular Analysis of Dirofilaria immitis Isolated from Dogs in the Northwest of Iran.

Iranian journal of parasitology, 15(1):57-66.

Background: Dirofilariasis is a globally distributed arthropod-borne parasitic disease of mainly canids and felids. We evaluated to extend the knowledge of morpho-molecular characteristics and outer ultrastructure of Dirofilaria immitis isolated from Northwest of Iran.

Methods: Overall, 67 filarial worms including 41 females and 26 males parasites were collected from the cardiovascular system of the 43 stray dogs in Meshkinshar, Ardebil Province, Northwest of Iran in 2017, and subjected to light and scanning electron microscopy (SEM) as well as carmine alum staining for morpho-molecular and identification. Molecular methods were used for confirmation of morphological findings by sequencing of Cyto-chrome c oxidase subunit I (cox1) gene.

Results: The partial DNA sequencing of cox1 gene of adult parasites showed considerable homology and close proximity to the previously isolated from Kerman and Meshkinshahr, Iran. The lowest genetic variation and the highest intra-species variability was found in D. immitis and Dirofilaria repens, respectively. No similarity was identified between D. immitis nucleotide sequence and Wolbachia species as its endosymbiont bacteria.

Conclusion: The SEM technique is an excellent tool for differential recognition of the parasite surface morphology and molecular techniques could differentiate and identify Dirofilaria spp.

RevDate: 2020-06-03

Semiatizki A, Weiss B, Bagim S, et al (2020)

Effects, interactions, and localization of Rickettsia and Wolbachia in the house fly parasitoid, Spalangia endius.

Microbial ecology pii:10.1007/s00248-020-01520-x [Epub ahead of print].

Many insect species harbor facultative microbial symbionts that affect their biology in diverse ways. Here, we studied the effects, interactions, and localization of two bacterial symbionts-Wolbachia and Rickettsia-in the parasitoid Spalangia endius. We crossed between four S. endius colonies-Wolbachia only (W), Rickettsia only (R), both (WR), and none (aposymbiotic, APS) (16 possible crosses) and found that Wolbachia induces incomplete cytoplasmic incompatibility (CI), both when the males are W or WR. Rickettsia did not cause reproductive manipulations and did not rescue the Wolbachia-induced CI. However, when R females were crossed with W or WR males, significantly less offspring were produced compared with that of control crosses. In non-CI crosses, the presence of Wolbachia in males caused a significant reduction in offspring numbers. Females' developmental time was significantly prolonged in the R colony, with adults starting to emerge one day later than the other colonies. Other fitness parameters did not differ significantly between the colonies. Using fluorescence in situ hybridization microscopy in females, we found that Wolbachia is localized alongside Rickettsia inside oocytes, follicle cells, and nurse cells in the ovaries. However, Rickettsia is distributed also in muscle cells all over the body, in ganglia, and even in the brain.

RevDate: 2020-06-03

Papadopoulos C, Karas PA, Vasileiadis S, et al (2020)

Host Species Determines the Composition of the Prokaryotic Microbiota in Phlebotomus Sandflies.

Pathogens (Basel, Switzerland), 9(6): pii:pathogens9060428.

Phlebotomine sandflies are vectors of the humans' and mammals' parasite Leishmania spp. Although the role of gut microbiome in the biological cycle of insects is acknowledged, we still know little about the factors modulating the composition of the gut microbiota of sandflies. We tested whether host species impose a strong structural effect on the gut microbiota of Phlebotomus spp. Sandflies were collected from the island of Leros, Greece, and classified to P.papatasi, P. neglectus, P.tobbi, and P.similis, all being negative to Leishmania spp. The prokaryotic gut microbiota was determined via 16S rRNA gene amplicon sequencing. Phlebotomus species supported distinct microbial communities (p < 0.001). P.papatasi microbiota was the most distinct over-dominated by three Spiroplasma, Wolbachia and Paenibacillus operational taxonomic units (OTUs), while another Wolbachia OTU prevailed in P. neglectus. Conversely, the microbiota of P.tobbi and P.similis was composed of several less dominant OTUs. Archaea showed low presence with the dominant OTUs belonging to methanogenic Euryarcheota, ammonia-oxidizing Thaumarcheota, and Nanoarchaeota. We provide first insights into the composition of the bacterial and archaeal community of Phlebotomus sandflies and showed that, in the absence of Leishmania, host genotype is the major modulator of Phlebotomus sandfly gut microbiota.

RevDate: 2020-06-01

Mazzucco R, Nolte V, Vijayan T, et al (2020)

Long-Term Dynamics Among Wolbachia Strains During Thermal Adaptation of Their Drosophila melanogaster Hosts.

Frontiers in genetics, 11:482.

Climate change is a major evolutionary force triggering thermal adaptation in a broad range of species. While the consequences of global warming are being studied for an increasing number of species, limited attention has been given to the evolutionary dynamics of endosymbionts in response to climate change. Here, we address this question by studying the dynamics of Wolbachia, a well-studied endosymbiont of Drosophila melanogaster. D. melanogaster populations infected with 13 different Wolbachia strains were exposed to novel hot and cold laboratory environments for up to 180 generations. The short-term dynamics suggested a temperature-related fitness difference resulting in the increase of clade V strains in the cold environment only. Our long-term analysis now uncovers that clade V dominates in all replicates after generation 60 irrespective of temperature treatment. We propose that adaptation of the Drosophila host to either temperature or Drosophila C virus (DCV) infection are the cause of the replicated, temporally non-concordant Wolbachia dynamics. Our study provides an interesting case demonstrating that even simple, well-controlled experiments can result in complex, but repeatable evolutionary dynamics, thus providing a cautionary note on too simple interpretations on the impact of climate change.

RevDate: 2020-06-01

Sharma P, Rani J, Chauhan C, et al (2020)

Altered Gut Microbiota and Immunity Defines Plasmodium vivax Survival in Anopheles stephensi.

Frontiers in immunology, 11:609.

Blood-feeding enriched gut-microbiota boosts mosquitoes' anti-Plasmodium immunity. Here, we ask how Plasmodium vivax alters gut-microbiota, anti-Plasmodial immunity, and impacts tripartite Plasmodium-mosquito-microbiota interactions in the gut lumen. We used a metagenomics and RNAseq strategy to address these questions. In naïve mosquitoes, Elizabethkingia meningitis and Pseudomonas spp. are the dominant bacteria and blood-feeding leads to a heightened detection of Elizabethkingia, Pseudomonas and Serratia 16S rRNA. A parallel RNAseq analysis of blood-fed midguts also shows the presence of Elizabethkingia-related transcripts. After, P. vivax infected blood-meal, however, we do not detect bacterial 16S rRNA until circa 36 h. Intriguingly, the transcriptional expression of a selected array of antimicrobial arsenal cecropins 1-2, defensin-1, and gambicin remained low during the first 36 h-a time frame when ookinetes/early oocysts invaded the gut. We conclude during the preinvasive phase, P. vivax outcompetes midgut-microbiota. This microbial suppression likely negates the impact of mosquito immunity which in turn may enhance the survival of P. vivax. Detection of sequences matching to mosquito-associated Wolbachia opens a new inquiry for its exploration as an agent for "paratransgenesis-based" mosquito control.

RevDate: 2020-05-30

Burki T (2020)

Wolbachia, a bacterium fighting on our side.

The Lancet. Infectious diseases, 20(6):662-663.

RevDate: 2020-05-30

Tseng SP, Hsu PW, Lee CC, et al (2020)

Evidence for Common Horizontal Transmission of Wolbachia among Ants and Ant Crickets: Kleptoparasitism Added to the List.

Microorganisms, 8(6): pii:microorganisms8060805.

While Wolbachia, an intracellular bacterial symbiont, is primarily transmitted maternally in arthropods, horizontal transmission between species has been commonly documented. We examined kleptoparasitism as a potential mechanism for Wolbachia horizontal transmission, using ant crickets and their host ants as the model system. We compared prevalence and diversity of Wolbachia across multiple ant cricket species with different degrees of host specificity/integration level. Our analyses revealed at least three cases of inter-ordinal Wolbachia transfer among ant and ant crickets, and also showed that ant cricket species with high host-integration and host-specificity tend to harbor a higher Wolbachia prevalence and diversity than other types of ant crickets. This study provides empirical evidence that distribution of Wolbachia across ant crickets is largely attributable to horizontal transmission, but also elucidates the role of intimate ecological association in successful Wolbachia horizontal transmission.

RevDate: 2020-05-27

Zhang X, Liu Q, H Zhu (2020)

Modeling and dynamics of Wolbachia-infected male releases and mating competition on mosquito control.

Journal of mathematical biology pii:10.1007/s00285-020-01509-7 [Epub ahead of print].

Despite centuries of continuous efforts, mosquito-borne diseases (MBDs) remain enormous health threat of human life worldwide. Lately, the USA government has approved an innovative technology of releasing Wolbachia-infected male mosquitoes to suppress the wild mosquito population. In this paper we first introduce a stage-structured model for natural mosquitos, then we establish a new model considering the releasing of Wolbachia-infected male mosquitoes and the mating competition between the natural male mosquitoes and infected males on the suppression of natural mosquitoes. Dynamical analysis of the two models, including the existence and local stability of the equilibria and bifurcation analysis, reveals the existence of a forward bifurcation or a backward bifurcation with multiple attractors. Moreover, globally dynamical properties are further explored by using Lyapunov function and theory of monotone operators, respectively. Our findings suggest that infected male augmentation itself cannot always guarantee the success of population eradication, but leads to three possible levels of population suppression, so we define the corresponding suppression rate and estimate the minimum release ratio for population eradication. Furthermore, we study how the release ratio of infected males and natural ones, mating competition, the rate of cytoplasmic incompatibility and the basic offspring number affect the suppression rate of natural mosquitoes. Our results show that the successful eradication relies on assessing the reproductive capacity of natural mosquitoes, a selection of suitable Wolbachia strains and an appropriate release amount of infected males. This study will be helpful for public health authorities in designing proper strategies to control vector mosquitoes and prevent the epidemics of MBDs.

RevDate: 2020-05-27

Yen PS, AB Failloux (2020)

A Review: Wolbachia-Based Population Replacement for Mosquito Control Shares Common Points with Genetically Modified Control Approaches.

Pathogens (Basel, Switzerland), 9(5): pii:pathogens9050404.

The growing expansion of mosquito vectors has made mosquito-borne arboviral diseases a global threat to public health, and the lack of licensed vaccines and treatments highlight the urgent need for efficient mosquito vector control. Compared to genetically modified control strategies, the intracellular bacterium Wolbachia, endowing a pathogen-blocking phenotype, is considered an environmentally friendly strategy to replace the target population for controlling arboviral diseases. However, the incomplete knowledge regarding the pathogen-blocking mechanism weakens the reliability of a Wolbachia-based population replacement strategy. Wolbachia infections are also vulnerable to environmental factors, temperature, and host diet, affecting their densities in mosquitoes and thus the virus-blocking phenotype. Here, we review the properties of the Wolbachia strategy as an approach to control mosquito populations in comparison with genetically modified control methods. Both strategies tend to limit arbovirus infections but increase the risk of selecting arbovirus escape mutants, rendering these strategies less reliable.

RevDate: 2020-05-27

Laidoudi Y, Marie JL, Tahir D, et al (2020)

Detection of Canine Vector-Borne Filariasis and Their Wolbachia Endosymbionts in French Guiana.

Microorganisms, 8(5): pii:microorganisms8050770.

In French Guiana, canine heartworm disease is well known, but the diversity of filarial parasites of dogs remains largely unknown. A total of 98 canine blood samples from Cayenne and Kourou were assessed by a blood wet mount preparation, heartworm antigen test and molecular exploration of filarioid and Wolbachia DNAs, followed by a multiplex species-specific qPCR's identification and a subsequent sequencing analysis. Thereafter, a phylogeny based on maximum likelihood was carried out to facilitate specific identification. Five dogs were microfilaremic. Heartworm antigens were detected in 15 (15.3%) dogs. Of these, six (6.1%) were considered as occult infections as neither microfilariae nor Dirofilaria immitis DNA were detected. The 11 (11.2%) D. immitis isolates corresponded to a low virulent strain. Six of the D. immitis isolates were positive for Wolbachia endosymbionts of D. immitis belonging to the clade C DNA. Acanthocheilonema reconditum DNA was detected in 3 (3.1%) samples. Of these latter, one was found co-infected with the Brugia sp. genotype and the DNA of the clade D of the Wolbachia endosymbiont of Brugia species. This latter was also detected in two filarioid DNA-free samples. Finally, two samples were positive for Cercopithifilaria bainae genotype, which is distinct from those identified in Europe. The present study highlights the urgent need to implement chemoprophylaxis associated with anti-Wolbachia drugs to control these potential zoonoses.

RevDate: 2020-05-26

Anders KL, Indriani C, Ahmad RA, et al (2020)

Update to the AWED (Applying Wolbachia to Eliminate Dengue) trial study protocol: a cluster randomised controlled trial in Yogyakarta, Indonesia.

Trials, 21(1):429 pii:10.1186/s13063-020-04367-2.

BACKGROUND: The AWED (Applying Wolbachia to Eliminate Dengue) trial is a parallel, two-arm, non-blinded cluster randomised controlled trial that is under way in Yogyakarta, Indonesia, with the aim of measuring the efficacy of Wolbachia-infected Aedes aegypti deployments in reducing dengue incidence in an endemic setting. Enrolment began in January 2018 and is ongoing. The original study protocol was published in April 2018. Here, we describe amendments that have been made to the study protocol since commencement of the trial.

METHODS: The key protocol amendments are (1) a revised study duration with planned end of participant enrolment in August 2020, (2) the addition of new secondary objectives (i) to estimate serotype-specific efficacy of the Wolbachia intervention and (ii) to compare Ae. aegypti abundance in intervention versus untreated clusters, (3) an additional exposure classification for the per-protocol analysis where the Wolbachia exposure index is calculated using only the cluster-level Wolbachia prevalence in the participant's cluster of residence, (4) power re-estimation using a multinomial sampling method that better accounts for randomness in sampling, and (5) the addition of two trial stopping rules to address the potential for persistently low rates of virologically confirmed dengue case enrolment and Wolbachia contamination into untreated clusters. Additional minor changes to the protocol are also described.

DISCUSSION: The findings from this study will provide the first experimental evidence for the efficacy of Wolbachia in reducing dengue incidence. Enrolment in the trial will conclude this year (2020) and results will be reported shortly thereafter.

TRIAL REGISTRATION:, identifier: NCT03055585. Registered on 14 February 2017. Last updated 22 March 2020.

RevDate: 2020-05-23

Manzano-Marín A (2020)

No evidence for Wolbachia as a nutritional co-obligate endosymbiont in the aphid Pentalonia nigronervosa.

Microbiome, 8(1):72 pii:10.1186/s40168-020-00865-2.

Obligate symbiotic associations are present in a wide variety of animals with a nutrient-restricted diet. Aphids (hemiptera: Aphididae) almost-universally host Buchnera aphidicola bacteria in specialised organs (called bacteriomes). These bacteria supply the aphid with essential nutrients lacking from their diet (i.e. essential amino acids and some B vitamins). Some aphid lineages, such as species from the Lacninae subfamily, have evolved co-obligate associations with secondary endosymbionts, deriving from a loss of biotin- and riboflavin-biosynthetic genes. In this study, I re-analyse previously published sequencing data from the banana aphid Pentalonia nigronervosa. I show that the metabolic inference results from De Clerck et al. (Microbiome 3:63, 2015) are incorrect and possibly arise from the use of inadequate methods. Additionally, I discuss how the seemingly biased interpretation of their antibiotic treatment analyses together with an incorrect genome-based metabolic inference resulted in the erroneous suggestion "that a co-obligatory symbiosis between B. aphidicola and Wolbachia occurs in the banana aphid".

RevDate: 2020-05-22

Górzyńska K (2020)

Effects of the Clonostachys epichloë fungal hyperparasite on the symbiotic -interaction between Botanophila spp. flies and Epichloë sp. fungus.

Journal of invertebrate pathology pii:S0022-2011(20)30102-6 [Epub ahead of print].

Botanophila spp. flies are associated with Epichloë spp. fungi in a symbiotic relationship in which the flies benefit from stromata as a food source for both adults and larvae, and the fungus benefits from the transfer of conidia by the flies, resulting in fertilization. Derogations from this pattern indicate that the Epichloë-Botanophila interaction cannot be clearly defined. The situation may be complicated by reports of new elements of the interaction, e.g., Wolbachia bacteria present in Botanophila larvae. The present study investigates the impact of Clonostachys epichloë (Speg.) Schroers, the fungal hyperparasite of Epichloë stromata, on the Botanophila-Epichloë interaction. The interaction between C. epichloë and Botanophila spp. flies associated with Epichloë typhina subsp. clarkii (J.F. White) Leuchtm. & Schardl stromata was studied in the Holcus lanatus L. grass population. C. epichloë was present on 76.5% of stromata, covering on average 44.8 ± 32.1% of its surface and influencing the final perithecial coverage to the same extent as larval feeding. C. epichloë began to appear on stromata much later than the fly eggs and did not affect the preference for Botanophila egg laying. On the other hand, C. epichloë reduced larval hatching success and increased the mortality of the larvae. Clonostachys was responsible for 76.0% of all deaths, overgrowing brood chambers, and its mycelium was present both on and within larvae in all cases. Overall, as a result of the presence of C. epichloë, the number of Botanophila fly offspring decreased by 52.7%. Of the 26 surviving larvae, 10 (38.5%) were affected by C. epichloë, and their weight was significantly lower than that of unaffected larvae. Results show that C. epichloë, a new element of the interaction between E. typhina fungus and Botanophila flies, negatively affects both fungal reproduction and the offspring success of flies. This is the first report on the entomopathogenic activity of C. epichloë against Epichloë-associated Botanophila flies.

RevDate: 2020-05-16

Ndii MZ (2020)

Modelling the Use of Vaccine and Wolbachia on Dengue Transmission Dynamics.

Tropical medicine and infectious disease, 5(2): pii:tropicalmed5020078.

The use of vaccine and Wolbachia has been proposed as strategies against dengue. Research showed that the Wolbachia intervention is highly effective in areas with low to moderate transmission levels. On the other hand, the use of vaccine is strongly effective when it is implemented on seropositive individuals and areas with high transmission levels. The question that arises is could the combination of both strategies result in higher reduction in the number of dengue cases? This paper seeks to answer the aforementioned question by the use of a mathematical model. A deterministic model in the presence of vaccine and Wolbachia has been developed and analysed. Numerical simulations were presented and public health implications were discussed. The results showed that the performance of Wolbachia in reducing the number of dengue cases is better than that of vaccination if the vaccine efficacy is low, otherwise, the use of vaccine is sufficient to reduce dengue incidence and hence the combination of Wolbachia and vaccine is not necessary.

RevDate: 2020-05-14

Nugent CM, Elliott TA, Ratnasingham S, et al (2020)

coil: an R package for cytochrome c oxidase I (COI) DNA barcode data cleaning, translation, and error evaluation.

Genome [Epub ahead of print].

Biological conclusions based on DNA barcoding and metabarcoding analyses can be strongly influenced by the methods utilized for data generation and curation, leading to varying levels of success in the separation of biological variation from experimental error. The 5' region of cytochrome c oxidase subunit I (COI-5P) is the most common barcode gene for animals, with conserved structure and function that allows for biologically informed error identification. Here, we present coil (, an R package for the pre-processing and frameshift error assessment of COI-5P animal barcode and metabarcode sequence data. The package contains functions for placement of barcodes into a common reading frame, accurate translation of sequences to amino acids, and highlighting insertion and deletion errors. The analysis of 10 000 barcode sequences of varying quality demonstrated how coil can place barcode sequences in reading frame and distinguish sequences containing indel errors from error-free sequences with greater than 97.5% accuracy. Package limitations were tested through the analysis of COI-5P sequences from the plant and fungal kingdoms as well as the analysis of potential contaminants: nuclear mitochondrial pseudogenes and Wolbachia COI-5P sequences. Results demonstrated that coil is a strong technical error identification method but is not reliable for detecting all biological contaminants.

RevDate: 2020-05-13

Zumaquero L, Simón F, Carretón E, et al (2020)

Prevalence of canine and human dirofilariosis in Puebla, Mexico.

Veterinary parasitology, 282:109098 pii:S0304-4017(20)30078-9 [Epub ahead of print].

The objective of this work was to determine the risk of exposure to Dirofilaria immitis in the stray dog population and people living in the metropolitan area of Puebla City, Mexico, using serologic methods. A total of 283 blood salmples were collected from dogs and 254 salmples from people. The canine samples were analyzed using a commercial kit to detect D. immitis antigens and the Knott test to detect microfilariae. Human samples were analyzed by ELISAs to detect antibodies against D. immitis and Wolbachia anti-WSP, as well as Western blot to identify specific bands of the parasite in the adult antigenic extract of D. immitis. Positive results were represented on a GIS map that included layers with geoenvironmental information relevant to parasite transmission in the study area. The prevalence of D. immitis in the canine stray population was 2.12 %, with positive cases found in individuals aged 1-10 years. Human seroprevalence was established at 5.11 %, with women and men similarly affected. By age, a significantly higher seroprevalence was observed in younger individuals (<18 years) than in the rest of the population. The geolocation of the results showed that positive cases were found in the environment (within 2 km) of potentially favorable areas for mosquito breeding. The importance of human influence in the creation and maintenance of favorable conditions for the transmission of canine and human dirofilariosis within an urban area is highlighted, both by the lack of environmental sanitation and by the absence of measures to limit or eliminate the canine reservoir population.

RevDate: 2020-05-11

Kaur R, Martinez J, Rota-Stabelli O, et al (2020)

Age, tissue, genotype and virus infection regulate Wolbachia levels in Drosophila.

Molecular ecology [Epub ahead of print].

The bacterial symbiont Wolbachia can protect insects against viral pathogens, and the varying levels of antiviral protection are correlated with the endosymbiont load within the insects. To understand why Wolbachia strains differ in their antiviral effects, we investigated the factors controlling Wolbachia density in five closely related strains in their natural Drosophila hosts. We found that Wolbachia density varied greatly across different tissues and between flies of different ages, and these effects depended on the host-symbiont association. Some endosymbionts maintained largely stable densities as flies aged while others increased, and these effects in turn depended on the tissue being examined. Measuring Wolbachia rRNA levels in response to viral infection, we found that viral infection itself also altered Wolbachia levels, with FHV causing substantial reductions in symbiont loads late in the infection. This effect, however, was virus-specific as DCV had little impact on Wolbachia in all of the five host systems. Since viruses have strong tissue tropisms and antiviral protection is thought to be cell-autonomous, these effects are likely to affect the virus-blocking phenomenon. However, we were unable to find any evidence of a correlation between Wolbachia and viral titers within the same tissues. We conclude that Wolbachia levels within flies are regulated in a complex host-symbiont-virus dependent manner and this trinity is likely to influence the antiviral effects of Wolbachia.

RevDate: 2020-05-10

Zhu YX, Song ZR, Song YL, et al (2020)

Double infection of Wolbachia and Spiroplasma alters induced plant defense and spider mite fecundity.

Pest management science [Epub ahead of print].

BACKGROUND: Herbivore-associated bacterial symbionts can change plant physiology and influence the herbivore's fitness. The spider mite Tetranychus truncatus is a notorious pest harboring various bacterial symbionts, however, the effect of bacterial symbionts on host plant physiology remains unclear. Here, we investigated whether infection with the endosymbionts Wolbachia and Spiroplasma altered spider mite performance on particular tomato plants and affected the plant induced defenses.

RESULTS: Wolbachia and Spiroplasma were mainly located at the gnathosoma and ovaries of spider mite hosts. Wolbachia and Spiroplasma significantly improved spider mite reproductive performance in cultivated and wild-type tomato. However, in jasmonic acid (JA) and salicylic acid (SA)-deficient plants, there were no significant differences in the reproduction between Wolbachia and Spiroplasma-infected and uninfected spider mites. The results indicated that the reproduction benefits conferred by endosymbionts may relate to plant defenses. Both Wolbachia and Spiroplasma-infected and uninfected spider mites induced similar levels of JA and SA accumulation in tomato, whereas tomato plants damaged by Wolbachia and Spiroplasma-infected spider mites showed lower the expression levels of the JA and SA-responsive genes than those damaged by uninfected spider mites. Additionally, Wolbachia and Spiroplasma-infected mites consumed much tomato amino acid compared to uninfected spider mites, which may have contributed to host fecundity.

CONCLUSIONS: Our results suggest that the reproduction benefits conferred by endosymbionts may be associated with changes in plant defense parameters and the concentrations of plant amino acids. The results highlight the importance of endosymbionts in the interactions between spider mites and their host plants. This article is protected by copyright. All rights reserved.

RevDate: 2020-05-09

Bryant KN, ILG Newton (2020)

The Intracellular Symbiont Wolbachia pipientis Enhances Recombination in a Dose-Dependent Manner.

Insects, 11(5): pii:insects11050284.

Wolbachia pipientis is an intracellular alphaproteobacterium that infects 40%-60% of insect species and is well known for host reproductive manipulations. Although Wolbachia are primarily maternally transmitted, evidence of horizontal transmission can be found in incongruent host-symbiont phylogenies and recent acquisitions of the same Wolbachia strain by distantly related species. Parasitoids and predator-prey interactions may indeed facilitate the transfer of Wolbachia between insect lineages, but it is likely that Wolbachia are acquired via introgression in many cases. Many hypotheses exist to explain Wolbachia prevalence and penetrance, such as nutritional supplementation, protection from parasites, protection from viruses, or direct reproductive parasitism. Using classical genetics, we show that Wolbachia increase recombination in infected lineages across two genomic intervals. This increase in recombination is titer-dependent as the wMelPop variant, which infects at higher load in Drosophila melanogaster, increases recombination 5% more than the wMel variant. In addition, we also show that Spiroplasma poulsonii, another bacterial intracellular symbiont of D. melanogaster, does not induce an increase in recombination. Our results suggest that Wolbachia infection specifically alters its host's recombination landscape in a dose-dependent manner.

RevDate: 2020-05-02

Sandoval-Mojica AF, Altman S, Hunter WB, et al (2020)

Peptide Conjugated Morpholinos for Management of The Huanglongbing Pathosystem.

Pest management science [Epub ahead of print].

BACKGROUND: 'Candidatus Liberibacter asiaticus' (CLas) is the causal agent of the devastating citrus disease Huanglongbing (HLB) and is transmitted by the insect vector Diaphorina citri (Hemiptera: Liviidae). A potential approach for treating CLas infection is the use of synthetic nucleic acid-like oligomers to silence bacterial gene expression. Peptide conjugated morpholinos (PPMOs) targeting essential genes in CLas and the psyllid vector's endosymbiotic bacteria, Wolbachia (wDi), were evaluated using in vitro and in vivo assays.

RESULTS: Expression of the wDi gyrA gene was significantly reduced following incubation of Wolbachia cells with PPMOs. In addition, the viability of isolated wDi cells was greatly reduced when treated with PPMOs as compared to untreated cells. Feeding D. citri adults with a complementary PPMO (CLgyrA-14) significantly reduced the expression of CLas gyrA gene by 70%. CLas relative density was significantly lower in the psyllids fed with CLgyrA-14, when compared to untreated insects. Psyllids that were treated with CLgyrA-14 were less successful in transmitting the pathogen into uninfected plants, compared to untreated insects.

CONCLUSION: The expression of essential genes in the D. citri symbiont, Wolbachia, and the HLB pathogen were suppressed in response to PPMO treatments. This study demonstrates the potential of PPMOs as a novel strategy for management of bacterial pathogens of fruit trees, such as HLB. This article is protected by copyright. All rights reserved.

RevDate: 2020-04-28

Dahmana H, O Mediannikov (2020)

Mosquito-Borne Diseases Emergence/Resurgence and How to Effectively Control It Biologically.

Pathogens (Basel, Switzerland), 9(4): pii:pathogens9040310.

Deadly pathogens and parasites are transmitted by vectors and the mosquito is considered the most threatening vector in public health, transmitting these pathogens to humans and animals. We are currently witnessing the emergence/resurgence in new regions/populations of the most important mosquito-borne diseases, such as arboviruses and malaria. This resurgence may be the consequence of numerous complex parameters, but the major cause remains the mismanagement of insecticide use and the emergence of resistance. Biological control programmes have rendered promising results but several highly effective techniques, such as genetic manipulation, remain insufficiently considered as a control mechanism. Currently, new strategies based on attractive toxic sugar baits and new agents, such as Wolbachia and Asaia, are being intensively studied for potential use as alternatives to chemicals. Research into new insecticides, Insect Growth Regulators, and repellent compounds is pressing, and the improvement of biological strategies may provide key solutions to prevent outbreaks, decrease the danger to at-risk populations, and mitigate resistance.

RevDate: 2020-04-27

Lv N, Peng J, Chen XY, et al (2020)

Antagonistic interaction between male-killing and cytoplasmic incompatibility induced by Cardinium and Wolbachia in the whitefly, Bemisia tabaci.

Insect science [Epub ahead of print].

Cardinium and Wolbachia are maternally inherited bacterial symbionts of arthropods that can manipulate host reproduction by increasing the fitness of infected females. Here, we report that Cardinium and Wolbachia coinfection induced male-killing and cytoplasmic incompatibility (CI) when they coexisted in a cryptic species of whitefly, Bemisia tabaci Asia II7. Cardinium and Wolbachia symbionts were either singly or simultaneously localized in the bacteriocytes placed in the abdomen of B. tabaci nymphs and adults. Cardinium-Wolbachia coinfection induced male-killing and resulted in a higher female sex ratio in the intraspecific amphigenetic progeny of Asia II7 ICWH and ICWL lines; interestingly, male-killing induction was enhanced with increased Cardinium titer. Moreover, single infection of Wolbachia induced partial CI in the Asia II7 IW line and resulted in reduced fecundity, higher embryonic mortality, and lower female sex ratio. The uninfected Asia II7 IU line had significantly higher fecundity, lower embryonic and nymphal mortalities, and a lower level of CI than both the Wolbachia-infected Asia II7 IW line and the Cardinium-Wolbachia-coinfected Asia II7 ICWH line. Our findings indicate that Cardinium-Wolbachia coinfection induced male-killing, which may have had antagonistic effects on Wolbachia-induced CI in the Asia II7 whiteflies. For the first time, our study revealed that B. tabaci Asia II7 reproduction is co-manipulated by Cardinium and Wolbachia endosymbionts. This article is protected by copyright. All rights reserved.

RevDate: 2020-04-24
CmpDate: 2020-04-24

Servick K (2019)

Bacteria-armed mosquitoes make dent in dengue.

Science (New York, N.Y.), 366(6469):1056.

RevDate: 2020-04-21

Yang J, Wei S, Su D, et al (2020)

Comparison of the Rhizosphere Soil Microbial Community Structure and Diversity Between Powdery Mildew-Infected and Noninfected Strawberry Plants in a Greenhouse by High-Throughput Sequencing Technology.

Current microbiology pii:10.1007/s00284-020-01948-x [Epub ahead of print].

The aim of this study was to compare the microbial community structure and diversity in powdery mildew-infected and noninfected strawberry plant rhizosphere soils in the greenhouse based on variations in the 16S rRNA gene V3-V4 and fungal ITS2 regions by Illumina amplicon sequencing. Powdery mildew infection reduced the number of operational taxonomic units (OTUs) and prokaryotic and fungal community richness/diversity indexes in the rhizosphere soils compared with those in healthy plant soils. Furthermore, 3543 prokaryotic and 581 fungal OTUs were obtained at the 97% similarity level. Proteobacteria, Actinobacteria, Bacteroidetes, Acidobacteria, and Chloroflexi were the dominant bacterial phyla; Woesearchaeota_DHVEG-6, Bathyarchaeota, and Thaumarchaeota were the dominant archaea; and Ascomycota, Basidiomycota, unclassified_fungi, and Zygomycota were the dominant fungal phyla. Their proportions differed significantly among samples. Wolbachia, Devosia, Pseudolabrys, Streptomyces, and Rhizomicrobium were the most abundant bacterial genera; their proportions differed significantly among samples. Most Pseudomonas, Streptomyces, and 'norank' group members might be potential antagonistic microorganisms of powdery mildew pathogens, and Wolbachia and Rickettsia might be pathogen-transmitting vectors. Microascus, Clitopilus, and Ciliophora were the dominant fungi, and their community structures and abundances significantly differed among samples. Microascus, Talaromyces, Zopfiella, and Cryptococcus were relatively more abundant in the powdery mildew-infected strawberry plant rhizosphere soils. Fusarium, Trichoderma, Clitopilus, and 'unclassified' group members may be potential antagonistic populations. The results suggested that powdery mildew-infected strawberry fruits and plants cannot be consumed. This report is the first study to illustrate differences in the rhizosphere soil prokaryotic and fungal communities between powdery mildew-infected and noninfected strawberry plants in a greenhouse.

RevDate: 2020-04-21

Parker ES, Newton ILG, AP Moczek (2020)

(My Microbiome) Would Walk 10,000 miles: Maintenance and Turnover of Microbial Communities in Introduced Dung Beetles.

Microbial ecology pii:10.1007/s00248-020-01514-9 [Epub ahead of print].

Host-associated microbes facilitate diverse biotic and abiotic interactions between hosts and their environments. Experimental alterations of host-associated microbial communities frequently decrease host fitness, yet much less is known about if and how host-microbiome interactions are altered by natural perturbations, such as introduction events. Here, we begin to assess this question in Onthophagus dung beetles, a species-rich and geographically widely distributed genus whose members rely on vertically transmitted microbiota to support normal development. Specifically, we investigated to what extent microbiome community membership shifts during host introduction events and the relative significance of ancestral associations and novel environmental conditions in the structuring of microbial communities of introduced host species. Our results demonstrate that both evolutionary history and local environmental forces structure the microbial communities of these animals, but that their relative importance is shaped by the specific circumstances that characterize individual introduction events. Furthermore, we identify microbial taxa such as Dysgonomonas that may constitute members of the core Onthophagus microbiome regardless of host population or species, but also Wolbachia which associates with Onthophagus beetles in a species or even population-specific manner. We discuss the implications of our results for our understanding of the evolutionary ecology of symbiosis in dung beetles and beyond.

RevDate: 2020-04-20

Lau MJ, Ross PA, Endersby-Harshman NM, et al (2020)

Impacts of Low Temperatures on Wolbachia (Rickettsiales: Rickettsiaceae)-Infected Aedes aegypti (Diptera: Culicidae).

Journal of medical entomology pii:5822606 [Epub ahead of print].

In recent decades, the occurrence and distribution of arboviral diseases transmitted by Aedes aegypti mosquitoes has increased. In a new control strategy, populations of mosquitoes infected with Wolbachia are being released to replace existing populations and suppress arboviral disease transmission. The success of this strategy can be affected by high temperature exposure, but the impact of low temperatures on Wolbachia-infected Ae. aegypti is unclear, even though low temperatures restrict the abundance and distribution of this species. In this study, we considered low temperature cycles relevant to the spring season that are close to the distribution limits of Ae. aegypti, and tested the effects of these temperature cycles on Ae. aegypti, Wolbachia strains wMel and wAlbB, and Wolbachia phage WO. Low temperatures influenced Ae. aegypti life-history traits, including pupation, adult eclosion, and fertility. The Wolbachia-infected mosquitoes, especially wAlbB, performed better than uninfected mosquitoes. Temperature shift experiments revealed that low temperature effects on life history and Wolbachia density depended on the life stage of exposure. Wolbachia density was suppressed at low temperatures but densities recovered with adult age. In wMel Wolbachia there were no low temperature effects specific to Wolbachia phage WO. The findings suggest that Wolbachia-infected Ae. aegypti are not adversely affected by low temperatures, indicating that the Wolbachia replacement strategy is suitable for areas experiencing cool temperatures seasonally.

RevDate: 2020-04-17

Tantowijoyo W, Andari B, Arguni E, et al (2020)

Stable establishment of wMel Wolbachia in Aedes aegypti populations in Yogyakarta, Indonesia.

PLoS neglected tropical diseases, 14(4):e0008157 pii:PNTD-D-19-00023 [Epub ahead of print].

The successful establishment of the wMel strain of Wolbachia for the control of arbovirus transmission by Aedes aegypti has been proposed and is being implemented in a number of countries. Here we describe the successful establishment of the wMel strain of Wolbachia in four sites in Yogyakarta, Indonesia. We demonstrate that Wolbachia can be successfully introgressed after transient releases of wMel-infected eggs or adult mosquitoes. We demonstrate that the approach is acceptable to communities and that Wolbachia maintains itself in the mosquito population once deployed. Finally, our data show that spreading rates of Wolbachia in the Indonesian setting are slow which may reflect more limited dispersal of Aedes aegypti than seen in other sites such as Cairns, Australia.

RevDate: 2020-04-16

Seifert B (2020)

The Gene and Gene Expression (GAGE) species concept - an universal approach for all eukaryotic organisms.

Systematic biology pii:5820980 [Epub ahead of print].

The Gene and Gene Expression (GAGE) species concept, a new version of the Pragmatic Species Concept of Seifert (2014), is proposed as a concept applicable to any described recent or fossil eukaryotic organism independent from its mode of reproduction or evolutionary history. In addition to presenting the concept as such, the paper also provides practical recommendations for taxonomists when delimiting species and describing taxa. The wording of the new concept contains a heading core sentence plus five attached sentences addressing essential conditions for its translation into a sound taxonomic practice: "Species are separable clusters that have passed a threshold of evolutionary divergence and are exclusively defined by nuclear DNA sequences and/or their expression products. Nuclear DNA sequences and their expression products are different character systems but have a highly correlated indicative function. Character systems with the least risk of epigenetic or ontogenetic modification have superior indicative value when conflicts between character systems of integrative studies arise. All character systems have to be described by an adequate numerics allowing cluster formation and determination of thresholds. Thresholds for each character system should be fixed by consensus among the experts under the principle of avoiding oversplitting or lumping. Clusters must not be the expression of intraspecific polymorphism." Recognizing the distortions and conflicts caused to taxonomy through barcoding or through assessment on the basis of association with other organisms, the GAGE species concept strongly downgrades the use of cytoplasmic DNA of endosymbiotic origin (mtDNA, cpDNA) or DNA of closely associated microbes (e.g. Wolbachia bacteria) for final taxonomic decision making. Recognizing the distortion of phylogenies by the high frequency of reticulate evolution, it is argued that delimiting and naming species has to be separated from constructing bifurcating phylogenetic trees.

RevDate: 2020-04-13

Flores HA, Taneja de Bruyne J, O'Donnell TB, et al (2020)

Multiple Wolbachia strains provide comparative levels of protection against dengue virus infection in Aedes aegypti.

PLoS pathogens, 16(4):e1008433 pii:PPATHOGENS-D-19-01871 [Epub ahead of print].

The insect bacterium Wolbachia pipientis is being introgressed into Aedes aegypti populations as an intervention against the transmission of medically important arboviruses. Here we compare Ae. aegypti mosquitoes infected with wMelCS or wAlbB to the widely used wMel Wolbachia strain on an Australian nuclear genetic background for their susceptibility to infection by dengue virus (DENV) genotypes spanning all four serotypes. All Wolbachia-infected mosquitoes were more resistant to intrathoracic DENV challenge than their wildtype counterparts. Blocking of DENV replication was greatest by wMelCS. Conversely, wAlbB-infected mosquitoes were more susceptible to whole body infection than wMel and wMelCS. We extended these findings via mosquito oral feeding experiments, using viremic blood from 36 acute, hospitalised dengue cases in Vietnam, additionally including wMel and wildtype mosquitoes on a Vietnamese nuclear genetic background. As above, wAlbB was less effective at blocking DENV replication in the abdomen compared to wMel and wMelCS. The transmission potential of all Wolbachia-infected mosquito lines (measured by the presence/absence of infectious DENV in mosquito saliva) after 14 days, was significantly reduced compared to their wildtype counterparts, and lowest for wMelCS and wAlbB. These data support the use of wAlbB and wMelCS strains for introgression field trials and the biocontrol of DENV transmission. Furthermore, despite observing significant differences in transmission potential between wildtype mosquitoes from Australia and Vietnam, no difference was observed between wMel-infected mosquitoes from each background suggesting that Wolbachia may override any underlying variation in DENV transmission potential.

RevDate: 2020-04-11

Patterson EI, Villinger J, Muthoni JN, et al (2020)

Exploiting insect-specific viruses as a novel strategy to control vector-borne disease.

Current opinion in insect science, 39:50-56 pii:S2214-5745(20)30027-4 [Epub ahead of print].

Novel insect-specific viruses (ISVs) are being discovered in many important vectors due to advances in sequencing technology and a growing awareness of the virome. Several in vitro and in vivo studies indicate that ISVs are capable of modulating pathogenic arboviruses. In addition, there is growing evidence that both vertical and horizonal transmission strategies maintain ISVs in vector populations. As such there is potential to exploit ISVs for stand-alone vector control strategies and deploying them in synergy with other symbiont control approaches such as Wolbachia-mediated control. However, before the applied potential can be realized, a greater understanding of their basic biology is required, including their species range, ability to be maintained and transmitted in native and non-native vector hosts, and the effect of infection on a range of pathogens.

RevDate: 2020-04-10
CmpDate: 2020-04-10

Speer KA, Luetke E, Bush E, et al (2019)

A Fly on the Cave Wall: Parasite Genetics Reveal Fine-scale Dispersal Patterns of Bats.

The Journal of parasitology, 105(4):555-566.

Dispersal influences the evolution and adaptation of organisms, but it can be difficult to detect. Host-specific parasites provide information about the dispersal of their hosts and may be valuable for examining host dispersal that does not result in gene flow or that has low signals of gene flow. We examined the population connectivity of the buffy flower bat, Erophylla sezekorni (Chiroptera: Phyllostomidae), and its associated obligate ectoparasite, Trichobius frequens (Diptera: Streblidae), across a narrow oceanic channel in The Bahamas that has previously been implicated as a barrier to dispersal in bats. Due to the horizontal transmission of T. frequens, we were able to test the hypothesis that bats are dispersing across this channel, but this dispersal does not result in gene flow, occurs rarely, or started occurring recently. We developed novel microsatellite markers for the family Streblidae in combination with previously developed markers for bats to genotype individuals from 4 islands in The Bahamas. We provide evidence for a single population of the host, E. sezekorni, but 2 populations of its bat flies, potentially indicating a recent reduction of gene flow in E. sezekorni, rare dispersal, or infrequent transportation of bat flies with their hosts. Despite high population differentiation in bat flies indicated by microsatellites, mitochondrial DNA shows no polymorphism, suggesting that bacterial reproductive parasites may be contributing to mitochondrial DNA sweeps. Parasites, including bat flies, provide independent information about their hosts and can be used to test hypotheses of host dispersal that may be difficult to assess using host genetics alone.

RevDate: 2020-04-08

Crawford JE, Clarke DW, Criswell V, et al (2020)

Efficient production of male Wolbachia-infected Aedes aegypti mosquitoes enables large-scale suppression of wild populations.

Nature biotechnology, 38(4):482-492.

The range of the mosquito Aedes aegypti continues to expand, putting more than two billion people at risk of arboviral infection. The sterile insect technique (SIT) has been used to successfully combat agricultural pests at large scale, but not mosquitoes, mainly because of challenges with consistent production and distribution of high-quality male mosquitoes. We describe automated processes to rear and release millions of competitive, sterile male Wolbachia-infected mosquitoes, and use of these males in a large-scale suppression trial in Fresno County, California. In 2018, we released 14.4 million males across three replicate neighborhoods encompassing 293 hectares. At peak mosquito season, the number of female mosquitoes was 95.5% lower (95% CI, 93.6-96.9) in release areas compared to non-release areas, with the most geographically isolated neighborhood reaching a 99% reduction. This work demonstrates the high efficacy of mosquito SIT in an area ninefold larger than in previous similar trials, supporting the potential of this approach in public health and nuisance-mosquito eradication programs.

RevDate: 2020-04-07

Singh R, TA Linksvayer (2020)

Wolbachia-infected ant colonies have increased reproductive investment and an accelerated life cycle.

The Journal of experimental biology pii:jeb.220079 [Epub ahead of print].

Wolbachia is a widespread group of maternally-transmitted endosymbiotic bacteria that often manipulates the reproductive strategy and life history of its hosts to favor its own transmission. Wolbachia mediated phenotypic effects are well characterized in solitary hosts, but effects in social hosts are unclear. The invasive pharaoh ant, Monomorium pharaonis, shows natural variation in Wolbachia infection between colonies and can be readily bred under laboratory conditions. We previously showed that Wolbachia-infected pharaoh ant colonies had more queen-biased sex ratios than uninfected colonies, which is expected to favor the spread of maternally-transmitted Wolbachia Here, we further characterize the effects of Wolbachia on the short- and longer-term reproductive and life history traits of pharaoh ant colonies. First, we characterized the reproductive differences between naturally infected and uninfected colonies at three discrete time points and found that infected colonies had higher reproductive investment (i.e. infected colonies produced more new queens), particularly when existing colony queens were three months old. Next, we compared the long-term growth and reproduction dynamics of infected and uninfected colonies across their whole life cycle. Infected colonies had increased colony-level growth and early colony reproduction, resulting in a shorter colony life cycle, when compared to uninfected colonies.

RevDate: 2020-04-03

Ross PA, Axford JK, Callahan AG, et al (2020)

Persistent deleterious effects of a deleterious Wolbachia infection.

PLoS neglected tropical diseases, 14(4):e0008204 pii:PNTD-D-19-02146 [Epub ahead of print].

Wolbachia are being used to reduce dengue transmission by Aedes aegypti mosquitoes around the world. To date releases have mostly involved Wolbachia strains with limited fitness effects but strains with larger fitness costs could be used to suppress mosquito populations. However, such infections are expected to evolve towards decreased deleterious effects. Here we investigate potential evolutionary changes in the wMelPop infection transferred from Drosophila melanogaster to Aedes aegypti more than ten years (~120 generations) ago. We show that most deleterious effects of this infection have persisted despite strong selection to ameliorate them. The wMelPop-PGYP infection is difficult to maintain in laboratory colonies, likely due to the persistent deleterious effects coupled with occasional maternal transmission leakage. Furthermore, female mosquitoes can be scored incorrectly as infected due to transmission of Wolbachia through mating. Infection loss in colonies was not associated with evolutionary changes in the nuclear background. These findings suggest that Wolbachia transinfections with deleterious effects may have stable phenotypes which could ensure their long-term effectiveness if released in natural populations to reduce population size.

RevDate: 2020-03-26

Paredes-Montero JR, Zia-Ur-Rehman M, Hameed U, et al (2020)

Genetic variability, community structure, and horizontal transfer of endosymbionts among three Asia II-Bemisia tabaci mitotypes in Pakistan.

Ecology and evolution, 10(6):2928-2943 pii:ECE36107.

Endosymbionts associated with the whitefly Bemisia tabaci cryptic species are known to contribute to host fitness and environmental adaptation. The genetic diversity and population complexity were investigated for endosymbiont communities of B. tabaci occupying different micro-environments in Pakistan. Mitotypes of B. tabaci were identified by comparative sequence analysis of the mitochondria cytochrome oxidase I (mtCOI) gene sequence. Whitefly mitotypes belonged to the Asia II-1, -5, and -7 mitotypes of the Asia II major clade. The whitefly-endosymbiont communities were characterized based on 16S ribosomal RNA operational taxonomic unit (OTU) assignments, resulting in 43 OTUs. Most of the OTUs occurred in the Asia II-1 and II-7 mitotypes (r2 = .9, p < .005), while the Asia II-5 microbiome was less complex. The microbiome OTU groups were mitotype-specific, clustering with a basis in phylogeographical distribution and the corresponding ecological niche of their whitefly host, suggesting mitotype-microbiome co-adaptation. The primary endosymbiont Portiera was represented by a single, highly homologous OTU (0%-0.67% divergence). Two of six Arsenophonus OTUs were uniquely associated with Asia II-5 and -7, and one occurred exclusively in Asia II-1, two only in Asia II-5, and one in both Asia II-1 and -7. Four other secondary endosymbionts, Cardinium, Hemipteriphilus, Rickettsia, and Wolbachia OTUs, were found at ≤29% frequencies. The most prevalent Arsenophonus OTU was found in all three Asia II mitotypes (55% frequency), whereas the same strain of Cardinium and Wolbachia was found in both Asia II-1 and -5, and a single Hemipteriphilus OTU occurred in Asia II-1 and -7. This pattern is indicative of horizontal transfer, suggestive of a proximity between mitotypes sufficient for gene flow at overlapping mitotype ecological niches.

RevDate: 2020-03-24

Guz N, Arshad M, Cagatay NS, et al (2020)

Detection of Wolbachia (Rickettsiales: Anaplasmataceae) and Candidatus Liberibacter asiaticus (Rhizobiales: Rhizobiaceae) Associated With Diaphorina citri (Hemiptera: Liviidae) Collected From Citrus reticulata (Sapindales: Rutaceae) and Alternate Host, Cordia myxa (Boraginales: Boraginaceae).

Journal of economic entomology pii:5811319 [Epub ahead of print].

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), is an important insect pest of the citrus crop worldwide. It vectors the pathogen 'Candidatus Liberibacter asiaticus' (CLas) that causes a serious disease known as citrus greening. Here, we tested the infection frequency of Wolbachia and CLas from 100 D. citri individuals collected from two host plants belonging to families Rutaceae (Citrus reticulata Blanco) and Boraginaceae (Cordia myxa L.) using molecular methods. The following trend of endosymbionts infection in adult D. citri was found; 85.4% (35/41) by Wolbachia, and 19.5% (8/41) by CLas collected from C. reticulata plants and 65.4% (17/26) by Wolbachia, and 15.4% (4/26) by CLas in case of C. myxa plant. However, 61.5% (8/13) nymphs collected from C. reticulata and 20.0% (4/20) collected from C. myxa plants were infected by Wolbachia, while no nymph was infected by CLas collected from either host plants. Findings from this work represent the first report of CLas presence in D. citri feeding on C. myxa plants. By studying the presence of CLas with other endosymbiotic bacteria, future basic and applied research to develop control strategies can be prioritized.

RevDate: 2020-03-21

Bing XL, Zhao DS, Peng CW, et al (2020)

Similarities and spatial variations of bacterial and fungal communities in field rice planthopper (Hemiptera: Delphacidae) populationsh.

Insect science [Epub ahead of print].

Rice planthoppers are notorious plant sap-feeding pests that cause serious damage. While several microbes in rice planthoppers have been broadly characterized, the abundance and diversity of bacteria and fungi in field planthoppers are largely unknown. This study investigated the bacterial and fungal community compositions of Chinese wild rice planthoppers Laodelphax striatellus and Sogatella furcifera using parallel 16S rRNA gene amplicon and internal transcribed space region sequencing. The bacteria varied significantly between the species and were partitioned significantly by sexes, tissues and host environments in each species. The majority of bacteria were affiliated with the genera Wolbachia, Cardinium, Rickettsia and Pantoea. The abundance of Wolbachia was negatively correlated with that of Cardinium in both planthopper species. Compared with bacteria, the abundance and diversity of fungi did not differ between sexes but both were enriched in the gut. The bacterial community as a whole showed no significant correlation with the fungal community. The majority of fungi were related to Sarocladium, Alternaria, Malassezia, Aspergillus and Curvularia. A phylogenetic analysis revealed that these fungi were closely related to botanic symbionts or pathogens. Our results provide novel insights into the bacteria and fungi of rice planthoppers. This article is protected by copyright. All rights reserved.

RevDate: 2020-03-19

Dionysopoulou NK, Papanastasiou SA, Kyritsis GA, et al (2020)

Effect of host fruit, temperature and Wolbachia infection on survival and development of Ceratitis capitata immature stages.

PloS one, 15(3):e0229727 pii:PONE-D-19-25021.

The Mediterranean fruit fly, Ceratitis capitata (Diptera: Tephritidae), holds an impressive record of successful invasions promoted by the growth and development of international fruit trade. Hence, survival of immatures within infested fruit that are subjected to various conditions during transportation seems to be a crucial feature that promotes invasion success. Wolbachia pipientis is a common endosymbiont of insects and other arthropods generating several biological effects on its hosts. Existing information report the influence of Wolbachia on the fitness traits of insect host species, including the Mediterranean fruit fly. However, little is known regarding effects of Wolbachia infection on immature development in different host fruits and temperatures. This study was conducted to determine the development and survival of immature stages of four different Mediterranean fruit fly populations, either infected or uninfected with Wolbachia, in two hosts (apples, bitter oranges) under three constant temperatures (15, 25 and 30°C), constant relative humidity (45-55 ± 5%), and a photoperiod of 14L:10D. Our findings demonstrate both differential response of two fruit fly lines to Wolbachia infection and differential effects of the two Wolbachia strains on the same Mediterranean fruit fly line. Larva-to-pupa and larva-to-adult survival followed similar patterns and varied a lot among the four medfly populations, the two host fruits and the different temperatures. Pupation rates and larval developmental time were higher for larvae implanted in apples compared to bitter oranges. The survival rates of wildish medflies were higher than those of the laboratory adapted ones, particularly in bitter oranges. The Wolbachia infected medflies, expressed lower survival rates and higher developmental times, especially the wCer4 infected line. High temperatures constrained immature development and were lethal for the Wolbachia infected wCer4 medfly line. Lower temperatures inferred longer developmental times to immature stages of all medfly populations tested, in both host fruits. Implications on the ecology and survival of the fly in nature are discussed.

RevDate: 2020-03-19

Fallon AM (2020)

Computational evidence for antitoxins associated with RelE/ParE, RatA, Fic, and AbiEii-family toxins in Wolbachia genomes.

Molecular genetics and genomics : MGG pii:10.1007/s00438-020-01662-0 [Epub ahead of print].

Wolbachia is an obligate intracellular Gram-negative alpha-proteobacterium that has diverse effects on reproduction of arthropod hosts, including cytoplasmic incompatibility, male killing, feminization, and parthenogenesis. Some of these effects have important potential for control of insect pests, including mosquitoes that vector pathogens of humans. In mosquitoes, and in most other arthropods, elimination of Wolbachia by antibiotic treatment has no effect on host survival and reverses the Wolbachia-associated phenotype. Elimination of Wolbachia strain wFol, which enables parthenogenetic reproduction of the Collembolan, Folsomia candida, would result in population extinction. However, F. candida adults remain viable and resume reproduction when antibiotics are removed, suggesting that wFol survives antibiotic treatment in a quiescent persister state similar to that induced by chromosomally encoded toxin-antitoxin (TA) modules in free-living bacteria. Computational approaches were used to document the presence of antitoxin genes upstream of Wolbachia RelE/ParE, Fic, and AbiEii toxin genes. Moreover, this analysis revealed that Wolbachia RatA toxin is encoded by a single copy gene associated with an ssrS noncoding RNA gene. Documentation of potentially functional TA modules expands our understanding of the metabolic capabilities of Wolbachia, and provides an explanation for variable and sometimes contradictory results of antibiotic treatments. The presence of chromosomal TA modules in Wolbachia genomes suggests that wFol, and potentially other strains of Wolbachia, can enter a quiescent persister state.

RevDate: 2020-03-18

Wu X, Lindsey ARI, Chatterjee P, et al (2020)

Distinct epigenomic and transcriptomic modifications associated with Wolbachia-mediated asexuality.

PLoS pathogens, 16(3):e1008397 pii:PPATHOGENS-D-19-02255 [Epub ahead of print].

Wolbachia are maternally transmitted intracellular bacteria that induce a range of pathogenic and fitness-altering effects on insect and nematode hosts. In parasitoid wasps of the genus Trichogramma, Wolbachia infection induces asexual production of females, thus increasing transmission of Wolbachia. It has been hypothesized that Wolbachia infection accompanies a modification of the host epigenome. However, to date, data on genome-wide epigenomic changes associated with Wolbachia are limited, and are often confounded by background genetic differences. Here, we took sexually reproducing Trichogramma free of Wolbachia and introgressed their genome into a Wolbachia-infected cytoplasm, converting them to Wolbachia-mediated asexuality. Wolbachia was then cured from replicates of these introgressed lines, allowing us to examine the genome-wide effects of wasps newly converted to asexual reproduction while controlling for genetic background. We thus identified gene expression and DNA methylation changes associated with Wolbachia-infection. We found no overlaps between differentially expressed genes and differentially methylated genes, indicating that Wolbachia-infection associated DNA methylation change does not directly modulate levels of gene expression. Furthermore, genes affected by these mechanisms exhibit distinct evolutionary histories. Genes differentially methylated due to the infection tended to be evolutionarily conserved. In contrast, differentially expressed genes were significantly more likely to be unique to the Trichogramma lineage, suggesting host-specific transcriptomic responses to infection. Nevertheless, we identified several novel aspects of Wolbachia-associated DNA methylation changes. Differentially methylated genes included those involved in oocyte development and chromosome segregation. Interestingly, Wolbachia-infection was associated with higher levels of DNA methylation. Additionally, Wolbachia infection reduced overall variability in gene expression, even after accounting for the effect of DNA methylation. We also identified specific cases where alternative exon usage was associated with DNA methylation changes with Wolbachia infection. These results begin to reveal distinct genes and molecular pathways subject to Wolbachia induced epigenetic modification and/or host responses to Wolbachia-infection.

RevDate: 2020-03-16

van den Bosch TJM, CU Welte (2020)

The Microbial Diversity of Cabbage Pest Delia radicum Across Multiple Life Stages.

Frontiers in microbiology, 11:315.

The cabbage root fly Delia radicum is a worldwide pest that causes yield losses of many common cabbage crops. The bacteria associated with D. radicum are suggested to influence the pest status of their host. In this study, we characterized insect-associated bacteria of D. radicum across multiple life stages and of their diet plant (turnip, Brassica rapa subsp. rapa) by sequencing the V3-V4 region of 16S rRNA genes using the Illumina MiSeq platform. In total, over 1.2M paired-end reads were obtained, identifying 1006 bacterial amplicon sequence variants (ASVs) in samples obtained from the eggs, larvae, pupae and adults of D. radicum, as well as turnips that were either fresh or infested with D. radicum larvae. The microbial community in D. radicum was dominated by Wolbachia, a common endosymbiont of arthropods which we found in all of the investigated insect samples, with the pupal stage having the highest relative abundance. Moderate amounts of Firmicutes were found only in adult D. radicum flies, but not in previous life stages. Actinobacteria were mostly found on the eggs and on the skin of fresh plants on which the eggs were deposited. These plants also harbored a large amount of Pseudomonas. The bacterial diversity of the healthy turnip was low, whereas the microbial community of decaying turnips that were heavily infested by D. radicum larvae and showing symptoms of advanced soft rot was characterized by a high bacterial diversity. Taken together, this work provides insights into the bacterial communities associated with the cabbage pest D. radicum and its associated disease symptoms.

RevDate: 2020-03-14

Rossitto De Marchi B, HA Smith (2020)

Bacterial Endosymbiont Diversity Among Bemisia tabaci (Hemiptera: Aleyrodidae) Populations in Florida.

Insects, 11(3): pii:insects11030179.

The sweetpotato whitefly, Bemisia tabaci (Hemiptera: Aleyrodidae), is a pest of many economically important agricultural crops and a vector of plant viruses. Bemisia tabaci harbors facultative endosymbiont species that have been implicated in pest status, including tolerance to insecticides, virus transmission efficiency and tolerance to high-temperatures. The facultative endosymbionts reported in B. tabaci include Arsenophonus, Hamiltonella, Wolbachia, Cardinium, Fritschea and Rickettsia. We collected whitefly populations from weed and crop hosts in south Florida and identified the whitefly species as well as the facultative endosymbionts present in these populations by molecular analysis. In addition, a phylogenetic analysis of whiteflies and their endosymbionts was performed. The only facultative endosymbionts found among the B. tabaci populations collected in Florida were Hamiltonella and Rickettsia. The phylogenetic analysis revealed the low genetic diversity of whiteflies and their endosymbionts. Additionally, the phylogenetic tree clustered Rickettsia from Florida in the R1 genetic group. The results will aid to understand the role of the bacterial endosymbionts in the whitefly host.

RevDate: 2020-03-13

Hu Y, Xi Z, Liu X, et al (2020)

Correction to: Identification and molecular characterization of Wolbachia strains in natural populations of Aedes albopictus in China.

Parasites & vectors, 13(1):124 pii:10.1186/s13071-020-3917-6.

Following publication of the original article [1], the corresponding author flagged that the article had published with two errors.

RevDate: 2020-03-12

Morrow JL, Schneider DI, Klasson L, et al (2020)

Parallel sequencing of Wolbachia wCer2 from donor and novel hosts reveals multiple incompatibility factors and genome stability after host transfers.

Genome biology and evolution pii:5803650 [Epub ahead of print].

The application of Wolbachia in insect pest and vector control requires the establishment of genotypically stable host associations. The cytoplasmic incompatibility (CI) inducing Wolbachia strain wCer2 naturally occurs in the cherry fruit fly Rhagoletis cerasi as co-infection with other strains and was transferred to other fruit flies by embryonic microinjections. We obtained wCer2 genome data from its native and three novel hosts, Drosophila simulans, Drosophila melanogaster and Ceratitis capitata and assessed its genome stability, characteristics and CI factor (cif) genes. De novo assembly was successful from Wolbachia cell-enriched singly infected D. simulans embryos, with minimal host and other bacterial genome traces. The low yield of Wolbachia sequence reads from total genomic extracts of one multiply infected R. cerasi pupa and one singly infected C. capitata adult limited de novo assemblies but was sufficient for comparative analyses. Across hosts wCer2 was stable in genome synteny and content. Polymorphic nucleotide sites were found in wCer2 of each host, however only one nucleotide was different between R. cerasi and C. capitata, and none between replicated D. simulans lines. The wCer2 genome is highly similar to wAu (D. simulans), wMel (D. melanogaster) and wRec (Drosophila recens). In contrast to wMel and wRec (each with one cif gene pair) and wAu (without any cif genes), wCer2 has three pairs of Type I cif genes and one Type IV cifB gene without a cifA complement. This may explain previously reported CI patterns of wCer2, including incomplete rescue of its own CI modification in three novel host species.

RevDate: 2020-03-10

Mancini MV, Herd CS, Ant TH, et al (2020)

Wolbachia strain wAu efficiently blocks arbovirus transmission in Aedes albopictus.

PLoS neglected tropical diseases, 14(3):e0007926 pii:PNTD-D-19-01910 [Epub ahead of print].

The global incidence of arboviral diseases transmitted by Aedes mosquitoes, including dengue, chikungunya, yellow fever, and Zika, has increased dramatically in recent decades. The release of Aedes aegypti carrying the maternally inherited symbiont Wolbachia as an intervention to control arboviruses is being trialled in several countries. However, these efforts are compromised in many endemic regions due to the co-localization of the secondary vector Aedes albopictus, the Asian tiger mosquito. Ae. albopictus has an expanding global distribution following incursions into a number of new territories. To date, only the wMel and wPip strains of Wolbachia have been reported to be transferred into and characterized in this vector. A Wolbachia strain naturally infecting Drosophila simulans, wAu, was selected for transfer into a Malaysian Ae. albopictus line to create a novel triple-strain infection. The newly generated line showed self-compatibility, moderate fitness cost and complete resistance to Zika and dengue infections.

RevDate: 2020-03-07

Duan DY, Liu GH, TY Cheng (2020)

Microbiome analysis of the saliva and midgut from partially or fully engorged female adult Dermacentor silvarum ticks in China.

Experimental & applied acarology pii:10.1007/s10493-020-00478-2 [Epub ahead of print].

Dermacentor silvarum is widely distributed in northern China and transmits several pathogens that cause diseases in humans and domestic animals. We analysed the comprehensive bacterial community of the saliva and midgut from partially and fully engorged female adult D. silvarum. Dermacentor silvarum samples were collected from Guyuan, China. Bacterial DNA was extracted from the saliva and midgut contents of partially or fully engorged female adult D. silvarum. Sequencing of the V3-V4 hypervariable regions of the 16S rRNA genes was performed using the IonS5TMXL platform. The bacterial diversity in saliva was higher than in the midgut. The bacterial diversity of saliva from fully engorged ticks was greater than in partially engorged tick saliva. The bacterial diversity in midguts from partially engorged ticks was greater than in fully engorged tick midguts. Proteobacteria was the most dominant bacterial phylum in all of the samples. Twenty-nine bacterial genera were detected in all of the samples. Rickettsia, Anaplasma, and Stenotrophomonas were the main genera. The symbionts Coxiella, Arsenophonus, and Wolbachia were also detected in all of the samples. Eight bacterial species were identified in all of the experimental samples. Anaplasma marginale was reported for the first time in D. silvarum.

RevDate: 2020-03-07

Epis S, Varotto-Boccazzi I, Crotti E, et al (2020)

Chimeric symbionts expressing a Wolbachia protein stimulate mosquito immunity and inhibit filarial parasite development.

Communications biology, 3(1):105 pii:10.1038/s42003-020-0835-2.

Wolbachia can reduce the capability of mosquitoes to transmit infectious diseases to humans and is currently exploited in campaigns for the control of arboviruses, like dengue and Zika. Under the assumption that Wolbachia-mediated activation of insect immunity plays a role in the reduction of mosquito vectorial capacity, we focused our attention on the Wolbachia surface protein (WSP), a potential inductor of innate immunity. We hypothesized that the heterologous expression of this protein in gut- and tissue-associated symbionts may reduce parasite transmission. We thus engineered the mosquito bacterial symbiont Asaia to express WSP (AsaiaWSP). AsaiaWSP induced activation of the host immune response in Aedes aegypti and Anopheles stephensi mosquitoes, and inhibited the development of the heartworm parasite Dirofilaria immitis in Ae. aegypti. These results consolidate previous evidence on the immune-stimulating property of WSP and make AsaiaWSP worth of further investigations as a potential tool for the control of mosquito-borne diseases.

RevDate: 2020-03-06

O'Driscoll M, Imai N, Ferguson NM, et al (2020)

Spatiotemporal variability in dengue transmission intensity in Jakarta, Indonesia.

PLoS neglected tropical diseases, 14(3):e0008102 pii:PNTD-D-19-01147 [Epub ahead of print].

BACKGROUND: Approximately 70% of the global burden of dengue disease occurs on the Asian continent, where many large urban centres provide optimal environments for sustained endemic transmission and periodic epidemic cycles. Jakarta, the capital of Indonesia, is a densely populated megacity with hyperendemic dengue transmission. Characterization of the spatiotemporal distribution of dengue transmission intensity is of key importance for optimal implementation of novel control and prevention programmes, including vaccination. In this paper we use mathematical models to provide the first detailed description of spatial and temporal variability in dengue transmission intensity in Jakarta.

We applied catalytic models in a Bayesian framework to age-stratified dengue case notification data to estimate dengue force of infection and reporting probabilities in 42 subdistricts of Jakarta. The model was fitted to yearly and average annual data covering a 10-year period between 2008 and 2017. We estimated a long-term average annual transmission intensity of 0.130 (95%CrI: 0.129-0.131) per year in Jakarta province, ranging from 0.090 (95%CrI: 0.077-0.103) to 0.164 (95%CrI: 0.153-0.174) across subdistricts. Annual average transmission intensity in Jakarta province during the 10-year period ranged from 0.012 (95%CrI: 0.011-0.013) in 2017 to 0.124 (95%CrI: 0.121-0.128) in 2016.

CONCLUSIONS/SIGNIFICANCE: While the absolute number of dengue case notifications cannot be relied upon as a measure of endemicity, the age-distribution of reported dengue cases provides valuable insights into the underlying nature of transmission. Our estimates from yearly and average annual case notification data represent the first detailed estimates of dengue transmission intensity in Jakarta's subdistricts. These will be important to consider when assessing the population-level impact and cost-effectiveness of potential control and prevention programmes in Jakarta province, such as the controlled release of Wolbachia-carrying mosquitoes and vaccination.

RevDate: 2020-03-06

Glowska E, Filutowska ZK, Dabert M, et al (2020)

Microbial composition of enigmatic bird parasites: Wolbachia and Spiroplasma are the most important bacterial associates of quill mites (Acariformes: Syringophilidae).

MicrobiologyOpen [Epub ahead of print].

BACKGROUND: The microbiome is an integral component of many animal species, potentially affecting behavior, physiology, and other biological properties. Despite this importance, bacterial communities remain vastly understudied in many groups of invertebrates, including mites. Quill mites (Acariformes: Syringophilidae) are a poorly known group of permanent bird ectoparasites that occupy quills of feathers and feed on bird subcutaneous tissue and fluids. Most of the known species have strongly female-biased sex ratio, and it was hypothesized that this is caused by endosymbiotic bacteria. Previously, Anaplasma phagocytophilum (Foggie) and a high diversity of Wolbachia strains were detected in quill mites via targeted PCR screens. Here, we use an unbiased 16S rRNA gene amplicon sequencing approach to determine other bacteria that potentially impact quill mite biology.

RESULTS: We performed 16S rRNA gene amplicon sequencing of 126 quill mite individuals from eleven species parasitizing twelve species (four families) of passeriform birds. In addition to Wolbachia, we found Spiroplasma as potential symbiont of quill mites. Consistently, high Spiroplasma titers were only found in individuals of two mite species associated with finches of the genus Carduelis, suggesting a history of horizontal transfers of Spiroplasma via the bird host. Furthermore, there was evidence for Spiroplasma negatively affecting Wolbachia titers. We found no evidence for the previously reported Anaplasma in quill mites, but detected sequences of high similarity to the potential pathogens Brucella and Bartonella at low abundances. Other amplicon sequence variants (ASVs) could be assigned to a diverse number of bacterial taxa, including several that were previously isolated from bird skin. Further, many frequently found ASVs were assigned to taxa that show a very broad distribution with no strong prior evidence for symbiotic association with animals. We interpret these findings as evidence for a scarcity of resident microbial associates (other than inherited symbionts) in quill mites.

RevDate: 2020-03-06

Bubici G, Prigigallo MI, Garganese F, et al (2020)

First Report of Aleurocanthus spiniferus on Ailanthus altissima: Profiling of the Insect Microbiome and MicroRNAs.

Insects, 11(3): pii:insects11030161.

We report the first occurrence of the orange spiny whitefly (Aleurocanthus spiniferus; OSW) on the tree of heaven (Ailanthus altissima) in Bari, Apulia region, Italy. After our first observation in 2016, the infestation recurred regularly during the following years and expanded to the neighboring trees. Since then, we have also found the insect on numerous patches of the tree of heaven and other plant species in the Bari province. Nevertheless, the tree of heaven was not particularly threatened by the insect, so that a possible contribution by OSW for the control of such an invasive plant cannot be hypothesized hitherto. This work was also aimed at profiling the microbiome of OSW feeding on A. altissima. For this purpose, we used the denaturing gradient gel electrophoresis (DGGE) and the deep sequencing of small RNAs (sRNAs). Both techniques unveiled the presence of "Candidatus Portiera" (primary endosymbiont), Wolbachia sp. and Rickettsia sp., endosymbionts already reported for other Aleyrodidae. Deep sequencing data were analyzed by four computational pipelines in order to understand the reliability of the detection of fungi, bacteria, and viruses: Kraken, Kaiju, Velvet, and VelvetOptimiser. Some contigs assembled by Velvet or VelvetOptimiser were associated with insects, but not necessarily in the Aleurocanthus genus or Aleyrodidae family, suggesting the non-specificity of sRNAs or possible traces of parasitoids in the sample (e.g., Eretmocerus sp.). Finally, deep sequencing data were used to describe the microtranscriptome of OSW: 56 canonical and at least four high-confidence novel microRNAs (miRNAs) were identified. The overall miRNA abundance in OSW was in agreement with previous works on Bemisia tabaci, and bantam-3p, miR-276a-3p, miR-317-3p, miR-750-3p, and mir-8-3p were the most represented miRNAs.

RevDate: 2020-03-05

Nikolouli K, Sassù F, Mouton L, et al (2020)

Combining sterile and incompatible insect techniques for the population suppression of Drosophila suzukii.

Journal of pest science, 93(2):647-661.

The spotted wing Drosophila, Drosophila suzukii, has recently invaded Europe and the Americas, and it is a major threat for a wide variety of commercial soft fruits both in open field and greenhouse production systems. D. suzukii infests a wide range of ripening fruits, leading to substantial yield and revenue losses. As the application of insecticides close to the harvest period poses great concerns, the development of an efficient environment-friendly control approach to fight D. suzukii is necessary. In this study, we exploited the sterile insect technique (SIT) in combination with Wolbachia symbiosis as a population suppression approach that can constitute a potential component of an area-wide integrated pest management program. We aimed to establish a combined SIT/incompatible insect technique (IIT) protocol that would require lower irradiation doses as a complementary tool for D. suzukii management. Two D. suzukii lines trans-infected with the Wolbachia wHa and wTei strains were irradiated at doses four times less than usual (e.g., 45 Gy), and the egg hatching and adult emergence were determined. Our results indicated that wHa and wTei females as well as wHa males were sterile at this low dose. The longevity, adult emergence and flight ability of adults were evaluated, and no major effect caused by irradiation was detected. Our data indicate that a SIT/IIT protocol can be a competent approach for D. suzukii management.

RevDate: 2020-03-04

Gallo-Franco JJ, N Toro-Perea (2020)

Variations in the Bacterial Communities in Anastrepha obliqua (Diptera: Tephritidae) According to the Insect Life Stage and Host Plant.

Current microbiology pii:10.1007/s00284-020-01939-y [Epub ahead of print].

Insects have established close relationships with a wide variety of microorganisms, which play a key role in insect ecology and evolution. Fruit flies in the Tephritidae family have economic importance at the global level, including species such as Anastrepha obliqua, which is an important pest in the neotropical region. Although several studies have been performed on the microbiota associated with fruit flies, there are still large gaps in our knowledge about the bacterial communities on the genus Anastrepha. During this study, we used high-throughput sequencing to characterize the bacterial communities of the polyphagous fly A. obliqua, and we evaluated the effect of the life stage (larvae and adults) and host plant (three plant species) on the structure of these communities. Our results show that the bacterial communities in A. obliqua appears to be structured according to the insect life stage and the host plant. The predominant genera belonging to the phylum Proteobacteria were Wolbachia and Enterobacter in both larvae and adults, and they displayed differences in abundance between them, with Wolbachia sp. being more abundant in larvae and Enterobacter sp. being more abundant in adults. Differences in the structures of the bacterial communities were also observed according to the host plant with higher abundance of Enterobacter and Acetobacter bacteria in mango and plum fruits. Based on our results, it can be hypothesized that the bacterial communities on A. obliqua reorganize according to the needs of these insects during their different life stages and could also play an important role in the establishment of this fly species on different host plants. This study represents the first approach to understanding microorganism-insect interactions in fruit flies in Colombia.

RevDate: 2020-03-04

Li Y, Liu X, Wang N, et al (2020)

Background-dependent Wolbachia-mediated insecticide resistance in Laodelphax striatellus.

Environmental microbiology [Epub ahead of print].

While facultative endosymbionts are now known to protect insect hosts against pathogens and parasitoids, the effects of endosymbionts on insecticide resistance are still unclear. Here we show that Wolbachia are associated with increased resistance to the commonly used insecticide, buprofezin, in the small brown planthopper (Laodelphax striatellus) in some genetic backgrounds while having no effect in other backgrounds. In three Wolbachia-infected lines from experimental buprofezin-resistant strains and one line from a buprofezin-susceptible line established from Chuxiong, Yunnan province, China, susceptibility to buprofezin increased after removal of Wolbachia. An increase in susceptibility was also evident in a Wolbachia-infected line established from a field population in Rugao, Jiangsu province. However, no increase was evident in two field populations from Nanjing and Fengxian, Jiangsu province, China. When Wolbachia was introgressed into different genetic backgrounds, followed by Wolbachia removal, the data pointed to Wolbachia effects that depend on the nuclear background as well as on the Wolbachia strain. However, there was no relationship between Wolbachia density and the component of buprofezin resistance associated with the symbiont. The results suggest that Wolbachia effects associated with chemical resistance are complex and unpredictable, but also that they can be substantial. This article is protected by copyright. All rights reserved.

RevDate: 2020-03-03

Turner JD, Marriott AE, Hong D, et al (2020)

Novel anti-Wolbachia drugs, a new approach in the treatment and prevention of veterinary filariasis?.

Veterinary parasitology, 279:109057 pii:S0304-4017(20)30037-6 [Epub ahead of print].

Filarial nematodes are tissue-dwelling parasitic worms that can cause a range of disfiguring pathologies in humans and potentially lethal infections of companion animals. The bacterial endosymbiont, Wolbachia, is present within most human and veterinary filarial pathogens, including the causative agent of heartworm disease, Dirofilaria immitis. Doxycycline-mediated drug targeting of Wolbachia leads to sterility, clearance of microfilariae and gradual death of adult filariae. This mode of action is attractive in the treatment of filariasis because it avoids severe host inflammatory adverse reactions invoked by rapid-killing anthelmintic agents. However, doxycycline needs to be taken for four weeks to exert curative activity. In this review, we discuss the evidence that Wolbachia drug targeting is efficacious in blocking filarial larval development as well as in the treatment of chronic filarial disease. We present the current portfolio of next-generation anti-Wolbachia candidates discovered through phenotypic screening of chemical libraries and validated in a range of in vitro and in vivo filarial infection models. Several novel chemotypes have been identified with selected narrow-spectrum anti-Wolbachia specificity and superior time-to-kill kinetics compared with doxycycline. We discuss the opportunities of developing these novel anti-Wolbachia agents as either cures, adjunct therapies or new preventatives for the treatment of veterinary filariasis.

RevDate: 2020-03-03

Ourry M, Lopez V, Hervé M, et al (2020)

Long lasting effects of antibiotics on bacterial communities of adult flies.

FEMS microbiology ecology pii:5775305 [Epub ahead of print].

Insect symbionts benefit their host and their study requires large spectrum antibiotic use like tetracycline to weaken or suppress symbiotic communities. While antibiotics have a negative impact on insect fitness, little is known about antibiotic effects on insect microbial communities and how long they last. We characterized the bacterial communities of adult cabbage root fly Delia radicum in a Wolbachia-free population, evaluated the effect of tetracycline treatment on these communities over several generations. Three D. radicum generations were used: the first and second generation flies either ingested tetracycline or not, while the third generation flies were untreated but differed with their parents and/or grand-parents that had or had not been treated. Fly bacterial communities were sequenced using a 16S rRNA gene. Tetracycline decreased fly bacterial diversity and induced modifications in both bacterial abundance and relative frequencies, still visible on untreated offspring which parents and/or grandparents had been treated therefore demonstrating long lasting trans-generational effects on animal microbiomes after antibiotic treatment. Flies with an antibiotic history shared bacterial genera, potentially tetracycline-resistant and heritable. Next, the transmission should be investigated by comparing several insect development stages and plant compartments to assess vertical and horizontal transmissions of D. radicum bacterial communities.

RevDate: 2020-02-29

Zhou JC, Liu QQ, Wang QR, et al (2020)

Optimal clutch size for quality control of bisexual and Wolbachia-infected thelytokous lines of Trichogramma dendrolimi Matsumura (Hymenoptera: Trichogrammatidae) mass reared on eggs of a substitutive host, Antheraea pernyi Guérin-Méneville (Lepidoptera: Saturniidae).

Pest management science [Epub ahead of print].

BACKGROUND: Trichogramma dendrolimi has been widely used in augmentative biocontrol of lepidopteran pests in China. In mass production of T. dendrolimi using Antheraea pernyi eggs as substitutive hosts, which are large in size, clutch size is a parameter of importance to produce high quality parasitoids. Here, we aimed to determine the optimal clutch size for the bisexual Wolbachia-infected line (TdB) and Wolbachia-infected thelytokous line (TdT) of T. dendrolimi reared on A. pernyi eggs.

RESULTS: A medium clutch size of 42.75-62.27 for TdB and 52.93-57.14 for TdT was optimal to maximize fitness-correlated traits of parasitoid individual. The optimal clutch sizes with maximized parameters included adult emergence rate, adult body size, adult longevity, fecudity, and sum of fecundity of all females per brood were 58.31 (86.00%), 42.75 (231.11 μm), 50.92 (2.69 d), 62.27 (150.89 eggs), and 83.25 (7926.33 eggs) for TdB and 57.14 (94.54%), 52.93 (236.97 μm), 53.64 (2.62 d), 56.80 (161.01 eggs), and 70.10 (8579.71 eggs) for TdT. The Wolbachia-infected thelytokous line had a shorter adult longevity, longer development time, and higher adult emergence rate than did its non-infected bisexual counterpart.

CONCLUSION: A medium brood size in a A. pernyi egg host was optimal to produce offspring parasitoids with higher fitness parameters for both bisexual Wolbachia-uninfected and thelytokous Wolbachia-infected lines of T. dendrolimi. The determination of optimal clutch size for T. dendrolimi will provide the reference for the quality control of T. dendrolimi production and improvement of the field performance of the wasps. This article is protected by copyright. All rights reserved.

RevDate: 2020-02-25

Kaczmarczyk-Ziemba A, Zagaja M, Wagner GK, et al (2020)

First Insight into Microbiome Profiles of Myrmecophilous Beetles and Their Host, Red Wood Ant Formica polyctena (Hymenoptera: Formicidae)-A Case Study.

Insects, 11(2): pii:insects11020134.

Formica polyctena belongs to the red wood ant species group. Its nests provide a stable, food rich, and temperature and humidity controlled environment, utilized by a wide range of species, called myrmecophiles. Here, we used the high-throughput sequencing of the 16S rRNA gene on the Illumina platform for identification of the microbiome profiles of six selected myrmecophilous beetles (Dendrophilus pygmaeus, Leptacinus formicetorum, Monotoma angusticollis, Myrmechixenus subterraneus, Ptenidium formicetorum and Thiasophila angulata) and their host F. polyctena. Analyzed bacterial communities consisted of a total of 23 phyla, among which Proteobacteria, Actinobacteria, and Firmicutes were the most abundant. Two known endosymbionts-Wolbachia and Rickettsia-were found in the analyzed microbiome profiles and Wolbachia was dominant in bacterial communities associated with F. polyctena, M. subterraneus, L. formicetorum and P. formicetorum (>90% of reads). In turn, M. angusticollis was co-infected with both Wolbachia and Rickettsia, while in the microbiome of T. angulata, the dominance of Rickettsia has been observed. The relationships among the microbiome profiles were complex, and no relative abundance pattern common to all myrmecophilous beetles tested was observed. However, some subtle, species-specific patterns have been observed for bacterial communities associated with D. pygmaeus, M. angusticollis, and T. angulata.

RevDate: 2020-02-24

Hawryluk N (2020)

Macrofilaricides: An Unmet Medical Need for Filarial Diseases.

ACS infectious diseases [Epub ahead of print].

Neglected parasitic helminth diseases, such as onchocerciasis and lymphatic filariasis, affect an estimated 145 million people worldwide, creating a serious health burden in endemic areas such as sub-Saharan Africa and India. Although these diseases are not usually lethal, infections caused by Onchocerca volvulus (onchocerciasis) and Wuchereria/Brugia (LF) cause severe debilitation and chronic disability to infected individuals. The adult worms responsible for infection can reproduce from 5 to up to 14 years, releasing millions of microfilariae, juvenile worms, over an infected individual's lifetime. The current treatments for controlling human filarial infections is focused on killing microfilariae, the earliest larval stage. Currently, there is an unmet medical need for treatments consisting of a macrofilaricidal regimen, one that targets the adult stage of the parasite, increases the rate of elimination, allows for safe use in co-endemic regions of O. volvulus and L. loa, and provides a rapid method to resolve reinfections. Herein, recent approaches for targeting human filarial diseases are discussed including direct acting agents to target parasitic nematodes and anti-bacterial approaches to target the endosymbiotic bacteria, Wolbachia. Keywords: filariasis, onchocerciasis, Wolbachia, microfilaria, macrofilaria, Loa loa.

RevDate: 2020-02-20

Zhang D, Wang Y, He K, et al (2020)

Wolbachia limits pathogen infections through induction of host innate immune responses.

PloS one, 15(2):e0226736 pii:PONE-D-19-32787.

BACKGROUND: Wolbachia has been reported to suppress a variety of pathogen infections in mosquitoes, but the mechanism is undefined. Two possibilities have been proposed. One is that Wolbachia activates host immune responses, and the other one is that Wolbachia competes with pathogens for limited nutrients.

In this study, we compared host immune responses and the densities of two different strains of Wolbachia in naturally occurring parental and artificially created hybrid host genetic backgrounds. No significant difference in Wolbachia density was found between these hosts. We found that Wolbachia could activate host innate immune responses when the host genetic profile was different from that of its natural host. When these hosts were challenged with pathogenic bacteria, mosquitoes in new host-Wolbachia symbioses had a higher survival rate than in old host-Wolbachia symbioses.

CONCLUSIONS/SIGNIFICANCE: The presence of Wolbachia per se does not necessarily affect pathogen infections, suggesting that a competition for limited nutrients is not the main reason for Wolbachia-mediated pathogen suppression. Instead, host immune responses are responsible for it. The elucidation of an immunity nature of PI is important to guide future practice: Wolbachia may be genetically engineered to be more immunogenic, it is desired to search and isolate more strains of Wolbachia, and test more host-Wolbachia symbioses for future applications. Our results also suggest Wolbachia-based PI may be applied to naturally Wolbachia-infected mosquito populations, and extend to the control of a broader range of mosquito-borne diseases.

RevDate: 2020-02-20

Ross PA, Callahan AG, Yang Q, et al (2020)

An elusive endosymbiont: Does Wolbachia occur naturally in Aedes aegypti?.

Ecology and evolution, 10(3):1581-1591 pii:ECE36012.

Wolbachia are maternally inherited endosymbiotic bacteria found within many insect species. Aedes mosquitoes experimentally infected with Wolbachia are being released into the field for Aedes-borne disease control. These Wolbachia infections induce cytoplasmic incompatibility which is used to suppress populations through incompatible matings or replace populations through the reproductive advantage provided by this mechanism. However, the presence of naturally occurring Wolbachia in target populations could interfere with both population replacement and suppression programs depending on the compatibility patterns between strains. Aedes aegypti were thought to not harbor Wolbachia naturally but several recent studies have detected Wolbachia in natural populations of this mosquito. We therefore review the evidence for natural Wolbachia infections in A. aegypti to date and discuss limitations of these studies. We draw on research from other mosquito species to outline the potential implications of natural Wolbachia infections in A. aegypti for disease control. To validate previous reports, we obtained a laboratory population of A. aegypti from New Mexico, USA, that harbors a natural Wolbachia infection, and we conducted field surveys in Kuala Lumpur, Malaysia, where a natural Wolbachia infection has also been reported. However, we were unable to detect Wolbachia in both the laboratory and field populations. Because the presence of naturally occurring Wolbachia in A. aegypti could have profound implications for Wolbachia-based disease control programs, it is important to continue to accurately assess the Wolbachia status of target Aedes populations.


ESP Quick Facts

ESP Origins

In the early 1990's, Robert Robbins was a faculty member at Johns Hopkins, where he directed the informatics core of GDB — the human gene-mapping database of the international human genome project. To share papers with colleagues around the world, he set up a small paper-sharing section on his personal web page. This small project evolved into The Electronic Scholarly Publishing Project.

ESP Support

In 1995, Robbins became the VP/IT of the Fred Hutchinson Cancer Research Center in Seattle, WA. Soon after arriving in Seattle, Robbins secured funding, through the ELSI component of the US Human Genome Project, to create the original ESP.ORG web site, with the formal goal of providing free, world-wide access to the literature of classical genetics.

ESP Rationale

Although the methods of molecular biology can seem almost magical to the uninitiated, the original techniques of classical genetics are readily appreciated by one and all: cross individuals that differ in some inherited trait, collect all of the progeny, score their attributes, and propose mechanisms to explain the patterns of inheritance observed.

ESP Goal

In reading the early works of classical genetics, one is drawn, almost inexorably, into ever more complex models, until molecular explanations begin to seem both necessary and natural. At that point, the tools for understanding genome research are at hand. Assisting readers reach this point was the original goal of The Electronic Scholarly Publishing Project.

ESP Usage

Usage of the site grew rapidly and has remained high. Faculty began to use the site for their assigned readings. Other on-line publishers, ranging from The New York Times to Nature referenced ESP materials in their own publications. Nobel laureates (e.g., Joshua Lederberg) regularly used the site and even wrote to suggest changes and improvements.

ESP Content

When the site began, no journals were making their early content available in digital format. As a result, ESP was obliged to digitize classic literature before it could be made available. For many important papers — such as Mendel's original paper or the first genetic map — ESP had to produce entirely new typeset versions of the works, if they were to be available in a high-quality format.

ESP Help

Early support from the DOE component of the Human Genome Project was critically important for getting the ESP project on a firm foundation. Since that funding ended (nearly 20 years ago), the project has been operated as a purely volunteer effort. Anyone wishing to assist in these efforts should send an email to Robbins.

ESP Plans

With the development of methods for adding typeset side notes to PDF files, the ESP project now plans to add annotated versions of some classical papers to its holdings. We also plan to add new reference and pedagogical material. We have already started providing regularly updated, comprehensive bibliographies to the ESP.ORG site.

Electronic Scholarly Publishing
961 Red Tail Lane
Bellingham, WA 98226

E-mail: RJR8222 @

Papers in Classical Genetics

The ESP began as an effort to share a handful of key papers from the early days of classical genetics. Now the collection has grown to include hundreds of papers, in full-text format.

Digital Books

Along with papers on classical genetics, ESP offers a collection of full-text digital books, including many works by Darwin (and even a collection of poetry — Chicago Poems by Carl Sandburg).


ESP now offers a much improved and expanded collection of timelines, designed to give the user choice over subject matter and dates.


Biographical information about many key scientists.

Selected Bibliographies

Bibliographies on several topics of potential interest to the ESP community are now being automatically maintained and generated on the ESP site.

ESP Picks from Around the Web (updated 07 JUL 2018 )