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Pujhari S, Hughes GL, Pakpour N, Suzuki Y, Rasgon JL. Wolbachia-induced inhibition of O'nyong nyong virus in Anopheles mosquitoes is mediated by Toll signaling and modulated by cholesterol. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.31.543096. [PMID: 37397989 PMCID: PMC10312510 DOI: 10.1101/2023.05.31.543096] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/04/2023]
Abstract
Enhanced host immunity and competition for metabolic resources are two main competing hypotheses for the mechanism of Wolbachia-mediated pathogen inhibition in arthropods. Using an Anopheles mosquito - somatic Wolbachia infection - O'nyong nyong virus (ONNV) model, we demonstrate that the mechanism underpinning Wolbachia-mediated virus inhibition is up-regulation of the Toll innate immune pathway. However, the viral inhibitory properties of Wolbachia were abolished by cholesterol supplementation. This result was due to Wolbachia-dependent cholesterol-mediated suppression of Toll signaling rather than competition for cholesterol between Wolbachia and virus. The inhibitory effect of cholesterol was specific to Wolbachia-infected Anopheles mosquitoes and cells. These data indicate that both Wolbachia and cholesterol influence Toll immune signaling in Anopheles mosquitoes in a complex manner and provide a functional link between the host immunity and metabolic competition hypotheses for explaining Wolbachia-mediated pathogen interference in mosquitoes. In addition, these results provide a mechanistic understanding of the mode of action of Wolbachia-induced pathogen blocking in Anophelines, which is critical to evaluate the long-term efficacy of control strategies for malaria and Anopheles-transmitted arboviruses.
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Affiliation(s)
- Sujit Pujhari
- The Department of Entomology, Center for Infectious Disease Dynamics, and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
| | - Grant L Hughes
- The Department of Entomology, Center for Infectious Disease Dynamics, and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
- Departments of Vector Biology and Tropical Disease Biology, Centre for Neglected Tropical Disease, Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | | | - Yasutsugu Suzuki
- The Department of Entomology, Center for Infectious Disease Dynamics, and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
- Center for Marine Environmental Studies, Ehime University, Matsuyama, Japan
| | - Jason L Rasgon
- The Department of Entomology, Center for Infectious Disease Dynamics, and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA, USA
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Mishra R, Hua G, Bagal UR, Champagne DE, Adang MJ. Anopheles gambiae strain (Ag55) cultured cells originated from Anopheles coluzzii and are phagocytic with hemocyte-like gene expression. INSECT SCIENCE 2022; 29:1346-1360. [PMID: 35358364 DOI: 10.1111/1744-7917.13036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 02/21/2022] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
Anopheles gambiae and Anopheles coluzzii are closely related species that are predominant vectors of malaria in Africa. Recently, A. gambiae form M was renamed A. coluzzii and we now conclude on the basis of a diagnostic PCR-restriction fragment length polymorphism assay that Ag55 cells were derived from A. coluzzii. We established an Ag55 cell transcriptome, and KEGG pathway analysis showed that Ag55 cells are enriched in phagosome pathway transcripts. The Ag55 transcriptome has an abundance of specific transcripts characteristic of mosquito hemocytes. Functional E. coli bioparticle uptake experiments visualized by fluorescence microscopy and confocal microscopy and quantified by flow cytometry establish the phagocytic competence of Ag55 cells. Results from this investigation of Ag55 cell properties will guide researchers in the use and engineering of the Ag55 cell line to better enable investigations of Plasmodium, other microbes, and insecticidal toxins.
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Affiliation(s)
- Ruchir Mishra
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
- Department of Entomology and Nematology, University of Florida, Gainesville, Florida, USA
| | - Gang Hua
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
| | - Ujwal R Bagal
- Institute of Bioinformatics, University of Georgia, Athens, Georgia, USA
| | - Donald E Champagne
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
| | - Michael J Adang
- Department of Entomology, College of Agricultural and Environmental Sciences, University of Georgia, Athens, Georgia, USA
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, Georgia, USA
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Arellano AA, Sommer AJ, Coon KL. Beyond canonical models: why a broader understanding of Diptera-microbiota interactions is essential for vector-borne disease control. Evol Ecol 2022; 37:165-188. [PMID: 37153630 PMCID: PMC10162596 DOI: 10.1007/s10682-022-10197-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Vector-borne diseases constitute a major global public health threat. The most significant arthropod disease vectors are predominantly comprised of members of the insect order Diptera (true flies), which have long been the focus of research into host-pathogen dynamics. Recent studies have revealed the underappreciated diversity and function of dipteran-associated gut microbial communities, with important implications for dipteran physiology, ecology, and pathogen transmission. However, the effective parameterization of these aspects into epidemiological models will require a comprehensive study of microbe-dipteran interactions across vectors and related species. Here, we synthesize recent research into microbial communities associated with major families of dipteran vectors and highlight the importance of development and expansion of experimentally tractable models across Diptera towards understanding the functional roles of the gut microbiota in modulating disease transmission. We then posit why further study of these and other dipteran insects is not only essential to a comprehensive understanding of how to integrate vector-microbiota interactions into existing epidemiological frameworks, but our understanding of the ecology and evolution of animal-microbe symbiosis more broadly.
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Affiliation(s)
- Aldo A. Arellano
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Andrew J. Sommer
- Microbiology Doctoral Training Program, University of Wisconsin-Madison, Madison, WI 53706, USA
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Kerri L. Coon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
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Neupane S, Bonilla SI, Manalo AM, Pelz-Stelinski KS. Complete de novo assembly of Wolbachia endosymbiont of Diaphorina citri Kuwayama (Hemiptera: Liviidae) using long-read genome sequencing. Sci Rep 2022; 12:125. [PMID: 34996906 PMCID: PMC8741817 DOI: 10.1038/s41598-021-03184-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 11/26/2021] [Indexed: 01/23/2023] Open
Abstract
Wolbachia, a gram-negative \documentclass[12pt]{minimal}
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\begin{document}$$\mathrm{\alpha }$$\end{document}α-proteobacterium, is an endosymbiont found in some arthropods and nematodes. Diaphorina citri Kuwayama, the vector of ‘Candidatus Liberibacter asiaticus’ (CLas), are naturally infected with a strain of Wolbachia (wDi), which has been shown to colocalize with the bacteria pathogens CLas, the pathogen associated with huanglongbing (HLB) disease of citrus. The relationship between wDi and CLas is poorly understood in part because the complete genome of wDi has not been available. Using high-quality long-read PacBio circular consensus sequences, we present the largest complete circular wDi genome among supergroup-B members. The assembled circular chromosome is 1.52 megabases with 95.7% genome completeness with contamination of 1.45%, as assessed by checkM. We identified Insertion Sequences (ISs) and prophage genes scattered throughout the genomes. The proteins were annotated using Pfam, eggNOG, and COG that assigned unique domains and functions. The wDi genome was compared with previously sequenced Wolbachia genomes using pangenome and phylogenetic analyses. The availability of a complete circular chromosome of wDi will facilitate understanding of its role within the insect vector, which may assist in developing tools for disease management. This information also provides a baseline for understanding phylogenetic relationships among Wolbachia of other insect vectors.
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Affiliation(s)
- Surendra Neupane
- Entomology and Nematology Department, Citrus Research and Education Center/IFAS, University of Florida, Lake Alfred, Florida, 33850, USA
| | - Sylvia I Bonilla
- Entomology and Nematology Department, Citrus Research and Education Center/IFAS, University of Florida, Lake Alfred, Florida, 33850, USA
| | - Andrew M Manalo
- Entomology and Nematology Department, Citrus Research and Education Center/IFAS, University of Florida, Lake Alfred, Florida, 33850, USA
| | - Kirsten S Pelz-Stelinski
- Entomology and Nematology Department, Citrus Research and Education Center/IFAS, University of Florida, Lake Alfred, Florida, 33850, USA.
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Growth and Maintenance of Wolbachia in Insect Cell Lines. INSECTS 2021; 12:insects12080706. [PMID: 34442272 PMCID: PMC8396524 DOI: 10.3390/insects12080706] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 08/02/2021] [Accepted: 08/03/2021] [Indexed: 12/02/2022]
Abstract
Simple Summary Wolbachia is an intracellular bacterium that occurs in arthropods and in filarial worms. First described nearly a century ago in the reproductive tissues of Culex pipiens mosquitoes, Wolbachia is now known to occur in roughly 50% of insect species, and has been considered the most abundant intracellular bacterium on earth. In insect hosts, Wolbachia modifies reproduction in ways that facilitate spread of the microbe within the host population, but otherwise is relatively benign. In this “gene drive” capacity, Wolbachia provides a tool for manipulating mosquito populations. In mosquitoes, Wolbachia causes cytoplasmic incompatibility, in which the fusion of egg and sperm nuclei is disrupted, and eggs fail to hatch, depending on the presence/absence of Wolbachia in the parent insects. Recent findings demonstrate that Wolbachia from infected insects can be transferred into mosquito species that do not host a natural infection. When transinfected into Aedes aegypti, an important vector of dengue and Zika viruses, Wolbachia causes cytoplasmic incompatibility and, in addition, decreases the mosquito’s ability to transmit viruses to humans. This review addresses the maintenance of Wolbachia in insect cell lines, which provide a tool for high-level production of infectious bacteria. In vitro technologies will improve use of Wolbachia for pest control, and provide the microbiological framework for genetic engineering of this promising biocontrol agent. Abstract The obligate intracellular microbe, Wolbachia pipientis (Rickettsiales; Anaplasmataceae), is a Gram-negative member of the alpha proteobacteria that infects arthropods and filarial worms. Although closely related to the genera Anaplasma and Ehrlichia, which include pathogens of humans, Wolbachia is uniquely associated with invertebrate hosts in the clade Ecdysozoa. Originally described in Culex pipiens mosquitoes, Wolbachia is currently represented by 17 supergroups and is believed to occur in half of all insect species. In mosquitoes, Wolbachia acts as a gene drive agent, with the potential to modify vector populations; in filarial worms, Wolbachia functions as a symbiont, and is a target for drug therapy. A small number of Wolbachia strains from supergroups A, B, and F have been maintained in insect cell lines, which are thought to provide a more permissive environment than the natural host. When transferred back to an insect host, Wolbachia produced in cultured cells are infectious and retain reproductive phenotypes. Here, I review applications of insect cell lines in Wolbachia research and describe conditions that facilitate Wolbachia infection and replication in naive host cells. Progress in manipulation of Wolbachia in vitro will enable genetic and biochemical advances that will facilitate eventual genetic engineering of this important biological control agent.
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The role of increased gonotrophic cycles in the establishment of Wolbachia in Anopheles populations. THEOR ECOL-NETH 2020. [DOI: 10.1007/s12080-020-00457-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Sinha A, Li Z, Sun L, Carlow CKS. Complete Genome Sequence of the Wolbachia wAlbB Endosymbiont of Aedes albopictus. Genome Biol Evol 2019; 11:706-720. [PMID: 30715337 PMCID: PMC6414309 DOI: 10.1093/gbe/evz025] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/29/2019] [Indexed: 12/21/2022] Open
Abstract
Wolbachia, an alpha-proteobacterium closely related to Rickettsia, is a maternally transmitted, intracellular symbiont of arthropods and nematodes. Aedes albopictus mosquitoes are naturally infected with Wolbachia strains wAlbA and wAlbB. Cell line Aa23 established from Ae. albopictus embryos retains only wAlbB and is a key model to study host–endosymbiont interactions. We have assembled the complete circular genome of wAlbB from the Aa23 cell line using long-read PacBio sequencing at 500× median coverage. The assembled circular chromosome is 1.48 megabases in size, an increase of more than 300 kb over the published draft wAlbB genome. The annotation of the genome identified 1,205 protein coding genes, 34 tRNA, 3 rRNA, 1 tmRNA, and 3 other ncRNA loci. The long reads enabled sequencing over complex repeat regions which are difficult to resolve with short-read sequencing. Thirteen percent of the genome comprised insertion sequence elements distributed throughout the genome, some of which cause pseudogenization. Prophage WO genes encoding some essential components of phage particle assembly are missing, while the remainder are found in five prophage regions/WO-like islands or scattered around the genome. Orthology analysis identified a core proteome of 535 orthogroups across all completed Wolbachia genomes. The majority of proteins could be annotated using Pfam and eggNOG analyses, including ankyrins and components of the Type IV secretion system. KEGG analysis revealed the absence of five genes in wAlbB which are present in other Wolbachia. The availability of a complete circular chromosome from wAlbB will enable further biochemical, molecular, and genetic analyses on this strain and related Wolbachia.
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Affiliation(s)
- Amit Sinha
- New England Biolabs, Ipswich, Massachusetts
| | - Zhiru Li
- New England Biolabs, Ipswich, Massachusetts
| | - Luo Sun
- New England Biolabs, Ipswich, Massachusetts
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Abstract
Wolbachia (Alphaproteobacteria, Rickettsiales) is an intraovarially transmitted symbiont of insects able to exert striking phenotypes, including reproductive manipulations and pathogen blocking. These phenotypes make Wolbachia a promising tool to combat mosquito-borne diseases. Although Wolbachia is present in the majority of terrestrial arthropods, including many disease vectors, it was considered absent from Anopheles gambiae mosquitos, the main vectors of malaria in sub-Saharan Africa. In 2014, Wolbachia sequences were detected in A. gambiae samples collected in Burkina Faso. Subsequently, similar evidence came from collections all over Africa, revealing a high Wolbachia 16S rRNA sequence diversity, low abundance, and a lack of congruence between host and symbiont phylogenies. Here, we reanalyze and discuss recent evidence on the presence of Wolbachia sequences in A. gambiae. We find that although detected at increasing frequencies, the unusual properties of these Wolbachia sequences render them insufficient to diagnose natural infections in A. gambiae Future studies should focus on uncovering the origin of Wolbachia sequence variants in Anopheles and seeking sequence-independent evidence for this new symbiosis. Understanding the ecology of Anopheles mosquitos and their interactions with Wolbachia will be key in designing successful, integrative approaches to limit malaria spread. Although the prospect of using Wolbachia to fight malaria is intriguing, the newly discovered strains do not bring it closer to realization.IMPORTANCEAnopheles gambiae mosquitos are the main vectors of malaria, threatening around half of the world's population. The bacterial symbiont Wolbachia can interfere with disease transmission by other important insect vectors, but until recently, it was thought to be absent from natural A. gambiae populations. Here, we critically analyze the genomic, metagenomic, PCR, imaging, and phenotypic data presented in support of the presence of natural Wolbachia infections in A. gambiae We find that they are insufficient to diagnose Wolbachia infections and argue for the need of obtaining robust data confirming basic Wolbachia characteristics in this system. Determining the Wolbachia infection status of Anopheles is critical due to its potential to influence Anopheles population structure and Plasmodium transmission.
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Affiliation(s)
- Ewa Chrostek
- Max Planck Institute for Infection Biology, Berlin, Germany
- Institute of Integrative Biology, University of Liverpool, United Kingdom
| | - Michael Gerth
- Institute of Integrative Biology, University of Liverpool, United Kingdom
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Martins-da-Silva A, Telleria EL, Batista M, Marchini FK, Traub-Csekö YM, Tempone AJ. Identification of Secreted Proteins Involved in Nonspecific dsRNA-Mediated Lutzomyia longipalpis LL5 Cell Antiviral Response. Viruses 2018; 10:v10010043. [PMID: 29346269 PMCID: PMC5795456 DOI: 10.3390/v10010043] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Revised: 12/04/2017] [Accepted: 12/05/2017] [Indexed: 02/07/2023] Open
Abstract
Hematophagous insects transmit infectious diseases. Sand flies are vectors of leishmaniasis, but can also transmit viruses. We have been studying immune responses of Lutzomyia longipalpis, the main vector of visceral leishmaniasis in the Americas. We identified a non-specific antiviral response in L. longipalpis LL5 embryonic cells when treated with non-specific double-stranded RNAs (dsRNAs). This response is reminiscent of interferon response in mammals. We are investigating putative effectors for this antiviral response. Secreted molecules have been implicated in immune responses, including interferon-related responses. We conducted a mass spectrometry analysis of conditioned medium from LL5 cells 24 and 48 h after dsRNA or mock treatment. We identified 304 proteins. At 24 h, 19 proteins had an abundance equal or greater than 2-fold change, while the levels of 17 proteins were reduced when compared to control cells. At the 48 h time point, these numbers were 33 and 71, respectively. The two most abundant secreted peptides at 24 h in the dsRNA-transfected group were phospholipid scramblase, an interferon-inducible protein that mediates antiviral activity, and forskolin-binding protein (FKBP), a member of the immunophilin family, which mediates the effect of immunosuppressive drugs. The transcription profile of most candidates did not follow the pattern of secreted protein abundance.
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Affiliation(s)
- Andrea Martins-da-Silva
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, Rio de Janeiro 21040-360, RJ, Brazil.
| | - Erich Loza Telleria
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, Rio de Janeiro 21040-360, RJ, Brazil.
| | - Michel Batista
- Laboratório de Genômica Funcional, Instituto Carlos Chagas-Fiocruz, Rua Prof. Algacyr Munhoz Mader 3775, Curitiba 81350-010, PR, Brazil.
- Plataforma Espectrometria de Massas-RPT02H, Instituto Carlos Chagas-Fiocruz, Rua Prof. Algacyr Munhoz Mader 3775, Curitiba 81350-010, PR, Brazil.
| | - Fabricio Klerynton Marchini
- Laboratório de Genômica Funcional, Instituto Carlos Chagas-Fiocruz, Rua Prof. Algacyr Munhoz Mader 3775, Curitiba 81350-010, PR, Brazil.
- Plataforma Espectrometria de Massas-RPT02H, Instituto Carlos Chagas-Fiocruz, Rua Prof. Algacyr Munhoz Mader 3775, Curitiba 81350-010, PR, Brazil.
| | - Yara Maria Traub-Csekö
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, Rio de Janeiro 21040-360, RJ, Brazil.
| | - Antonio Jorge Tempone
- Laboratório de Biologia Molecular de Parasitas e Vetores, Instituto Oswaldo Cruz-Fiocruz, Av. Brasil 4365, Rio de Janeiro 21040-360, RJ, Brazil.
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Espinosa MS, Virla EG, Cuozzo S. Wolbachia Infections Responsible for Thelytoky in Dryinid Wasps. The Case of Gonatopus bonaerensis Virla (Hymenoptera: Dryinidae). NEOTROPICAL ENTOMOLOGY 2017; 46:409-413. [PMID: 27988830 DOI: 10.1007/s13744-016-0475-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Accepted: 12/01/2016] [Indexed: 06/06/2023]
Abstract
We studied the occurrence of Wolbachia in the parasitoid Gonatopus bonaerensis Virla (Hymenoptera: Dryinidae). In order to verify the existence of natural infections in the parasitoid, a field survey was conducted. Identification of Wolbachia was performed on the basis of 16S rDNA, wsp_F1, and wsp_R1-sequences. After the detection of the bacteria, infected specimens of G. bonaerensis were treated with a solution of tetracycline. In Tucumán, parasitoids hold Wolbachia endosymbiont, which seems to control the wasp's reproduction in the nature turning it into thelytokous. The symbiont was identified as the Wolbachia sp. wRi strain. The cure of infected unfertilized females determined the normal arrhenotokous parthenogenesis and the production of male offspring. As a consequence of this procedure, the male of G. bonaerensis is described for the first time.
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Affiliation(s)
- M S Espinosa
- Univ Nacional de Chilecito (UNDEC), Chilecito, La Rioja, Argentina
| | - E G Virla
- Instituto de Entomología, Fund. M. Lillo, Miguel Lillo 251, 4000, San Miguel de Tucumán, Argentina.
- PROIMI- Biotecnología - CONICET, San Miguel de Tucumán, Argentina.
| | - S Cuozzo
- PROIMI- Biotecnología - CONICET, San Miguel de Tucumán, Argentina
- Facultad de Cs. Naturales e Inst. M. Lillo, Univ. Nac. de Tucumán, San Miguel de Tucumán, Argentina
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Ma WJ, Schwander T. Patterns and mechanisms in instances of endosymbiont-induced parthenogenesis. J Evol Biol 2017; 30:868-888. [PMID: 28299861 DOI: 10.1111/jeb.13069] [Citation(s) in RCA: 69] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 03/05/2017] [Accepted: 03/10/2017] [Indexed: 12/11/2022]
Abstract
Female-producing parthenogenesis can be induced by endosymbionts that increase their transmission by manipulating host reproduction. Our literature survey indicates that such endosymbiont-induced parthenogenesis is known or suspected in 124 host species from seven different arthropod taxa, with Wolbachia as the most frequent endosymbiont (in 56-75% of host species). Most host species (81%, 100 out of 124) are characterized by haplo-diploid sex determination, but a strong ascertainment bias likely underestimates the frequency of endosymbiont-induced parthenogenesis in hosts with other sex determination systems. In at least one taxon, hymenopterans, endosymbionts are a significant driver of transitions from sexual to parthenogenetic reproduction, with one-third of lineages being parthenogenetic as a consequence of endosymbiont infection. Endosymbiont-induced parthenogenesis appears to facilitate the maintenance of reproductive polymorphism: at least 50% of species comprise both sexual (uninfected) and parthenogenetic (infected) strains. These strains feature distribution differences similar to the ones documented for lineages with genetically determined parthenogenesis, with endosymbiont-induced parthenogens occurring at higher latitudes than their sexual relatives. Finally, although gamete duplication is often considered as the main mechanism for endosymbiont-induced parthenogenesis, it underlies parthenogenesis in only half of the host species studied thus far. We point out caveats in the methods used to test for endosymbiont-induced parthenogenesis and suggest specific approaches that allow for firm conclusions about the involvement of endosymbionts in the origin of parthenogenesis.
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Affiliation(s)
- W-J Ma
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - T Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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Identification and Characterization of a Candidate Wolbachia pipientis Type IV Effector That Interacts with the Actin Cytoskeleton. mBio 2016; 7:mBio.00622-16. [PMID: 27381293 PMCID: PMC4958246 DOI: 10.1128/mbio.00622-16] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
UNLABELLED Many bacteria live as intracellular symbionts, causing persistent infections within insects. One extraordinarily common infection is that of Wolbachia pipientis, which infects 40% of insect species and induces reproductive effects. The bacteria are passed from generation to generation both vertically (through the oocyte) and horizontally (by environmental transmission). Maintenance of the infection within Drosophila melanogaster is sensitive to the regulation of actin, as Wolbachia inefficiently colonizes strains hemizygous for the profilin or villin genes. Therefore, we hypothesized that Wolbachia must depend on the host actin cytoskeleton. In this study, we identify and characterize a Wolbachia protein (WD0830) that is predicted to be secreted by the bacterial parasite. Expression of WD0830 in a model eukaryote (the yeast Saccharomyces cerevisiae) induces a growth defect associated with the appearance of aberrant, filamentous structures which colocalize with rhodamine-phalloidin-stained actin. Purified WD0830 bundles actin in vitro and cosediments with actin filaments, suggesting a direct interaction of the two proteins. We characterized the expression of WD0830 throughout Drosophila development and found it to be upregulated in third-instar larvae, peaking in early pupation, during the critical formation of adult tissues, including the reproductive system. In transgenic flies, heterologously expressed WD0830 localizes to the developing oocyte. Additionally, overexpression of WD0830 results in increased Wolbachia titers in whole flies, in stage 9 and 10 oocytes, and in embryos, compared to controls, suggesting that the protein may facilitate Wolbachia's replication or transmission. Therefore, this candidate secreted effector may play a role in Wolbachia's infection of and persistence within host niches. IMPORTANCE The obligate intracellular Wolbachia pipientis is a ubiquitous alphaproteobacterial symbiont of arthropods and nematodes and is related to the rickettsial pathogens Ehrlichia spp. and Anaplasma spp. Studies of Wolbachia cell biology suggest that this bacterium relies on host actin for efficient proliferation and transmission between generations. Here, we identified and characterized a Wolbachia protein that localizes to and manipulates the eukaryotic actin cytoskeleton, is expressed by Wolbachia during host development, and alters Wolbachia titers and localization in transgenic fruit flies. We hypothesize that WD0830 may be utilized by the bacterium to facilitate replication in or invasion of different niches during host development.
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Hughes GL, Dodson BL, Johnson RM, Murdock CC, Tsujimoto H, Suzuki Y, Patt AA, Cui L, Nossa CW, Barry RM, Sakamoto JM, Hornett EA, Rasgon JL. Native microbiome impedes vertical transmission of Wolbachia in Anopheles mosquitoes. Proc Natl Acad Sci U S A 2014; 111:12498-503. [PMID: 25114252 PMCID: PMC4151774 DOI: 10.1073/pnas.1408888111] [Citation(s) in RCA: 166] [Impact Index Per Article: 16.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Over evolutionary time, Wolbachia has been repeatedly transferred between host species contributing to the widespread distribution of the symbiont in arthropods. For novel infections to be maintained, Wolbachia must infect the female germ line after being acquired by horizontal transfer. Although mechanistic examples of horizontal transfer exist, there is a poor understanding of factors that lead to successful vertical maintenance of the acquired infection. Using Anopheles mosquitoes (which are naturally uninfected by Wolbachia) we demonstrate that the native mosquito microbiota is a major barrier to vertical transmission of a horizontally acquired Wolbachia infection. After injection into adult Anopheles gambiae, some strains of Wolbachia invade the germ line, but are poorly transmitted to the next generation. In Anopheles stephensi, Wolbachia infection elicited massive blood meal-induced mortality, preventing development of progeny. Manipulation of the mosquito microbiota by antibiotic treatment resulted in perfect maternal transmission at significantly elevated titers of the wAlbB Wolbachia strain in A. gambiae, and alleviated blood meal-induced mortality in A. stephensi enabling production of Wolbachia-infected offspring. Microbiome analysis using high-throughput sequencing identified that the bacterium Asaia was significantly reduced by antibiotic treatment in both mosquito species. Supplementation of an antibiotic-resistant mutant of Asaia to antibiotic-treated mosquitoes completely inhibited Wolbachia transmission and partly contributed to blood meal-induced mortality. These data suggest that the components of the native mosquito microbiota can impede Wolbachia transmission in Anopheles. Incompatibility between the microbiota and Wolbachia may in part explain why some hosts are uninfected by this endosymbiont in nature.
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Affiliation(s)
| | | | | | | | | | | | | | | | - Carlos W Nossa
- Department of Ecology and Evolutionary Biology, Rice University, Houston, TX 77005; and
| | | | | | - Emily A Hornett
- Biology, Center for Infectious Disease Dynamics, and the Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802; The Department of Zoology, University of Cambridge, Cambridge CB2 3EJ, United Kingdom
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14
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Hughes GL, Rasgon JL. Transinfection: a method to investigate Wolbachia-host interactions and control arthropod-borne disease. INSECT MOLECULAR BIOLOGY 2014; 23:141-51. [PMID: 24329998 PMCID: PMC3949162 DOI: 10.1111/imb.12066] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The bacterial endosymbiont Wolbachia manipulates arthropod host biology in numerous ways, including sex ratio distortion and differential offspring survival. These bacteria infect a vast array of arthropods, some of which pose serious agricultural and human health threats. Wolbachia-mediated phenotypes such as cytoplasmic incompatibility and/or pathogen interference can be used for vector and disease control; however, many medically important vectors and important agricultural species are uninfected or are infected with strains of Wolbachia that do not elicit phenotypes desirable for disease or pest control. The ability to transfer strains of Wolbachia into new hosts (transinfection) can create novel Wolbachia-host associations. Transinfection has two primary benefits. First, Wolbachia-host interactions can be examined to tease apart the influence of the host and bacteria on phenotypes. Second, desirable phenotypes induced by Wolbachia in a particular insect can be transferred to another recipient host. This can allow the manipulation of insect populations that transmit pathogens or detrimentally affect agriculture. As such, transinfection is a valuable tool to explore Wolbachia biology and control arthropod-borne disease. The present review summarizes what is currently known about Wolbachia transinfection methods and applications. We also provide a comprehensive list of published successful and unsuccessful Wolbachia transinfection attempts.
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Affiliation(s)
- G L Hughes
- The Huck Institutes of The Life Sciences, The Center for Infectious Disease Dynamics, Pennsylvania State University, University Park, PA, USA; Department of Entomology, Pennsylvania State University, University Park, PA, USA
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15
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Temperature alters Plasmodium blocking by Wolbachia. Sci Rep 2014; 4:3932. [PMID: 24488176 PMCID: PMC3909897 DOI: 10.1038/srep03932] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2013] [Accepted: 01/07/2014] [Indexed: 12/31/2022] Open
Abstract
Very recently, the Asian malaria vector (Anopheles stephensi) was stably transinfected with the wAlbB strain of Wolbachia, inducing refractoriness to the human malaria parasite Plasmodium falciparum. However, conditions in the field can differ substantially from those in the laboratory. We use the rodent malaria P. yoelii, and somatically transinfected An. stephensi as a model system to investigate whether the transmission blocking potential of wAlbB is likely to be robust across different thermal environments. wAlbB reduced malaria parasite prevalence and oocyst intensity at 28°C. At 24°C there was no effect on prevalence but a marked increase in oocyst intensity. At 20°C, wAlbB had no effect on prevalence or intensity. Additionally, we identified a novel effect of wAlbB that resulted in reduced sporozoite development across temperatures, counterbalancing the oocyst enhancement at 24°C. Our results demonstrate complex effects of temperature on the Wolbachia-malaria interaction, and suggest the impacts of transinfection might vary across diverse environments.
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Beckmann JF, Fallon AM. Detection of the Wolbachia protein WPIP0282 in mosquito spermathecae: implications for cytoplasmic incompatibility. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:867-78. [PMID: 23856508 PMCID: PMC3839623 DOI: 10.1016/j.ibmb.2013.07.002] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2013] [Revised: 06/24/2013] [Accepted: 07/04/2013] [Indexed: 05/25/2023]
Abstract
Cytoplasmic incompatibility (CI) is a conditional sterility induced by the bacterium Wolbachia pipientis that infects reproductive tissues in many arthropods. Although CI provides a potential tool to control insect vectors of arthropod-borne diseases, the molecular basis for CI induction is unknown. We hypothesized that a Wolbachia-encoded, CI-inducing factor would be enriched in sperm recovered from spermathecae of female mosquitoes. Using SDS-PAGE and mass spectrometry, we detected peptides from the 56 kDa hypothetical protein, encoded by wPip_0282, associated with sperm transferred to females by Wolbachia infected males. We also detected peptides from the same protein in Wolbachia infected ovaries. Homologs of wPip_0282 and the co-transcribed downstream gene, wPip_0283, occur as multiple divergent copies in genomes of CI-inducing strains of Wolbachia. The operon is located in a genomic context that includes mobile genetic elements. The absence of wPip_0282 and wPip_0283 homologs from genomes of Wolbachia in filarial nematodes, as well as other members of the Rickettsiales, suggests a role as a candidate CI effector.
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Affiliation(s)
- John F Beckmann
- Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA.
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Ye YH, Woolfit M, Rancès E, O'Neill SL, McGraw EA. Wolbachia-associated bacterial protection in the mosquito Aedes aegypti. PLoS Negl Trop Dis 2013; 7:e2362. [PMID: 23951381 PMCID: PMC3738474 DOI: 10.1371/journal.pntd.0002362] [Citation(s) in RCA: 90] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2013] [Accepted: 06/30/2013] [Indexed: 12/15/2022] Open
Abstract
Background Wolbachia infections confer protection for their insect hosts against a range of pathogens including bacteria, viruses, nematodes and the malaria parasite. A single mechanism that might explain this broad-based pathogen protection is immune priming, in which the presence of the symbiont upregulates the basal immune response, preparing the insect to defend against subsequent pathogen infection. A study that compared natural Wolbachia infections in Drosophila melanogaster with the mosquito vector Aedes aegypti artificially transinfected with the same strains has suggested that innate immune priming may only occur in recent host-Wolbachia associations. This same study also revealed that while immune priming may play a role in viral protection it cannot explain the entirety of the effect. Methodology/Findings Here we assess whether the level of innate immune priming induced by different Wolbachia strains in A. aegypti is correlated with the degree of protection conferred against bacterial pathogens. We show that Wolbachia strains wMel and wMelPop, currently being tested for field release for dengue biocontrol, differ in their protective abilities. The wMelPop strain provides stronger, more broad-based protection than wMel, and this is likely explained by both the higher induction of immune gene expression and the strain-specific activation of particular genes. We also show that Wolbachia densities themselves decline during pathogen infection, likely as a result of the immune induction. Conclusions/Significance This work shows a correlation between innate immune priming and bacterial protection phenotypes. The ability of the Toll pathway, melanisation and antimicrobial peptides to enhance viral protection or to provide the basis of malaria protection should be further explored in the context of this two-strain comparison. This work raises the questions of whether Wolbachia may improve the ability of wild mosquitoes to survive pathogen infection or alter the natural composition of gut flora, and thus have broader consequences for host fitness. Wolbachia is a commonly occurring bacterium or symbiont that lives inside the cells of insects. Recently, Wolbachia was artificially introduced into the mosquito vector dengue virus that was naturally Wolbachia-free. Wolbachia limits the growth of a range of pathogens transmitted to humans, including viruses, bacteria and parasites inside the mosquito. This “pathogen protection” forms the basis of field trials to determine if releasing Wolbachia into wild mosquito populations could reduce dengue virus incidence in humans. The basis of pathogen protection is not fully understood. Previous work suggests that the symbiont may activate the basal immune response, preparing the insect to defend itself against subsequent pathogen infection. Here we infect mosquitoes harbouring Wolbachia with a range of bacterial pathogens as a means to understand the nature of protection. We show that different Wolbachia strains vary in their ability to limit pathogen growth and that this correlates with the degree to which the Wolbachia activates the host immune response. These findings may assist with Wolbachia strain selection for future open field release and raise the question whether Wolbachia might provide a fitness advantage to mosquitoes in the wild by limiting their death due to bacterial infection.
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Affiliation(s)
- Yixin H. Ye
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Megan Woolfit
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Edwige Rancès
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Scott L. O'Neill
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
| | - Elizabeth A. McGraw
- School of Biological Sciences, Monash University, Clayton, Victoria, Australia
- * E-mail:
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Beckmann JF, Markowski TW, Witthuhn BA, Fallon AM. Detection of the Wolbachia-encoded DNA binding protein, HU beta, in mosquito gonads. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:272-279. [PMID: 23287400 PMCID: PMC3578164 DOI: 10.1016/j.ibmb.2012.12.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2012] [Revised: 12/14/2012] [Accepted: 12/18/2012] [Indexed: 05/31/2023]
Abstract
Wolbachia are obligate intracellular bacteria that cause cytoplasmic incompatibility in mosquitoes. In an incompatible cross, eggs of uninfected females fail to hatch when fertilized by sperm from infected males. We used polyacrylamide gel electrophoresis and tandem mass spectrometry to identify Wolbachia proteins in infected mosquito gonads. These included surface proteins with masses of 25 and 18 kDa and the DNA binding protein, HU beta. Using reverse transcriptase polymerase chain reaction, we showed that the HU gene is transcribed in Wolbachia-infected Culex pipiens and Aedes albopictus mosquitoes. We sequenced HU genes from four Wolbachia strains and compared deduced protein sequences with additional homologs from the databases. Among the Rickettsiales, Wolbachia HU has distinct N- and C-terminal basic/acidic amino acid motifs as well as a pair of conserved, cysteine residues.
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Affiliation(s)
- John F Beckmann
- Department of Entomology, University of Minnesota, St. Paul, MN 55108, USA.
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19
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Sampath KS, Puttaraju HP. Improvised microinjection technique for mosquito vectors. Indian J Med Res 2012; 136:971-8. [PMID: 23391792 PMCID: PMC3612326] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
BACKGROUND & OBJECTIVES Bio-manipulation technique is of primary importance during the development of transgenic mosquitoes. The study describes the variable factors that influence the viability of medically important mosquito vectors during microinjection. METHODS Three mosquito vectors belonging to the genus Aedes, Anopheles and Culex were microinjected at different developmental stages of their life cycle viz., egg, larvae, pupae and adult. RESULTS The improvisations revealed an increased survivability of biomanipulated mosquitoes during the embryonic and adult microinjection. The study of injecting larvae and pupae resulted in poor survivability. INTERPRETATION & CONCLUSIONS The microinjection protocol was successfully tested on three important mosquito vectors. The critical period after biomanipulation which contributes heavily for the survivability factor was evaluated. The results provide a common protocol for biomanipulation of three mosquito vectors with enhanced survivability.
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Affiliation(s)
- Kumar S. Sampath
- Department of Sericulture & Division of Biological Sciences, School of Natural Sciences, Bangalore University, Bangalore, India
| | - H. P. Puttaraju
- Department of Sericulture & Division of Biological Sciences, School of Natural Sciences, Bangalore University, Bangalore, India,Reprint requests: Dr Puttaraju Hosagavi Puttegowda, Department of Sericulture & Division of Biological SciencesSchool of Natural Science, Bangalore University, Bangalore 560 056, India e-mail: ;
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Hughes GL, Pike AD, Xue P, Rasgon JL. Invasion of Wolbachia into Anopheles and other insect germlines in an ex vivo organ culture system. PLoS One 2012; 7:e36277. [PMID: 22558418 PMCID: PMC3340357 DOI: 10.1371/journal.pone.0036277] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 04/01/2012] [Indexed: 11/19/2022] Open
Abstract
The common bacterial endosymbiont Wolbachia manipulates its host's reproduction to promote its own maternal transmission, and can interfere with pathogen development in many insects making it an attractive agent for the control of arthropod-borne disease. However, many important species, including Anopheles mosquitoes, are uninfected. Wolbachia can be artificially transferred between insects in the laboratory but this can be a laborious and sometimes fruitless process. We used a simple ex vivo culturing technique to assess the suitability of Wolbachia-host germline associations. Wolbachia infects the dissected germline tissue of multiple insect species when the host tissue and bacteria are cultured together. Ovary and testis infection occurs in a density-dependent manner. Wolbachia strains are more capable of invading the germline of their native or closely related rather than divergent hosts. The ability of Wolbachia to associate with the germline of novel hosts is crucial for the development of stably-transinfected insect lines. Rapid assessment of the suitability of a strain-host combination prior to transinfection may dictate use of a particular Wolbachia strain. Furthermore, the cultured germline tissues of two major Anopheline vectors of Plasmodium parasites are susceptible to Wolbachia infection. This finding further enhances the prospect of using Wolbachia for the biological control of malaria.
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Affiliation(s)
- Grant L. Hughes
- The Department of Entomology, Center for Infectious Disease Dynamics and Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
| | - Andrew D. Pike
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Ping Xue
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jason L. Rasgon
- The Department of Entomology, Center for Infectious Disease Dynamics and Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, Pennsylvania, United States of America
- * E-mail:
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Abdul-Ghani R, Al-Mekhlafi AM, Alabsi MS. Microbial control of malaria: biological warfare against the parasite and its vector. Acta Trop 2012; 121:71-84. [PMID: 22100545 DOI: 10.1016/j.actatropica.2011.11.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2011] [Revised: 10/31/2011] [Accepted: 11/04/2011] [Indexed: 01/31/2023]
Abstract
Microbial applications in malaria transmission control have drawn global attention. Mosquito midgut microbiota can modulate vector immunity and block Plasmodium development. Paratransgenic manipulation of bacterial symbionts and Wolbachia can affect reproductive characteristics of mosquitoes. Bacillus-based biolarvicides can control mosquito larvae in different breeding habitats, but their effectiveness differs according to the type of formulation applied, and the physical and ecological conditions of the environment. Entomopathogenic fungi show promise as effective and evolution-proof agents against adult mosquitoes. In addition, transgenic fungi can express anti-plasmodial effector molecules that can target the parasite inside its vector. Despite showing effectiveness in domestic environments as well as against insecticide-resistant mosquitoes, claims towards their deployability in the field and their possible use in integrated vector management programmes have yet to be investigated. Viral pathogens show efficacy in the interruption of sporogonic development of the parasite, and protozoal pathogens exert direct pathogenic potential on larvae and adults with substantial effects on mosquito longevity and fecundity. However, the technology required for their isolation and maintenance impedes their field application. Many agents show promising findings; however, the question remains about the epidemiologic reality of these approaches because even those that have been tried under field conditions still have certain limitations. This review addresses aspects of the microbial control of malaria between proof-of-concept and epidemiologic reality.
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Wolbachia strain wAlbB enhances infection by the rodent malaria parasite Plasmodium berghei in Anopheles gambiae mosquitoes. Appl Environ Microbiol 2011; 78:1491-5. [PMID: 22210220 DOI: 10.1128/aem.06751-11] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Wolbachia, a common bacterial endosymbiont of insects, has been shown to protect its hosts against a wide range of pathogens. However, not all strains exert a protective effect on their host. Here we assess the effects of two divergent Wolbachia strains, wAlbB from Aedes albopictus and wMelPop from Drosophila melanogaster, on the vector competence of Anopheles gambiae challenged with Plasmodium berghei. We show that the wAlbB strain significantly increases P. berghei oocyst levels in the mosquito midgut while wMelPop modestly suppresses oocyst levels. The wAlbB strain is avirulent to mosquitoes while wMelPop is moderately virulent to mosquitoes pre-blood meal and highly virulent after mosquitoes have fed on mice. These various effects on P. berghei levels suggest that Wolbachia strains differ in their interactions with the host and/or pathogen, and these differences could be used to dissect the molecular mechanisms that cause interference of pathogen development in mosquitoes.
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Crotti E, Balloi A, Hamdi C, Sansonno L, Marzorati M, Gonella E, Favia G, Cherif A, Bandi C, Alma A, Daffonchio D. Microbial symbionts: a resource for the management of insect-related problems. Microb Biotechnol 2011; 5:307-17. [PMID: 22103294 PMCID: PMC3821675 DOI: 10.1111/j.1751-7915.2011.00312.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Microorganisms establish with their animal hosts close interactions. They are involved in many aspects of the host life, physiology and evolution, including nutrition, reproduction, immune homeostasis, defence and speciation. Thus, the manipulation and the exploitation the microbiota could result in important practical applications for the development of strategies for the management of insect-related problems. This approach, defined as 'Microbial Resource Management' (MRM), has been applied successfully in various environments and ecosystems, as wastewater treatments, prebiotics in humans, anaerobic digestion and so on. MRM foresees the proper management of the microbial resource present in a given ecosystem in order to solve practical problems through the use of microorganisms. In this review we present an interesting field for application for MRM concept, i.e. the microbial communities associated with arthropods and nematodes. Several examples related to this field of applications are presented. Insect microbiota can be manipulated: (i) to control insect pests for agriculture; (ii) to control pathogens transmitted by insects to humans, animals and plants; (iii) to protect beneficial insects from diseases and stresses. Besides, we prospect further studies aimed to verify, improve and apply MRM by using the insect-symbiont ecosystem as a model.
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Affiliation(s)
- Elena Crotti
- Dipartimento di Scienze e Tecnologie Alimentari e Microbiologiche, Università degli Studi di Milano, 20133 Milan, Italy
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Zhang X, Ren X, Norris DE, Rasgon JL. Distribution and infection frequency of 'Candidatus Rickettsia amblyommii' in Maryland populations of the lone star tick (Amblyomma americanum) and culture in an Anopheles gambiae mosquito cell line. Ticks Tick Borne Dis 2011; 3:38-42. [PMID: 22309857 DOI: 10.1016/j.ttbdis.2011.09.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2011] [Revised: 09/28/2011] [Accepted: 09/29/2011] [Indexed: 10/15/2022]
Abstract
Amblyomma americanum (the lone star tick) is a broadly distributed tick that transmits multiple pathogens of humans and domestic animals. 'Candidatus Rickettsia amblyommii' is a spotted-fever group rickettsial species that is potentially associated with human disease. In 2008 and 2009, we assayed over 500 unfed adult ticks from 19 Maryland populations for the presence of 'Candidatus R. amblyommii'. Infection frequencies ranged from 33% to 100%, with an average infection rate of 60% in 2008 and 69% in 2009. Infection frequencies did not differ statistically between sexes. To develop a system in which to study 'Candidatus R. amblyommii' in the laboratory, we used a cell line developed from Anopheles gambiae mosquitoes (Sua5B) to isolate and culture 'Candidatus R. amblyommii' from field-collected A. americanum ticks from 2 localities in Maryland. After infection, Sua5B cells were infected for more than 40 passages. Infection was confirmed by Rickettsia-specific PCR, gene sequencing, and Rickettsia-specific fluorescence in situ hybridization (FISH). These data show that 'Candidatus R. amblyommii' is widespread in Maryland A. americanum populations and that Sua5B cells are a useful tool for culturing Rickettsia infections from wild ticks.
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Affiliation(s)
- Xing Zhang
- The W. Harry Feinstone Dept. of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, MD 21205, USA
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25
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Hughes GL, Koga R, Xue P, Fukatsu T, Rasgon JL. Wolbachia infections are virulent and inhibit the human malaria parasite Plasmodium falciparum in Anopheles gambiae. PLoS Pathog 2011; 7:e1002043. [PMID: 21625582 PMCID: PMC3098226 DOI: 10.1371/journal.ppat.1002043] [Citation(s) in RCA: 239] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 03/14/2011] [Indexed: 11/18/2022] Open
Abstract
Endosymbiotic Wolbachia bacteria are potent modulators of pathogen infection and transmission in multiple naturally and artificially infected insect species, including important vectors of human pathogens. Anopheles mosquitoes are naturally uninfected with Wolbachia, and stable artificial infections have not yet succeeded in this genus. Recent techniques have enabled establishment of somatic Wolbachia infections in Anopheles. Here, we characterize somatic infections of two diverse Wolbachia strains (wMelPop and wAlbB) in Anopheles gambiae, the major vector of human malaria. After infection, wMelPop disseminates widely in the mosquito, infecting the fat body, head, sensory organs and other tissues but is notably absent from the midgut and ovaries. Wolbachia initially induces the mosquito immune system, coincident with initial clearing of the infection, but then suppresses expression of immune genes, coincident with Wolbachia replication in the mosquito. Both wMelPop and wAlbB significantly inhibit Plasmodium falciparum oocyst levels in the mosquito midgut. Although not virulent in non-bloodfed mosquitoes, wMelPop exhibits a novel phenotype and is extremely virulent for approximately 12-24 hours post-bloodmeal, after which surviving mosquitoes exhibit similar mortality trajectories to control mosquitoes. The data suggest that if stable transinfections act in a similar manner to somatic infections, Wolbachia could potentially be used as part of a strategy to control the Anopheles mosquitoes that transmit malaria.
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Affiliation(s)
- Grant L. Hughes
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, United States of America
| | - Ryuichi Koga
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Ping Xue
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, United States of America
| | - Takema Fukatsu
- National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Japan
| | - Jason L. Rasgon
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, United States of America
- * E-mail:
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26
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Wolbachia and the biological control of mosquito-borne disease. EMBO Rep 2011; 12:508-18. [PMID: 21546911 DOI: 10.1038/embor.2011.84] [Citation(s) in RCA: 255] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Accepted: 04/12/2011] [Indexed: 12/22/2022] Open
Abstract
Mosquito-borne diseases such as malaria, dengue fever and filariasis cause an enormous health burden to people living in tropical and subtropical regions of the world. Despite years of intense effort to control them, many of these diseases are increasing in prevalence, geographical distribution and severity, and options to control them are limited. The transinfection of mosquitos with the maternally inherited, endosymbiotic bacteria Wolbachia is a promising new biocontrol approach. Fruit fly Wolbachia strains can invade and sustain themselves in mosquito populations, reduce adult lifespan, affect mosquito reproduction and interfere with pathogen replication. Wolbachia-infected Aedes aegypti mosquitoes have been released in areas of Australia in which outbreaks of dengue fever occur, as a prelude to the application of this technology in dengue-endemic areas of south-east Asia.
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27
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Wolbachia infections in Anopheles gambiae cells: transcriptomic characterization of a novel host-symbiont interaction. PLoS Pathog 2011; 7:e1001296. [PMID: 21379333 PMCID: PMC3040664 DOI: 10.1371/journal.ppat.1001296] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2010] [Accepted: 01/18/2011] [Indexed: 01/05/2023] Open
Abstract
The endosymbiotic bacterium Wolbachia is being investigated as a potential control agent in several important vector insect species. Recent studies have shown that Wolbachia can protect the insect host against a wide variety of pathogens, resulting in reduced transmission of parasites and viruses. It has been proposed that compromised vector competence of Wolbachia-infected insects is due to up-regulation of the host innate immune system or metabolic competition. Anopheles mosquitoes, which transmit human malaria parasites, have never been found to harbor Wolbachia in nature. While transient somatic infections can be established in Anopheles, no stable artificially-transinfected Anopheles line has been developed despite numerous attempts. However, cultured Anopheles cells can be stably infected with multiple Wolbachia strains such as wAlbB from Aedes albopictus, wRi from Drosophila simulans and wMelPop from Drosophila melanogaster. Infected cell lines provide an amenable system to investigate Wolbachia-Anopheles interactions in the absence of an infected mosquito strain. We used Affymetrix GeneChip microarrays to investigate the effect of wAlbB and wRi infection on the transcriptome of cultured Anopheles Sua5B cells, and for a subset of genes used quantitative PCR to validate results in somatically-infected Anopheles mosquitoes. Wolbachia infection had a dramatic strain-specific effect on gene expression in this cell line, with almost 700 genes in total regulated representing a diverse array of functional classes. Very strikingly, infection resulted in a significant down-regulation of many immune, stress and detoxification-related transcripts. This is in stark contrast to the induction of immune genes observed in other insect hosts. We also identified genes that may be potentially involved in Wolbachia-induced reproductive and pathogenic phenotypes. Somatically-infected mosquitoes had similar responses to cultured cells. The data show that Wolbachia has a profound and unique effect on Anopheles gene expression in cultured cells, and has important implications for mechanistic understanding of Wolbachia-induced phenotypes and potential novel strategies to control malaria.
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Kent BN, Bordenstein SR. Phage WO of Wolbachia: lambda of the endosymbiont world. Trends Microbiol 2010; 18:173-81. [PMID: 20083406 DOI: 10.1016/j.tim.2009.12.011] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2009] [Revised: 12/07/2009] [Accepted: 12/16/2009] [Indexed: 11/15/2022]
Abstract
The discovery of an extraordinarily high level of mobile elements in the genome of Wolbachia, a widespread arthropod and nematode endosymbiont, suggests that this bacterium could be an excellent model for assessing the evolution and function of mobile DNA in specialized bacteria. In this paper, we discuss how studies on the temperate bacteriophage WO of Wolbachia have revealed unexpected levels of genomic flux and are challenging previously held views about the clonality of obligate intracellular bacteria. We also discuss the roles this phage might play in the Wolbachia-arthropod symbiosis and infer how this research can be translated to combating human diseases vectored by arthropods. We expect that this temperate phage will be a preeminent model system to understand phage genetics, evolution and ecology in obligate intracellular bacteria. In this sense, phage WO might be likened to phage lambda of the endosymbiont world.
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Affiliation(s)
- Bethany N Kent
- Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA.
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Voronin D, Tran-Van V, Potier P, Mavingui P. Transinfection and growth discrepancy of Drosophila Wolbachia strain wMel in cell lines of the mosquito Aedes albopictus. J Appl Microbiol 2009; 108:2133-41. [PMID: 19951376 DOI: 10.1111/j.1365-2672.2009.04621.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
AIM The Wolbachia strain wMel can protect Drosophila melanogaster against pathogenic RNA viruses. To analyse the potential of this inhibitory effect against arboviruses vectorized by these mosquitoes, we here first transinfected the Aedes albopictus Aa23 and C6/36 cell lines with the Wolbachia strain wMel and then monitored their infection dynamics. METHODS AND RESULTS Wolbachia strain wMel was transferred into A. albopictus Aa23 and C6/36 cell lines using the shell vial technique. The presence of the bacterium in the transinfected cells was monitored by quantitative PCR and fluorescence in situ hybridization. Bacteria could be detected in the cytoplasm of both the Aa23 and C6/36 cell lines. However, the dynamics and stability of the bacterial infection differed depending on the initial cell background. The Aa23 cell line, which had been treated with a tetracycline antibiotic 2 years previously to eliminate its natural Wolbachia wAlbB-infecting strain, lost the introduced Wolbachia wMel strain after 12 passages postinfection. In contrast, the C6/36 cell line, which had originally been aposymbiotic, displayed a stable infection with Wolbachia wMel. The bacterial density in C6/36 was greater than that of the A. albopictus RML12 cell line from which the wMel strain had originated. CONCLUSIONS Transient or persistent transinfection of A. albopictus Aa23 and C6/36 cell lines with Wolbachia wMel strain was achieved. The results indicate the influence of the genetic background of mosquito cells in maintaining Wolbachia originating from a distant dipteral host. SIGNIFICANCE AND IMPACT OF THE STUDY The cell model built here can now be used to investigate the viral inhibitory effect of the Wolbachia wMel strain against arboviruses such as dengue and chikungunya, which are transmitted by the mosquito A. albopictus.
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The virulent Wolbachia strain wMelPop efficiently establishes somatic infections in the malaria vector Anopheles gambiae. Appl Environ Microbiol 2009; 75:3373-6. [PMID: 19329661 DOI: 10.1128/aem.00207-09] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Wolbachia pipientis bacteria are maternally inherited endosymbionts that are of interest to control the Anopheles mosquito vectors of malaria. Wolbachia does not infect Anopheles mosquitoes in nature, although cultured Anopheles cells can be infected. Here, we show that the virulent Wolbachia strain wMelPop can survive and replicate when injected into female Anopheles gambiae adults, but the somatic infections established are avirulent. These in vivo data suggest that stable Wolbachia infections of Anopheles may be possible.
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Proteasome activity in a naïve mosquito cell line infected with Wolbachia pipientis wAlbB. In Vitro Cell Dev Biol Anim 2009; 45:460-6. [PMID: 19296184 DOI: 10.1007/s11626-009-9193-6] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2008] [Accepted: 02/16/2009] [Indexed: 10/21/2022]
Abstract
We used Wolbachia pipientis strain wAlbB from Aedes albopictus Aa23 cells to infect clonal Ae. albopictus TK-6 cells, which are resistant to 5-bromodeoxyuridine. Infected TK-6 cells were cultured in medium containing 5-bromodeoxyuridine to select against Aa23 cells that might have persisted in the inoculum. Infected TK-6 lines retained the Wolbachia infection for 5 mo, indicating that their metabolic processes support Wolbachia growth and multiplication. To investigate early events after Wolbachia infection, we labeled infected cells with (35)S[methionine/cysteine]. Patterns of labeled proteins on sodium dodecyl sulfate gels were similar in control and infected cells, with the exception of a 29-kDa protein. Tandem mass spectrometry revealed that the 29-kDa band included alpha and beta subunits of the 26S proteasome. Independent confirmation of the up-regulation of the proteasome was established by probing Western blots with a monoclonal antibody to the proteasome-associated co-factor, ubiquitin. Wolbachia's loss of metabolic pathways for the synthesis of most amino acids and retention of pathways for their uptake and metabolism suggest that proteasome activation provides a mechanism whereby controlled degradation of intracellular host proteins would increase availability of amino acids to support establishment and maintenance of the Wolbachia infection.
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McMeniman CJ, Lane AM, Fong AWC, Voronin DA, Iturbe-Ormaetxe I, Yamada R, McGraw EA, O'Neill SL. Host adaptation of a Wolbachia strain after long-term serial passage in mosquito cell lines. Appl Environ Microbiol 2008; 74:6963-9. [PMID: 18836024 PMCID: PMC2583474 DOI: 10.1128/aem.01038-08] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2008] [Accepted: 09/22/2008] [Indexed: 11/20/2022] Open
Abstract
The horizontal transfer of the bacterium Wolbachia pipientis between invertebrate hosts hinges on the ability of Wolbachia to adapt to new intracellular environments. The experimental transfer of Wolbachia between distantly related host species often results in the loss of infection, presumably due to an inability of Wolbachia to adapt quickly to the new host. To examine the process of adaptation to a novel host, we transferred a life-shortening Wolbachia strain, wMelPop, from the fruit fly Drosophila melanogaster into a cell line derived from the mosquito Aedes albopictus. After long-term serial passage in this cell line, we transferred the mosquito-adapted wMelPop into cell lines derived from two other mosquito species, Aedes aegypti and Anopheles gambiae. After a prolonged period of serial passage in mosquito cell lines, wMelPop was reintroduced into its native host, D. melanogaster, by embryonic microinjection. The cell line-adapted wMelPop strains were characterized by a loss of infectivity when reintroduced into the original host, grew to decreased densities, and had reduced abilities to cause life-shortening infection and cytoplasmic incompatibility compared to the original strain. We interpret these shifts in phenotype as evidence for genetic adaptation to the mosquito intracellular environment. The use of cell lines to preadapt Wolbachia to novel hosts is suggested as a possible strategy to improve the success of transinfection in novel target insect species.
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Affiliation(s)
- Conor J McMeniman
- School of Integrative Biology, The University of Queensland, St. Lucia, Brisbane, QLD 4072, Australia
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Ren X, Hoiczyk E, Rasgon JL. Viral paratransgenesis in the malaria vector Anopheles gambiae. PLoS Pathog 2008; 4:e1000135. [PMID: 18725926 PMCID: PMC2500179 DOI: 10.1371/journal.ppat.1000135] [Citation(s) in RCA: 95] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Accepted: 07/23/2008] [Indexed: 11/19/2022] Open
Abstract
Paratransgenesis, the genetic manipulation of insect symbiotic microorganisms, is being considered as a potential method to control vector-borne diseases such as malaria. The feasibility of paratransgenic malaria control has been hampered by the lack of candidate symbiotic microorganisms for the major vector Anopheles gambiae. In other systems, densonucleosis viruses (DNVs) are attractive agents for viral paratransgenesis because they infect important vector insects, can be genetically manipulated and are transmitted to subsequent generations. However, An. gambiae has been shown to be refractory to DNV dissemination. We discovered, cloned and characterized the first known DNV (AgDNV) capable of infection and dissemination in An. gambiae. We developed a flexible AgDNV-based expression vector to express any gene of interest in An. gambiae using a two-plasmid helper-transducer system. To demonstrate proof-of-concept of the viral paratransgenesis strategy, we used this system to transduce expression of an exogenous gene (enhanced green fluorescent protein; EGFP) in An. gambiae mosquitoes. Wild-type and EGFP-transducing AgDNV virions were highly infectious to An. gambiae larvae, disseminated to and expressed EGFP in epidemiologically relevant adult tissues such as midgut, fat body and ovaries and were transmitted to subsequent mosquito generations. These proof-of-principle data suggest that AgDNV could be used as part of a paratransgenic malaria control strategy by transduction of anti-Plasmodium peptides or insect-specific toxins in Anopheles mosquitoes. AgDNV will also be extremely valuable as an effective and easy-to-use laboratory tool for transient gene expression or RNAi in An. gambiae. Paratransgenesis, the genetic manipulation of mosquito symbiotic microorganisms, is being considered as a potential strategy to control malaria. Microorganisms associated with Anopheles mosquitoes could be manipulated to alter the mosquito's ability to become infected with and transmit the malaria parasites, or reduce mosquito fecundity or lifespan. We identified the first potential microorganism (An. gambiae densovirus; AgDNV) for paratransgenesis of the major malaria vector Anopheles gambiae. AgDNV is highly infectious to An. gambiae larvae, disseminates to adult tissues and is transmitted vertically to subsequent generations. Recombinant AgDNV was able to transduce expression of an exogenous gene (EGFP) in An. gambiae cells and mosquitoes. EGFP-transducing virions infected mosquitoes, expressed EGFP in epidemiologically relevant tissues and were transmitted to offspring in a similar manner to wild-type virus. AgDNV could be used as part of a paratransgenic malaria control strategy by transduction of anti-Plasmodium genes or insect-specific toxins in Anopheles mosquitoes, as well as an easy-to-use system for transient gene expression and RNAi for basic laboratory research.
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Affiliation(s)
- Xiaoxia Ren
- The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, United States of America
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Egbert Hoiczyk
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jason L. Rasgon
- The Johns Hopkins Malaria Research Institute, Baltimore, Maryland, United States of America
- The W. Harry Feinstone Department of Molecular Microbiology and Immunology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
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Sakamoto JM, Azad AF. Propagation of arthropod-borne Rickettsia spp. in two mosquito cell lines. Appl Environ Microbiol 2007; 73:6637-43. [PMID: 17766452 PMCID: PMC2075076 DOI: 10.1128/aem.00923-07] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rickettsiae are obligate intracellular alphaproteobacteria that include pathogenic species in the spotted fever, typhus, and transitional groups. The development of a standardized cell line in which diverse rickettsiae can be grown and compared would be highly advantageous to investigate the differences among and between pathogenic and nonpathogenic species of rickettsiae. Although several rickettsial species have been grown in tick cells, tick cells are more difficult to maintain and they grow more slowly than insect cells. Rickettsia-permissive arthropod cell lines that can be passaged rapidly are highly desirable for studies on arthropod-Rickettsia interactions. We used two cell lines (Aedes albopictus cell line Aa23 and Anopheles gambiae cell line Sua5B) that have not been used previously for the purpose of rickettsial propagation. We optimized the culture conditions to propagate one transitional-group rickettsial species (Rickettsia felis) and two spotted-fever-group rickettsial species (R. montanensis and R. peacockii) in each cell line. Both cell lines allowed the stable propagation of rickettsiae by weekly passaging regimens. Stable infections were confirmed by PCR, restriction digestion of rompA, sequencing, and the direct observation of bacteria by fluorescence in situ hybridization. These cell lines not only supported rickettsial growth but were also permissive toward the most fastidious species of the three, R. peacockii. The permissive nature of these cell lines suggests that they may potentially be used to isolate novel rickettsiae or other intracellular bacteria. Our results have important implications for the in vitro maintenance of uncultured rickettsiae, as well as providing insights into Rickettsia-arthropod interactions.
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Affiliation(s)
- Joyce M Sakamoto
- Department of Microbiology and Immunology, School of Medicine, 660 West Redwood St., Howard Hall, Room 324B, University of Maryland, Baltimore, MD 21201, USA.
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