title: Symbionts commonly provide broad spectrum resistance to viruses in insects: a comparative analysis of Wolbachia strains.
abstract: In the last decade, bacterial symbionts have been shown to play an important role in protecting hosts against pathogens. Wolbachia, a widespread symbiont in arthropods, can protect Drosophila and mosquito species against viral infections. We have investigated antiviral protection in 19 Wolbachia strains originating from 16 Drosophila species after transfer into the same genotype of Drosophila simulans. We found that approximately half of the strains protected against two RNA viruses. Given that 40% of terrestrial arthropod species are estimated to harbour Wolbachia, as many as a fifth of all arthropods species may benefit from Wolbachia-mediated protection. The level of protection against two distantly related RNA viruses--DCV and FHV--was strongly genetically correlated, which suggests that there is a single mechanism of protection with broad specificity. Furthermore, Wolbachia is making flies resistant to viruses, as increases in survival can be largely explained by reductions in viral titer. Variation in the level of antiviral protection provided by different Wolbachia strains is strongly genetically correlated to the density of the bacteria strains in host tissues. We found no support for two previously proposed mechanisms of Wolbachia-mediated protection--activation of the immune system and upregulation of the methyltransferase Dnmt2. The large variation in Wolbachia's antiviral properties highlights the need to carefully select Wolbachia strains introduced into mosquito populations to prevent the transmission of arboviruses.
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Julien
authors.initials: J
authors.lastname: Martinez
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Ben
authors.initials: B
authors.lastname: Longdon
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Simone
authors.initials: S
authors.lastname: Bauer
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Yuk-Sang
authors.initials: YS
authors.lastname: Chan
authors.affiliation: Laboratories of Genome Dynamics, Department Cell and Developmental Biology, Center of Anatomy and Cell Biology, Medical University of Vienna, Vienna, Austria.
authors.forename: Wolfgang J
authors.initials: WJ
authors.lastname: Miller
authors.affiliation: Department of Environmental and Natural Resources Management, University of Patras, Agrinio, Greece; Biomedical Sciences Research Center "Alexander Fleming", Vari, Greece; Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria.
authors.forename: Kostas
authors.initials: K
authors.lastname: Bourtzis
authors.affiliation: Instituto Gulbenkian de Ciência, Oeiras, Portugal.
authors.forename: Luis
authors.initials: L
authors.lastname: Teixeira
authors.affiliation: Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Francis M
authors.initials: FM
authors.lastname: Jiggins
mesh_terms: D000818:Animals; D004330:Drosophila / Q000254:growth & development* / Q000276:immunology* / Q000382:microbiology / Q000821:virology; D005260:Female; D054884:Host-Pathogen Interactions / Q000276:immunology*; D007304:Insect Viruses / Q000472:pathogenicity*; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D013559:Symbiosis / Q000276:immunology*; D014777:Virus Diseases / Q000276:immunology* / Q000382:microbiology / Q000821:virology; D020577:Wolbachia / Q000145:classification / Q000502:physiology*