Abstract

In the last decade, bacterial symbionts have been shown to play an important role in protecting their hosts against natural enemies. Wolbachia, a widespread symbiont in arthropods, has been shown to protect several Drosophila and mosquito species against viral infections and is therefore a potential tool to prevent the transmission of vectored diseases such as Dengue. However, the mechanisms of protection remain unclear and the distribution of the ability to protect among Wolbachia strains has been poorly investigated. I will present our latest results showing that approximately half of Wolbachia strains are able to reduce virus-induced mortality, mainly by limiting the accumulation of viruses within the insect. Antiviral protection also has a broad specificity since it acts against very distantly related viruses. Overall, our results suggest that a substantial proportion of insects may benefit from such a symbiont-mediated immunity which could have major consequences on insect evolution. However, in some cases, protection comes with some costs on the insect fitness which may constraint the evolution of protection in nature but also decrease the success of applications aiming at introducing Wolbachia into mosquito populations.