Investigation of candidate genes for a potential role in Drosophila’s response to the symbiont Wolbachia.

Abstract

Drosophila melanogaster lacks adaptive immunity and only possesses innate immune responses to fight pathogens, which makes it a good model to study innate immunity independently of adaptive immunity responses. Interestingly, innate immunity reactions in Drosophila share similar evolutionary roots with those of humans, and studies of the symbiotic flora both in insects and in mammals have shown that these symbionts affect host immunity. Wolbachia is a maternally transmitted obligate intracellular symbiont, estimated to be present in approximately 50percent of all insect species. It is naturally found in Drosophila melanogaster and although it does not induce an immune response, it has been found to confer its host an increased resistance against certain pathogens. However, when introduced into a novel host, Aedes aegypti, a strain of Wolbachia (wMelPop) led to an upregulation of the expression of genes related to the immunity and protected the mosquitoes against other infections. The relationship between insect hosts and the Wolbachia they harbor remains poorly characterized. We propose to study Wolbachia -Drosophila interactions in an attempt to determine which signaling pathways are involved in controlling Wolbachia. We will analyze the effects of Wolbachia on host immunity and reproduction by examining local immune responses, ovary size and egg production. In parallel, we will follow an in vivo RNAi approach to analyze the effects of selected candidate genes of unknown function in the control of Wolbachia and in flies’ immunity to pathogens. The results of this project are expected to provide information on Wolbachia natural host interactions. A long-term application of this study would be to use Wolbachia as an alternative pest control method.