41st Annual Meeting of the Society for Invertebrate Pathology
and 9th International Conference on Bacillus thuringiensis

Comparative genomic studies have highlighted the role of symbiotic associations in biological evolution. However very few of these relationships involve viruses, except the remarkable association of polydnaviruses (PDVs) with tens of thousand species of parasitic wasps that develop within the body of lepidopteran larvae. PDV particles, injected along with parasite eggs into the host body, act by manipulating host immune defences, development and physiology thereby enabling wasp larvae to survive in a potentially harmful environment. The virus is completely dependent on the wasp for particles production that occurs exclusively in specialized cells of the ovaries. Surprisingly, the genome enclosed in the particles encodes almost no viral structural protein but mostly factors used to manipulate the parasitized host. It was thus questioned whether PDVs were true viruses or a genetic secretion somehow created by the wasp. We unravelled recently the viral nature of PDVs associated with braconid wasps by characterizing a large set of virus genes encoding structural components of PDV particles in the braconid species Chelonus inanitus and Cotesia congregata which belong to the most distantly related subfamilies of bracovirus-associated wasps.