Published on December 14, 2018 | Updated on December 14, 2018

ComEndoVir Project

Interaction between commensal and endosymbiotic bacteria and their impact on viral infection in insects

Co-leaders: Natacha Kremer (LBBE) & François Leulier (IGFL)

The ComEndoVir project aims to decipher the interaction between commensal and endosymbiotic bacterial communities in insects, and how this interaction shapes host physiology and resistance to viral infection. This challenges the classic bipartite vision of host-parasite interactions by considering hosts as holobionts, i.e. individuals associated to and interacting with a variety of symbiotic microorganisms referred to as the microbiota.
Multipartite interactions occur between the host and its symbionts as well as between microbial symbiotic communities, but the impact on host phenotype is still poorly understood. In mammals, intestinal bacteria modulate host development, physiology and response to viral infection. This also occurs in insects where gut commensal bacteria are major modulators of host development and physiology, notably at the larval stage. Insect bacterial symbionts also mediate antiviral protection. Indeed, both gut commensal bacteria and the non-obligate endosymbiont Wolbachia can interfere with viral infection. Wolbachia can also interact with the native microbiota, influencing the load and transmission of other bacterial symbionts in arthropods. However, the impact of Wolbachia on gut bacteria diversity in the field is still unknown. Moreover, the impact of the interaction between endosymbiotic and commensal bacteria on viral infection has never been explored.
Bacterial community profiling will be used to determine the composition and the density of the gut bacterial flora in wild Drosophila isolated from different food substrates. We hypothesized that fly gut microbiome composition will differ according to Wolbachia infection status and/or nutritive substrate. The impact of the interaction between Wolbachia and gut bacterial species on viral infection will further be evaluated. Current knowledge suggests that Wolbachia-mediated virus blocking in insects occurs through the modulation of host metabolism. Lactobacillus plantarum, a gut commensal bacterium from Drosophila, is a major modulator of host metabolism at the juvenile stage and recapitulates on its own the growth promoting effect of the conventional Drosophila gut bacterial flora. We suspect that the interaction between Wolbachia and gut bacterial species like L. plantarum could influence host physiology, and likely impact the outcome of viral infection. Therefore, host life-history traits, viral and bacterial load will be monitored between axenic and gnotobiotic individuals, i.e. monoassociated to L. plantarum or harbouring a conventional gut bacterial flora. This will be conducted in Drosophila with a Wolbachia-infected or Wolbachia-free background, after oral exposure to Drosophila C virus or a mock infection. Drosophila genes involved in this multipartite interaction will be identified using RNA-Sequencing and confirmed by in vivo functional assay.
This multidisciplinary project could highlight the ecological influence of vertically transmitted endosymbionts on environmentally acquired gut bacterial flora, unravel the consequences of the interaction between different symbiotic bacterial communities on host physiology, development and resistance to viral infection, but also improve the implementation of antiviral strategies.

: Natacha Kremer, team "Génétique et Evolution des Interactions hôte-parasite" (LBBE) & François Leulier, team "Génomique Fonctionnelle des interactions hôte/bactéries intestinales" (IGFL).
Project duration :
2 years
Financing :
Post-doctoral felowship & consumable money
Postdoctoral fellow :
Vincent Raquin