Host-Bacteria-Virus Interactions in Caenorhabditis elegans

Abstract

The factors governing transmissibility of viruses between susceptible hosts are not well understood. The discovery of Orsay virus and the experimental tractability of the C. elegans host enables the study of the determinants of virus transmission. Studies from mice and insects have demonstrated that bacteria influence viral infection and transmission. Here we used Caenorhabditis elegans and Orsay virus to screen a panel of bacteria to study their impact on virus transmission rates. We identified that exposure to and ingestion of these bacteria result in divergent bacteria-specific effects on transmission rate. Specifically, we observed that the presence of Pseudomonas aeruginosa and Pseudomonas lurida reduced transmission and infection rates relative to the standard laboratory diet of Escherichia coli OP50, whereas the presence and ingestion of Ochrobactrum species enhanced infection by Orsay virus. We observed that the inhibitory effect of P. aeruginosa and P. lurida was dependent on quorum- sensing pathways and the two-component response regulator gacA. We noted that Ochrobactrum ingestion into the intestinal lumen was important for its ability to enhance Orsay infection. Our data suggest there is a tripartite interaction between the Orsay virus, bacteria, and the C. elegans host that can strongly modulate virus transmission in a bacterial species-specific manner.