Natural monobacterial environments modulate viral infection in Caenorhabditis elegans

The microbes associated with an organism play a pivotal role in modulating their host susceptibility to viral infections. However, the influence of individual microbes on viral infections is not well understood. Here, we examined the impact of 67 naturally bacterial associates on Caenorhabditis elegans susceptibility to Orsay virus. Our findings reveal that viral infection of C. elegans is significantly influenced by monobacterial environments. The majority of tested natural bacterial environments reduced C. elegans viral infection while some increased susceptibility compared to an Escherichia coli environmental reference. The reduction in viral infection is not caused by degradation of the virions or poor nutrition of C. elegans by the bacteria. The reduction in viral infection does not require known antiviral responses, including RNA interference and transcriptional regulation downstream of the RIG-I homolog DRH-1. However, one bacterium, Lelliottia JUb276, reduced susceptibility but does not induce resistance to viral infection in drh-1 mutants. Our research underscores the importance of considering the natural biotic environment in studies of viral infections and provides insights for future research on host-microbes-virus interactions and viral immunity. AUTHOR CONTRIBUTIONSConceptualization: RG, MAF; Formal analysis: RG; Investigation: RG; Resources: MAF; Data Curation: RG; Writing - Original Draft: RG, MAF; Writing - Review & Editing: RG, MAF; Visualization: RG; Supervision: MAF; Project administration: RG, MAF; Funding acquisition: RG, MAF.