Utilizing comparative transcriptomics to understand the effects of vesicular stomatitis virus infection on neuro-sensory function in Culicoides midges

Culicoides midges are important vectors of many livestock pathogens, including orbiviruses and rhabdoviruses. These viruses heavily infect the insect’s eyes and other sensory organs as infection disseminates. Previous midge infection studies with the orbivirus epizootic hemorrhagic disease virus (EHDV) have shown that many genes associated with vision, memory and other behaviors were downregulated, while a few genes associated with olfaction were upregulated. Because vision is important for midges to navigate their environment and is key for vector surveillance via light trapping, virus alteration of these traits has significant implications on host seeking and disease risk assessment. We hypothesized that the reported effects of orbivirus infection on gene expression in midges would also be observed in rhabdovirus-infected midges. In this study, we used RNAseq to determine differential expression (DE) of genes in female Culicoides sonorensis infected with the rhabdoviral livestock pathogen, vesicular stomatitis virus (VSV). Midges were fed either blood meals spiked with media containing VSV or virus-free media (controls) and were collected 3 days and 8 days post-ingestion. RNA was then extracted from each replicate (N=18) in pools of 25 midges. RNA was sequenced, and a updated de novo transcriptome was assembled utilizing prior transcriptomic data. Gene ontology enrichment, KEGG pathway assignment, and quantitative comparisons were used to identify DE transcripts (FDR > 0.05) in VSV infected midges. This approach allows us to explore and understand how virus infection affects the midge at a transcriptomic level, which can provide valuable insight into altered visual perception for future behavioral phenotypic studies.