ilas-conference-2021 | Page 45

Emma Widlake
School of Life Sciences
In cells defective for the dominant antiviral pathway , the normally redundant piRNA pathway becomes an effective response against the Venezuelan Equine Encephalitis Virus vaccine strain
The RNAi response is a key mosquito antiviral defense that consists of three separate pathways , the siRNA , miRNA and piRNA . Each pathway produces and targets double stranded viral RNA segments of different lengths . TC-83 is a vaccine strain of the mosquito-borne Venezuelan Equine Encephalitis Virus that cannot replicate efficiently in either vertebrate or mosquito cells in vivo . Previous research has shown the siRNA response is a dominant response active against TC-83 in U4.4 cells . In this study , C7 / 10 cells defective in the siRNA response were infected with TC-83 and the cellular RNAs were sent for sequencing . Sequences were then mapped to the TC-83 genome . Sequences that showed common characteristics of viral piRNAs were isolated from infected cells . These included lengths of 25 and 26 nucleotides with A10 bias on the negative strand of TC-83 and that mapped to specific regions of the TC-83 genome . This suggests that when the dominant siRNA pathway is defective , the piRNA pathway acts as a redundant anti-viral surveillance pathway . This research is important as it highlights the need for viral populations to evade multiple immune pathways during infection and ways in which alternative pathways can also play a role in antiviral responses in mosquitoes .
Postgraduate Conference 2021 Page 44