Dominique Daniels, Wilfrid Laurier University

Dominique E. Daniels1, Akarin Asavajaru2, Jonathan M. Wilson1, Arinjay Banerjee2, Stephanie J. DeWitte-Orr1,3. 1. Department of Biology, Wilfrid Laurier University, Waterloo, ON 2. Vaccine and Infectious Disease Organization (VIDO), University of Saskatchewan, Saskatoon, SK 3. Department of Health Sciences, Wilfrid Laurier University, Waterloo, ON

Fighting & Responding

Viruses produce long dsRNA (LdsRNA) during replication, which stimulates the type 1 interferon (IFN) response in a sequence-independent manner, leading to the production of IFN stimulated genes (ISGs) which work to stop viral replication. Recent in vitro evidence has shown that at LdsRNA doses lower than needed to stimulate the IFN response an antiviral RNA interference (dsRNAi) is also active in vertebrates. dsRNAi is a sequence-dependent response where LdsRNA is cleaved into siRNAs that RISC uses to bind and sequester or degrade complementary viral mRNA. We aimed to determine if intranasal delivery of low dose LdsRNA could stimulate the dsRNAi response against SARS-CoV2 in vivo. Low dose SARS-CoV2 N gene or MCherry (sequence mismatch control) LdsRNA sequences were administered intranasally to Syrian hamsters and animals were infected with SARS-CoV2 (10^5 TCID50/mL) one day post-treatment. LdsRNA delivery to the lungs was confirmed via immunohistochemistry at 2 dpi (SARS-CoV2 spike and Mx1 (an ISG) protein presence during the infection is currently being quantified). SARS-CoV2 spike transcripts were undetectable by RT-qPCR in the lungs of LdsRNA-treated animals (2, 4, 7 dpi), however only slight upregulation of ISG15 expression occurred in the lung, with less upregulation in the N LdsRNA-treated animals compared to mCherry. The protection provided by both LdsRNA sequences, but lower ISG induction by the viral specific sequence, suggests that low dose LdsRNA may have stimulated both IFN and dsRNAi, representing a novel perspective on innate antiviral immunity in mammals.