Char, A. B. | bioRxiv Science

bioRxiv2024

Antiviral insulin signaling during West Nile virus infection results in viral mutations

Arthropod-borne viruses or arboviruses, including West Nile virus (WNV), dengue virus (DENV), and Zika virus (ZIKV) pose significant threats to public health. It is imperative to develop novel methods to control these mosquito-borne viral infections. We previously showed that insulin/insulin-like growth factor-1 signaling (IIS)-dependent activation of ERK and JAK-STAT signaling has significant antiviral activity. Continuous immune pressure can lead to adaptive mutations of viruses during infection. We aim to elucidate how IIS-signaling in mosquitoes selects for West Nile virus escape variants, to help formulate future transmission blocking strategies. We hypothesize that passage of WNV under activation of IIS will induce adaptive mutations or escape variants in the infecting virus. To test our hypothesis, WNV was serially passaged through Culex quinquefasciatus Hsu cells in the presence or absence of bovine insulin to activate IIS antiviral pressure. We sequenced WNV genes encoding for E, NS2B, NS3, and NS5 and identified variants in E and NS5 arising from IIS antiviral pressure. In parallel to the genetic analyses, we also report differences in the levels of virus replication and Akt activation in human cells using virus passaged in the presence or absence of insulin. Finally, using adult Culex quinquefasciatus, we demonstrated the enhancement of immune response gene expression in virus-infected mosquitoes fed on insulin, compared to control. Notably, virus collected from insulin-fed mosquitoes contained a non-synonymous mutation in NS3. These results contribute towards achieving our long-term goal of manipulating mosquito IIS-dependent antiviral immunity to reduce WNV or other flavivirus transmission to mammalian hosts.

immunology↗

bioRxiv2023

Insulin-mediated endothelin signaling is antiviral during West Nile virus infection

West Nile virus (WNV) is the most prevalent mosquito-borne virus in the United States with approximately 2,000 cases each year. There are currently no approved human vaccines and a lack of prophylactic and therapeutic treatments. Understanding host responses to infection may reveal potential intervention targets to reduce virus replication and disease progression. The use of Drosophila melanogaster as a model organism to understand innate immunity and host antiviral responses is well established. Previous studies revealed that insulin-mediated signaling regulates WNV infection in invertebrates by regulating canonical antiviral pathways. Because insulin signaling is well-conserved across insect and mammalian species, we sought to determine if results using D. melanogaster can be extrapolated for the analysis of orthologous pathways in humans. Here, we identify insulin-mediated endothelin signaling using the D. melanogaster model and evaluate an orthologous pathway in human cells during WNV infection. We demonstrate that endothelin signaling reduces WNV replication through the activation of canonical antiviral signaling. Taken together, our findings show that endothelin-mediated antiviral immunity is broadly conserved across species and reduces replication of viruses that can cause severe human disease. IMPORTANCEArboviruses, particularly those transmitted by mosquitoes, pose a significant threat to humans and are an increasing concern because of climate change, human activity, and expanding vector-competent populations. West Nile virus is of significant concern as the most frequent mosquito-borne disease transmitted annually within the continental United States. Here, we identify a previously uncharacterized signaling pathway that impacts West Nile virus infection, namely endothelin signaling. Additionally, we demonstrate that we can successfully translate results obtained from D. melanogaster into the more relevant human system. Our results add to the growing field of insulin-mediated antiviral immunity and identifies potential biomarkers or intervention targets to better address West Nile virus infection and severe disease.

microbiology↗