Viral and host determinants of cell entry of emerging and neglected enveloped viruses

Abstract

Emerging and neglected RNA viruses present a global threat to human, animal, and plant health. Enveloped RNA viruses, which comprise the largest group of emerging infectious agents, are some of the most impactful pathogens in human history and include alpha-, arena-, bunya-, corona-, flavi-, filo-, orthomyxo-, paramyxo-, pox-, retro-, and rhabdo- viruses. Enveloped viruses initiate infection by utilizing one or more viral envelope proteins to attach to host factors on the cell surface and, in response to cellular cues that trigger conformational changes in the envelope protein(s), catalyze fusion between viral and host membranes. Envelope proteins are major targets of the immune system, which produces antibodies against these proteins to curtail infection. Defining basic biology of viral envelope proteins informs vaccine and therapeutic design. Here, we study the viral and host determinants of cell entry of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), thogotoviruses, and lyssaviruses. Using a vesicular stomatitis virus (VSV) reverse genetics platform, we have generated reduced-biocontainment, replication- competent viruses expressing heterologous viral envelope proteins to study basic biology and to serve as vaccines. We have generated a VSV expressing the SARS-CoV-2 spike (S), demonstrated that it recapitulates the S-mediated biology of a SARS-CoV-2 clinical isolate, and showed that it is immunogenic and protects mice from virus challenge. We have also generated VSVs expressing the envelope proteins of thogotoviruses and lyssaviruses, and using CRISPR- Cas9 screening, identified glucosylceramide synthase and low-density lipoprotein receptor family members as host entry factors, respectively. These findings have expanded access to the coronavirus field, owing to our reduced-biocontainment tool, defined a targetable thogotovirus host entry factor, and characterized novel host factors for rabies-causing lyssaviruses.