SARS-CoV-2 Uses Nonstructural Protein 16 To Evade Restriction by IFIT1 and IFIT3

Craig Schindewolf, Kumari Lokugamage, Michelle N. Vu, Bryan A. Johnson, Dionna Scharton, Jessica A. Plante, Birte Kalveram, Patricia A. Crocquet-Valdes, Stephanea Sotcheff, Elizabeth Jaworski, Rojelio E. Alvarado, Kari Debbink, Matthew D. Daugherty, Scott C. Weaver, Andrew L. Routh, David H. Walker, Kenneth S. Plante, Vineet D. Menachery

Research output: Contribution to journalArticlepeer-review

Abstract

Understanding the molecular basis of innate immune evasion by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an important consideration for designing the next wave of therapeutics. Here, we investigate the role of the nonstructural protein 16 (NSP16) of SARS-CoV-2 in infection and pathogenesis. NSP16, a ribonucleoside 29-O-methyltransferase (MTase), catalyzes the transfer of a methyl group to mRNA as part of the capping process. Based on observations with other CoVs, we hypothesized that NSP16 29-O-MTase function protects SARS-CoV-2 from cap-sensing host restriction. Therefore, we engineered SARS-CoV-2 with a mutation that disrupts a conserved residue in the active site of NSP16. We subsequently show that this mutant is attenuated both in vitro and in vivo, using a hamster model of SARS-CoV-2 infection. Mechanistically, we confirm that the NSP16 mutant is more sensitive than wild-type SARS-CoV-2 to type I interferon (IFN-I) in vitro. Furthermore, silencing IFIT1 or IFIT3, IFN-stimulated genes that sense a lack of 29-O-methylation, partially restores fitness to the NSP16 mutant. Finally, we demonstrate that sinefungin, an MTase inhibitor that binds the catalytic site of NSP16, sensitizes wild-type SARS-CoV-2 to IFN-I treatment and attenuates viral replication. Overall, our findings highlight the importance of SARS-CoV-2 NSP16 in evading host innate immunity and suggest a target for future antiviral therapies.

Original languageEnglish (US)
JournalJournal of virology
Volume97
Issue number2
DOIs
StatePublished - Feb 2023

Keywords

  • 2'-O-methyltransferase
  • IFIT1
  • IFIT3
  • NSP16
  • SARS-CoV-2
  • antiviral agents
  • coronavirus
  • interferon-stimulated gene

ASJC Scopus subject areas

  • Insect Science
  • Virology
  • Microbiology
  • Immunology

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