SARS-CoV-2 viral proteins NSP1 and NSP13 inhibit interferon activation through distinct mechanisms

PLoS One. 2021 Jun 24;16(6):e0253089. doi: 10.1371/journal.pone.0253089. eCollection 2021.

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused a devastating global pandemic, infecting over 43 million people and claiming over 1 million lives, with these numbers increasing daily. Therefore, there is urgent need to understand the molecular mechanisms governing SARS-CoV-2 pathogenesis, immune evasion, and disease progression. Here, we show that SARS-CoV-2 can block IRF3 and NF-κB activation early during virus infection. We also identify that the SARS-CoV-2 viral proteins NSP1 and NSP13 can block interferon activation via distinct mechanisms. NSP1 antagonizes interferon signaling by suppressing host mRNA translation, while NSP13 downregulates interferon and NF-κB promoter signaling by limiting TBK1 and IRF3 activation, as phospho-TBK1 and phospho-IRF3 protein levels are reduced with increasing levels of NSP13 protein expression. NSP13 can also reduce NF-κB activation by both limiting NF-κB phosphorylation and nuclear translocation. Last, we also show that NSP13 binds to TBK1 and downregulates IFIT1 protein expression. Collectively, these data illustrate that SARS-CoV-2 bypasses multiple innate immune activation pathways through distinct mechanisms.

MeSH terms

  • Active Transport, Cell Nucleus / genetics
  • Active Transport, Cell Nucleus / immunology
  • Adaptor Proteins, Signal Transducing / genetics
  • Adaptor Proteins, Signal Transducing / immunology*
  • COVID-19 / genetics
  • COVID-19 / immunology*
  • Cell Nucleus / genetics
  • Cell Nucleus / immunology*
  • HeLa Cells
  • Humans
  • Interferon Regulatory Factor-3 / genetics
  • Interferon Regulatory Factor-3 / immunology*
  • NF-kappa B / genetics
  • NF-kappa B / immunology
  • Phosphorylation / genetics
  • Phosphorylation / immunology
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / immunology
  • RNA-Binding Proteins / genetics
  • RNA-Binding Proteins / immunology*
  • SARS-CoV-2 / genetics
  • SARS-CoV-2 / immunology*
  • Signal Transduction / genetics
  • Signal Transduction / immunology*
  • Viral Nonstructural Proteins / genetics
  • Viral Nonstructural Proteins / immunology*

Substances

  • Adaptor Proteins, Signal Transducing
  • IFIT1 protein, human
  • IRF3 protein, human
  • Interferon Regulatory Factor-3
  • NF-kappa B
  • NSP1 protein, SARS-CoV-2
  • RNA-Binding Proteins
  • Viral Nonstructural Proteins
  • Protein Serine-Threonine Kinases
  • TBK1 protein, human