Abstract
Many viruses disrupt host gene expression by degrading host mRNAs and/or manipulating translation activities to create a cellular environment favorable for viral replication. Often, virus-induced suppression of host gene expression, including those involved in antiviral responses, contributes to viral pathogenicity. Accordingly, clarifying the mechanisms of virus-induced disruption of host gene expression is important for understanding virus–host cell interactions and virus pathogenesis. Three highly pathogenic human coronaviruses (CoVs), including severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2, have emerged in the past two decades. All of them encode nonstructural protein 1 (nsp1) in their genomes. Nsp1 of SARS-CoV and MERS-CoV exhibit common biological functions for inducing endonucleolytic cleavage of host mRNAs and inhibition of host translation, while viral mRNAs evade the nsp1-induced mRNA cleavage. SARS-CoV nsp1 is a major pathogenic determinant for this virus, supporting the notion that a viral protein that suppresses host gene expression can be a virulence factor, and further suggesting the possibility that SARS-CoV-2 nsp1, which has high amino acid identity with SARS-CoV nsp1, may serve as a major virulence factor. This review summarizes the gene expression suppression functions of nsp1 of CoVs, with a primary focus on SARS-CoV nsp1 and MERS-CoV nsp1.
Highlights
Three highly pathogenic human coronaviruses (HCoVs), including severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2, emerged within the first 20 years of the twenty-first century
IFN-related gene expression, expression of the nsp1s of the α-CoVs markedly downregulates STAT1 phosphorylation at S727 residue without affecting the STAT1 expression levels and STAT1 phosphorylation at S701, and STAT1, ISG15, and IRF9 mRNAs are significantly upregulated in cells infected with a Feline infectious peritonitis virus (FIPV) mutant carrying a deletion of amino acids 91–95 in the nsp1 without severely affecting virus replication ability [77]
Shen et al demonstrated that expression of nsp1 of transmissible gastroenteritis virus (TGEV), porcine respiratory coronavirus (PRCV), swine acute diarrhea syndrome coronavirus (SADS-CoV), Porcine epidemic diarrhea virus (PEDV), HCoV-229E, or HCoV-NL63 reduces IFN-related gene expression, expression of the nsp1s of the α-CoVs markedly downregulates STAT1 phosphorylation at S727 residue without affecting the STAT1 expression levels and STAT1 phosphorylation at S701, and STAT1, ISG15, and IRF9 mRNAs are significantly upregulated in cells infected with a FIPV mutant carrying a deletion of amino acids 91–95 in the nsp1 without severely affecting virus replication ability [77]
Summary
Three highly pathogenic human coronaviruses (HCoVs), including severe acute respiratory syndrome (SARS)-CoV, Middle East respiratory syndrome (MERS)-CoV, and SARS-CoV-2, emerged within the first 20 years of the twenty-first century. All highly pathogenic HCoVs, including SARS-CoV, MERS-CoV, and SARS-CoV-2, belong to the genus β-CoV and are considered to be initially derived from wild mammals, most probably bats [16,17]. They are associated with severe lower respiratory tract infections [18,19,20], while other HCoVs, including HCoV-OC43 and HCoV-HKU1, belonging to the genus β-CoV, and HCoV-229E and HCoV-NL63, belonging to the genus α-CoV, cause relatively mild upper respiratory tract infections [21,22].
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