The lack of antiviral innate immune responses during severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections is characterized by limited production of interferons (IFNs). One protein associated with Aicardi–Goutières syndrome, SAMHD1, has been shown to negatively regulate the IFN-1 signaling pathway. However, it is unclear whether elevated IFN signaling associated with genetic loss of SAMHD1 would affect SARS-CoV-2 replication. In this study, we established in vitro tissue culture model systems for SARS-CoV-2 and human coronavirus OC43 infections in which SAMHD1 protein expression was absent as a result of CRISPR–Cas9 gene KO or lentiviral viral protein X–mediated proteosomal degradation. We show that both SARS-CoV-2 and human coronavirus OC43 replications were suppressed in SAMHD1 KO 293T and differentiated THP-1 macrophage cell lines. Similarly, when SAMHD1 was degraded by virus-like particles in primary monocyte-derived macrophages, we observed lower levels of SARS-CoV-2 RNA. The loss of SAMHD1 in 293T and differentiated THP-1 cells resulted in upregulated gene expression of IFNs and innate immunity signaling proteins from several pathways, with STAT1 mRNA being the most prominently elevated ones. Furthermore, SARS-CoV-2 replication was significantly increased in both SAMHD1 WT and KO cells when expression and phosphorylation of STAT1 were downregulated by JAK inhibitor baricitinib, which over-rode the activated antiviral innate immunity in the KO cells. This further validates baricitinib as a treatment of SARS-CoV-2–infected patients primarily at the postviral clearance stage. Overall, our tissue culture model systems demonstrated that the elevated innate immune response and IFN activation upon genetic loss of SAMHD1 effectively suppresses SARS-CoV-2 replication.
【저자키워드】 SARS-CoV-2, Innate immunity, COVID-19, Coronavirus disease 2019, SARS-CoV-2, Severe acute respiratory syndrome coronavirus 2, ACE2, angiotensin-converting enzyme 2, FBS, fetal bovine serum, MOI, multiplicity of infection, SAMHD1, JAK pathway, Stat1, AGS, Aicardi–Goutières syndrome, ARHGEF5, Rho guanine nucleotide exchange factor 5, cDNA, complementary DNA, DMEM, Dulbecco's modified Eagle's medium, FDA, US Food and Drug Administration, HCoV-OC43, human coronavirus OC43, IFN, interferon, IRF3, IFN regulatory factor 3, ISG, IFN-stimulated gene, JAK, Janus kinase, MDM, monocyte-derived macrophage, NSP, nonstructural protein, pSTAT1, phosphorylated form of STAT1, qRT–PCR, quantitative RT–PCR, SAMHD1, sterile alpha motif and histidine–aspartate domain–containing protein 1, STAT1, signal transducer and activator of transcription 1, VLP, virus-like particle, Vpx, viral protein X, 【초록키워드】 Treatment, Macrophage, Baricitinib, coronavirus, Gene Expression, innate immune response, macrophages, Antiviral, Innate immunity, Genetic, Infection, interferons, interferon, IFN signaling, severe acute respiratory syndrome Coronavirus, Replication, Human coronavirus, Protein, CRISPR, Viral, Culture, cells, mRNA, immune responses, Phosphorylation, IFN, SARS-CoV-2 RNA, signaling pathway, Degradation, SAMHD1, Stat1, human coronavirus OC43, respiratory, virus-like particles, expression, SARS-CoV-2 replication, IFNs, JAK inhibitor, Signaling, cell lines, regulate, Pathways, tissue culture, acute respiratory syndrome, Activation, Viral protein, Virus-like particle, acute respiratory syndrome coronavirus, tissue, acute respiratory syndrome coronavirus 2, interferons (IFNs), syndrome, protein expression, 293T, clearance, Monocyte-derived macrophages, SARS-CoV-2–infected patients, Affect, Cell, THP-1, model system, significantly increased, shown, lack, elevated, characterized, activated, demonstrated, upregulated, suppressed, suppresse, downregulated, lentiviral, SARS-CoV-2–infected patient, 【제목키워드】 Elimination, Protein, cellular, syndrome, suppresse, activate,