Host cellular RNA helicases regulate SARS-CoV-2 infection
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has largest RNA genome of approximately 30kb among RNA viruses. The DDX DEAD-box RNA helicase is a multifunctional protein involved in all aspects of RNA metabolism. Therefore, host RNA helicases may regulate and maintain such large viral RNA genome. In this study, I investigated the potential role of several host cellular RNA helicases in SARS-CoV-2 infection. Notably, DDX21 knockdown markedly accumulated intracellular viral RNA and viral production, as well as viral infectivity of SARS-CoV-2, indicating that DDX21 strongly restricts the SARS-CoV-2 infection. As well, MOV10 RNA helicase also suppressed the SARS-CoV-2 infection. In contrast, DDX1, DDX5, and DDX6 RNA helicases were required for SARS-CoV-2 replication. Indeed, SARS-CoV-2 infection dispersed the P-body formation of DDX6 and MOV10 RNA helicases as well as XRN1 exonuclease, while the viral infection did not induce stress granule formation. Accordingly, the SARS-CoV-2 nucleocapsid (N) protein interacted with DDX6, DDX21, and MOV10 and disrupted the P-body formation, suggesting that SARS-CoV-2 N hijacks DDX6 to utilize own viral replication and overcomes their anti-viral effect of DDX21 and MOV10 through as interaction with host cellular RNA helicase. Altogether, host cellular RNA helicases seem to regulate the SARS-CoV-2 infection. ImportanceSARS-CoV-2 has large RNA genome of approximately 30kb. To regulate and maintain such large viral RNA genome, host RNA helicases may involve in SARS-CoV-2 replication. In this study, I have demonstrated that DDX21 and MOV10 RNA helicases limit viral infection and replication. In contrast, DDX1, DDX5 and DDX6 are required for the SARS-CoV-2 infection. Interestingly, the SARS-CoV-2 infection disrupted P-body formation and attenuated or suppressed stress granule formation. Thus, SARS-CoV-2 seems to hijack host cellular RNA helicases to play a proviral role by facilitating viral infection and replication and, by suppressing host innate immune system.