Antiviral research
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SARS-CoV-2-caused COVID-19 cases are growing globally, calling for developing effective therapeutics to control the current pandemic. SARS-CoV-2 and SARS-CoV recognize angiotensin-converting enzyme 2 (ACE2) receptor via the receptor-binding domain (RBD). ⋯ The 18F3-recognizing epitopes on RBD did not overlap with the ACE2-binding sites, whereas those recognized by 7B11 were close to the ACE2-binding sites, explaining why 7B11 could, but 18F3 could not, block SARS-CoV or SARS-CoV-2 RBD binding to ACE2 receptor. Our study provides an alternative approach to prevent SARS-CoV-2 infection using anti-SARS-CoV nAbs.
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There is an urgent need to identify antivirals to curtail the COVID-19 pandemic. Herein, we report the sensitivity of SARS-CoV-2 to recombinant human interferons α and β (IFNα/β). ⋯ These results suggest that SARS-CoV-2 is more sensitive than many other human pathogenic viruses, including SARS-CoV. Overall, our results demonstrate the potential efficacy of human Type I IFN in suppressing SARS-CoV-2 infection, a finding which could inform future treatment options for COVID-19.
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Baloxavir marboxil (BXM) is a potent inhibitor of the polymerase acidic (PA) protein of influenza viruses. However, clinical trials predominantly involving influenza A(H1N1) and A(H3N2) infections showed that BXM exhibited a low barrier of resistance. Contrasting with influenza A viruses, BXM-resistant influenza B variants remain poorly documented. ⋯ Peak viral titers were comparable for the WT, I38T and I38M recombinants (7.95 ± 0.5, 7.45 ± 0.25 and 8.11 ± 0.28 logTCID50/mL), respectively, whereas it was significantly lower for the E23K mutant (6.28 ± 0.28 logTCID50/mL;P < 0.05 vs the WT). In mice, the WT, I38T and I38M recombinants induced mortality rates of 60%, 40% and 100%, respectively and similar lung viral titers were obtained for the three groups at days 3 and 6 p.i. In conclusion, the fitness of BXA-resistant I38T and I38M PA mutants appears unaltered in contemporary influenza B viruses warranting surveillance for their emergence.