Activity and inhibition of the SARS-CoV-2 Omicron nsp13 R392C variant using RNA duplex unwinding assays.

SLAS Discov

Department of Microbiology-Immunology, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 USA; Department of Medicine, Division of Infectious Diseases, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 USA; Center for Pathogen Genomics and Microbial Evolution, Havey Institute for Global Health, Northwestern University Feinberg School of Medicine, Chicago, IL 60611 USA. Electronic address:

Published: April 2024

SARS-CoV-2 nsp13 helicase is an essential enzyme for viral replication and a promising target for antiviral drug development. This study compares the double-stranded RNA (dsRNA) unwinding activity of nsp13 and the Omicron nsp13 variant, which is predominant in currently circulating lineages. Using in vitro gel- and fluorescence-based assays, we found that both nsp13 and nsp13 have dsRNA unwinding activity with equivalent kinetics. Furthermore, the R392C mutation had no effect on the efficiency of the nsp13-specific helicase inhibitor SSYA10-001. We additionally confirmed the activity of several other helicase inhibitors against nsp13, including punicalagin that inhibited dsRNA unwinding at nanomolar concentrations. Overall, this study reveals the utility of using dsRNA unwinding assays to screen small molecules for antiviral activity against nsp13 and the Omicron nsp13 variant. Continual monitoring of newly emergent variants will be essential for considering resistance profiles of lead compounds as they are advanced towards next-generation therapeutic development.

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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC11160173PMC
http://dx.doi.org/10.1016/j.slasd.2024.01.006DOI Listing

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