Abstract: The Journal of Infectious Diseases
Brief Report
β-d-N4-hydroxycytidine Inhibits SARSCoV-2 Through Lethal Mutagenesis But
Is Also Mutagenic To Mammalian Cells
Shuntai Zhou,1, Collin S. Hill,1 Sanjay Sarkar,2 Longping V. Tse,3
Blaide M. D. Woodburn,1,4 Raymond F. Schinazi,5 Timothy P. Sheahan,3
Ralph S. Baric,3,6 Mark T. Heise,2,6 and Ronald Swanstrom1,7
Mutagenic ribonucleosides can act as broad-based antiviral
agents. They are metabolized to the active ribonucleoside triphosphate form and concentrate in genomes of RNA viruses
during viral replication. β-d-N4-hydroxycytidine (NHC, initial metabolite of molnupiravir) is >100-fold more active than
ribavirin or favipiravir against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with antiviral activity
correlated to the level of mutagenesis in virion RNA. However,
NHC also displays host mutational activity in an animal cell
culture assay, consistent with RNA and DNA precursors sharing
a common intermediate of a ribonucleoside diphosphate. These
results indicate highly active mutagenic ribonucleosides may
hold risk for the host.
Keywords.
molnupiravir;
mutagenicity;
NHC;
SARS-CoV-2.
Emerging RNA viruses arising from highly heterogeneous
pools of precursor strains are responsible for most recent epidemic and pandemic disease outbreaks in the late 20th and early
21st century. Broad direct-acting antiviral agents represent the
most specific way of treating a viral infection, although these
are often specific to a group of closely related viruses. Besides
remdesivir, which blocks the replication of several coronaviruses, limited therapeutic options are available for treating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)
infections [1]. β-d-N4-hydroxycytidine (NHC, or to designate
Received 18 February 2021; editorial decision 1 May 2021; accepted 4 May 2021; published
online May 7, 2021.
Correspondence: Ronald Swanstrom, PhD, Room 22-006, Lineberger Comprehensive Cancer
Center, University of North Carolina at Chapel Hill, Chapel Hill, NC, 27599 (risunc@med.unc.
edu).
The Journal of Infectious Diseases® 2021;224:415–9
© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society
of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.
DOI: 10.1093/infdis/jiab247
METHODS
We measured SARS-CoV-2 antiviral activity in the presence
of a panel of compounds (rNHC, RBV, and FAV) using the
A549-hACE2 cell model [9, 10]. Sequence analysis to detect the
mutation load was done using the previously published multiplex Primer ID approach to sequence several regions of the
BRIEF REPORT • jid 2021:224 (1 August) • 415
1
Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel
Hill, North Carolina, USA, 2Department of Genetics, University of North Carolina at Chapel
Hill, Chapel Hill, North Carolina, USA, 3Department of Epidemiology, University of North
Carolina at Chapel Hill, Chapel Hill, North Carolina, USA, 4Department of Pharmacology,
University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA, 5Laboratory of
Biochemical Pharmacology, Department of Pediatrics, Emory University School of Medicine
and Children’s Healthcare of Atlanta, Atlanta, Georgia, USA, 6Department of Microbiology
and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North..
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'abstract': '<jats:title>Abstract</jats:title><jats:p>Mutagenic ribonucleosides can act as broad-based '
'antiviral agents. They are metabolized to the active ribonucleoside triphosphate form and '
'concentrate in genomes of RNA viruses during viral replication. β-d-N4-hydroxycytidine (NHC, '
'initial metabolite of molnupiravir) is &gt;100-fold more active than ribavirin or '
'favipiravir against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with '
'antiviral activity correlated to the level of mutagenesis in virion RNA. However, NHC also '
'displays host mutational activity in an animal cell culture assay, consistent with RNA and '
'DNA precursors sharing a common intermediate of a ribonucleoside diphosphate. These results '
'indicate highly active mutagenic ribonucleosides may hold risk for the host.</jats:p>',
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