Selection and Characterization of Rupintrivir-Resistant Norwalk Virus Replicon Cells In Vitro

Antimicrob Agents Chemother. 2018 Apr 26;62(5):e00201-18. doi: 10.1128/AAC.00201-18. Print 2018 May.


Human norovirus (HuNoV) is a major cause of nonbacterial gastroenteritis worldwide, yet despite its impact on society, vaccines and antivirals are currently lacking. A HuNoV replicon system has been widely applied to the evaluation of antiviral compounds and has thus accelerated the process of drug discovery against HuNoV infection. Rupintrivir, an irreversible inhibitor of the human rhinovirus 3C protease, has been reported to inhibit the replication of the Norwalk virus replicon via the inhibition of the norovirus protease. Here we report, for the first time, the generation of rupintrivir-resistant human Norwalk virus replicon cells in vitro Sequence analysis revealed that these replicon cells contained amino acid substitutions of alanine 105 to valine (A105V) and isoleucine 109 to valine (I109V) in the viral protease NS6. The application of a cell-based fluorescence resonance energy transfer (FRET) assay for protease activity demonstrated that these substitutions were involved in the enhanced resistance to rupintrivir. Furthermore, we validated the effect of these mutations using reverse genetics in murine norovirus (MNV), demonstrating that a recombinant MNV strain with a single I109V substitution in the protease also showed reduced susceptibility to rupintrivir. In summary, using a combination of different approaches, we have demonstrated that, under the correct conditions, mutations in the norovirus protease that lead to the generation of resistant mutants can rapidly occur.

Keywords: antiviral agents; drug resistance mechanisms; noroviruses; protease inhibitors; proteases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Antiviral Agents / pharmacology*
  • Cell Line, Tumor
  • Cysteine Endopeptidases / genetics
  • Cysteine Endopeptidases / metabolism
  • Fluorescence Resonance Energy Transfer
  • Humans
  • Isoxazoles / pharmacology*
  • Mutation
  • Norwalk virus / drug effects*
  • Norwalk virus / genetics
  • Pyrrolidinones / pharmacology*
  • Viral Proteins / genetics
  • Viral Proteins / metabolism
  • Virus Replication / drug effects
  • Virus Replication / genetics


  • Antiviral Agents
  • Isoxazoles
  • Pyrrolidinones
  • Viral Proteins
  • Cysteine Endopeptidases
  • 3C proteases
  • rupintrivir