Viruses (Sep 2021)

A Bioluminescent 3CL<sup>Pro</sup> Activity Assay to Monitor SARS-CoV-2 Replication and Identify Inhibitors

  • Cyrille Mathieu,
  • Franck Touret,
  • Clémence Jacquemin,
  • Yves L. Janin,
  • Antoine Nougairède,
  • Manon Brailly,
  • Magalie Mazelier,
  • Didier Décimo,
  • Virginie Vasseur,
  • Aymeric Hans,
  • José-Carlos Valle-Casuso,
  • Xavier de Lamballerie,
  • Branka Horvat,
  • Patrice André,
  • Mustapha Si-Tahar,
  • Vincent Lotteau,
  • Pierre-Olivier Vidalain

DOI
https://doi.org/10.3390/v13091814
Journal volume & issue
Vol. 13, no. 9
p. 1814

Abstract

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Our therapeutic arsenal against viruses is very limited and the current pandemic of SARS-CoV-2 highlights the critical need for effective antivirals against emerging coronaviruses. Cellular assays allowing a precise quantification of viral replication in high-throughput experimental settings are essential to the screening of chemical libraries and the selection of best antiviral chemical structures. To develop a reporting system for SARS-CoV-2 infection, we generated cell lines expressing a firefly luciferase maintained in an inactive form by a consensus cleavage site for the viral protease 3CLPro of coronaviruses, so that the luminescent biosensor is turned on upon 3CLPro expression or SARS-CoV-2 infection. This cellular assay was used to screen a metabolism-oriented library of 492 compounds to identify metabolic vulnerabilities of coronaviruses for developing innovative therapeutic strategies. In agreement with recent reports, inhibitors of pyrimidine biosynthesis were found to prevent SARS-CoV-2 replication. Among the top hits, we also identified the NADPH oxidase (NOX) inhibitor Setanaxib. The anti-SARS-CoV-2 activity of Setanaxib was further confirmed using ACE2-expressing human pulmonary cells Beas2B as well as human primary nasal epithelial cells. Altogether, these results validate our cell-based functional assay and the interest of screening libraries of different origins to identify inhibitors of SARS-CoV-2 for drug repurposing or development.

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