An allosteric inhibitor of the Zika virus NS2B-NS3 protease with oral efficacy in mouse models

  • Nat Commun. 2026 Feb 10;17(1):1439. doi: 10.1038/s41467-026-68943-x.
Jesus M Ontoria  1 ,  Esther Torrente  2 ,  Antonino Missineo  3 ,  Cristina Alli  3 ,  Rita Graziani  3 ,  Silvia Conti  3 ,  Monica Bisbocci  3 ,  Antonio Quotadamo  2 ,  Federica Ferrigno  2 ,  Alessandra Corio  2 ,  Giovanni Ievoli  2 ,  Leda Bencheva  2  4 ,  Jérôme Amaudrut  2 ,  Silvana Vasile  2 ,  Elisa Beghetto  3 ,  Chantal Paolini  3 ,  Nadine Alaimo  3 ,  Maria Veneziano  2 ,  Martina Nibbio  2 ,  Maria V Orsale  2 ,  Giulia Proto  2 ,  Fabrizio Colaceci  2 ,  Laura Orsatti  2 ,  Vincenzo Pucci  2  5 ,  Romano Di Fabio  2  6 ,  Licia Tomei  3 ,  Christian Montalbetti  2 ,  Alberto Bresciani  3  7 ,  Carlo Toniatti  8 ,  Giacomo Paonessa  9
Affiliations
  • 1. Department of Drug Discovery, IRBM S.p.A., Pomezia, Italy. [email protected].
  • 2. Department of Drug Discovery, IRBM S.p.A., Pomezia, Italy.
  • 3. Department of Biology and Translational Research, IRBM S.p.A., Pomezia, Italy.
  • 4. Sibylla Biotech S.p.A., Bresso, Italy.
  • 5. Johnson & Johnson, Beerse, Belgium.
  • 6. Drug Discovery Unit, Vita Salute San Raffaele University, Milan, Italy.
  • 7. Tycho S.r.l., Bergamo, Italy.
  • 8. CSO, IRBM S.p.A., Pomezia, Italy.
  • 9. Department of Biology and Translational Research, IRBM S.p.A., Pomezia, Italy. [email protected].
PMID: 41667483 DOI: 10.1038/s41467-026-68943-x
Abstract

The mosquito-transmitted Zika virus (ZIKV) poses a global health threat, with no approved Antiviral drugs or vaccines currently available. Here, we report the discovery of a series of ZIKV NS3 Protease Inhibitors identified through phenotypic high-throughput screening (HTS) using a ZIKV replicon-based cellular assay, and the subsequent selection of resistant mutants. These inhibitors, characterized by the presence of an N-acylsydnone imine group, bind to a previously undescribed allosteric pocket of the protease, locking the enzyme into a catalytically inactive conformation. We describe the characterization of IRBM-Z-1, our initial allosteric hit and IRBM-Z-2, a potent inhibitor of ZIKV infectivity and Other orthoflavivirus proteases with a favourable in vitro and in vivo ADME profile, resulting in oral efficacy against ZIKV Infection in mouse models, with potential as a prophylactic agent for human use.

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