An allosteric inhibitor of the Zika virus NS2B-NS3 protease with oral efficacy in mouse models
- Jesus M. Ontoria
- Esther Torrente
- Antonino Missineo
- Cristina Alli
- Rita Graziani
- Silvia Conti
- Monica Bisbocci
- Antonio Quotadamo
- Federica Ferrigno
- Alessandra Corio
- Giovanni Ievoli
- Leda Bencheva
- Jérôme Amaudrut
- Silvana Vasile
- Elisa Beghetto
- Chantal Paolini
- Nadine Alaimo
- Maria Veneziano
- Martina Nibbio
- Maria V. Orsale
- Giulia Proto
- Fabrizio Colaceci
- Laura Orsatti
- Vincenzo Pucci
- Romano Di Fabio
- Licia Tomei
- Christian Montalbetti
- Alberto Bresciani
- Carlo Toniatti
- Giacomo Paonessa
2026-02-10
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.