Ida Paciello, Emily J. Rundlet, Ling Zhou, Giulia Realini, Federica Perrone, Giulio Pierleoni, Marco Troisi, Jeanne Postal, Florence Guivel‐Benhassine, Françoise Porrot, Connor M. Mullins, Davide Moschese, Maria Vittoria Cossu, Federico Sabaini, Silvia Accordini, Natasha Gianesini, Rebeca Passarelli Mantovani, Francesca Panza, Massimiliano Fabbiani, Mario Tumbarello, Spinello Antinori, Concetta Castilletti, Francesca Montagnani, Olivier Schwartz, Rino Rappuoli, Jason S. McLellan, Emanuele Andreano
Recurrent mpox outbreaks caused by the monkeypox virus (MPXV) have prompted the World Health Organization to declare a Public Health Emergency of International Concern and have stimulated the development of medical interventions. Here, we used antigen-agnostic identification of MPXV-neutralizing monoclonal antibodies from convalescent or vaccinated people, AlphaFold 3-based predictive modeling, and cryo-electron microscopy to identify the protein encoded by orthopoxviral gene (OPG) 153 (MPXV A28) as a target of broadly neutralizing antibodies. OPG153-targeting antibodies neutralized MPXV clades Ib and IIb and vaccinia virus (VACV) and cross-reacted with OPG153 orthologs from cowpox and variola viruses. Immunization with MPXV OPG153 elicited a potent neutralizing antibody response against MPXV and VACV in mice, substantiating OPG153 as both a promising vaccine antigen and a potent target for preventive and therapeutic antibodies.