A multivalent mRNA monkeypox virus vaccine (BNT166) protects mice and macaques from orthopoxvirus disease.

In response to the 2022 outbreak of mpox driven by unprecedented human-to-human monkeypox virus (MPXV) transmission, we designed BNT166, aiming to create a highly immunogenic, safe, accessible, and scalable next-generation vaccine against MPXV and related orthopoxviruses. To address the multiple viral forms and increase the breadth of immune response, two candidate multivalent mRNA vaccines were evaluated pre-clinically: a quadrivalent vaccine (BNT166a; encoding the MPXV antigens A35, B6, M1, H3) and a trivalent vaccine (BNT166c; without H3). Both candidates induced robust T cell responses and IgG antibodies in mice, including neutralizing antibodies to both MPXV and vaccinia virus. In challenge studies, BNT166a and BNT166c provided complete protection from vaccinia, clade I, and clade IIb MPXV. Furthermore, immunization with BNT166a was 100% effective at preventing death and at suppressing lesions in a lethal clade I MPXV challenge in cynomolgus macaques. These findings support the clinical evaluation of BNT166, now underway (NCT05988203). [Display omitted] • BNT166 is a multivalent mRNA orthopoxvirus vaccine encoding MPXV antigens A35, B6, M1, H3 • It elicits robust antibody and T cell responses to EV and MV antigens • Immunization protects mice from VACV, clade I and IIb MPXV, and NHPs from clade I MPXV • Clinical evaluation of BNT166 safety and immunogenicity is ongoing (NCT05988203) In 2022–2023, unprecedented outbreaks of clades I and IIb monkeypox virus driven by human-to-human transmission demonstrated a need for rapidly scalable and deployable vaccines against orthopoxviruses. BNT166 is a multivalent mpox mRNA vaccine that shows efficacy in multiple preclinical models, supporting its further study in clinical trials. [ABSTRACT FROM AUTHOR]