Human monoclonal antibodies from donors vaccinated with recombinant vaccinia vaccine targeting A35 and B6 effectively inhibit orthopoxvirus spread and infection

The global Monkeypox (Mpox) outbreak remains ongoing, yet specific therapeutics are still limited. Monkeypox virus (MPXV) proteins A35 and B6 are known to mediate viral cell-to-cell spread within the host. Here, we isolated human monoclonal antibodies (mAbs) targeting MPXV A35 and B6 proteins from the donors received recombinant vaccinia vaccine (rTV). Both A35 mAbs (A35A3, A35A9) and B6 mAbs (B6H1, B6G1) exhibited cross-binding activity against vaccinia virus(VACV) and MPXV, and inhibited cell-to-cell spread of both viruses in vitro. In murine VACV challenge models, A35A3, A35A9, B6H1, and B6G1 conferred significant protection in therapeutic administration. In summary, this study identified four promising candidate mAbs, providing valuable insights for the treatment of orthopoxvirus infections, warranting further validation in MPXV challenge models.