Monkeypox virus is an Orthopoxvirus, a genus that includes camelpox, cowpox, vaccinia, and variola viruses. Monkeypox A35R is a homolog of Vaccinia virus A33R protein. A33R is specifically incorporated into the viral outer envelope. The protein is expressed early and late after infection, cosistent with putative early and late promoter sequences. And it is necessay for efficient cell-to-cell spread. It is reported that the protective efficacy afforded by anti-A33R MAb against vaccinia virus was comparable to that of anti-MPXV B5R MAb. Anti-MPXV A35R mAb is a human monoclonal antibody and is produced by mammalian expression system.