Mpox virus myristoylated membrane protein M1R (M1R)

Mpox virus myristoylated membrane protein M1R (M1R) is a highly conserved, myristoylated membrane protein located on the surface of the intracellular mature virion (IMV) of mpox virus (Monkeypox virus, MPXV). M1R is homologous to the vaccinia virus L1R protein (about 98.4% identity) and is required for the assembly and cellular entry of viral particles, acting as a key component of the putative entry fusion complex (EFC) involved in membrane fusion and virus-host cell penetration. M1R presents conformational B-cell epitopes and is a major target for neutralizing antibodies elicited by natural infection or by experimental vaccines; it has been shown that M1R-specific monoclonal antibodies or recombinant protein vaccines can induce strong humoral and cellular immune responses and protect animals from mpox challenge. Due to its surface accessibility and immunodominant properties, M1R is studied both as a therapeutic target for antibody development and as a major antigen for subunit vaccine design. There are no currently approved drugs targeting M1R, but several experimental antibodies and vaccine candidates are in preclinical development.

Other names

Mpox virus M1RMonkeypox virus M1RMPXV M1RMyristoylated IMV membrane protein (homolog of L1R in vaccinia virus)

Neutralizing antibodies block virus entry by binding to conformational epitopes on M1R, preventing attachment/fusion with host cells. Experimental vaccines induce antibody and Th1 cellular immune responses targeting M1R. Bivalent antibody fragments (VHHs) increase neutralization by high affinity binding.