MPV is a double-stranded deoxyribonucleic acid (DNA) enveloped orthopoxvirus in the Poxviridae family . Poxvirus have brick or oval structures with oval or brick-shaped particles surrounded by a 200-400 nm lipoprotein outer membrane that is geometrically corrugated . Poxvirus invade host cells predominantly through three steps: adsorption, membrane fusion, and core invasion . F13, an extracellular virion (EV) protein of the vaccinia virus, plays a crucial role in the regulation of glycoprotein incorporation . F13 is the most abundant envelope protein on the extracellular membrane of virus. The phospholipase protein F13 of the vaccinia virus promotes the rapid entry of extracellular virus into cells . The F13 protein lacks a transmembrane domain, but cysteine residues 185 and 186 are palmitoylated . Poxvirus F13's complete crystal structure has not been determined . F13 plays an important role in membrane binding, virion wrapping, and extracellular envelope virus (EEV) production .