Description | Viral protein involved in the merging of the virus envelope with host cytoplasmic membrane during viral penetration into host cell. Virus fusion proteins drive this fusion reaction by undergoing a major conformational change that is triggered by interactions with the target cell. This pathway is used by viruses whose fusion protein is usually pH independent such as most paramyxoviruses, herpesviruses and retroviruses. MHV-JHM coronavirus has been shown to fuse directly with the host cytoplasmic membrane. Prokaryotic viruses such as Tectiviridae fuse their inner membrane with the host cytoplasmic membrane whereas Cystoviridae fuse their outer membrane with the host cytoplasmic membrane |