Viral protein involved in the entry of the entire virion, some of its contents or at least its genetic material into the host cell cytoplasm. Entry is achieved through pore formation, membrane fusion, pilus retraction, ejection, permeabilization and/or endocytosis mechanisms. Penetration reactions occur mainly in five locations: the cell membrane, early and late endosomes, caveosomes, and the ER. In prokaryotes, membrane fusion, pore formation through a puncturing device, ejection, pilus retraction or permeabilization occur at the plasma membrane, as well as at the outer membrane in prokaryotes with 2 membranes.

› Biological process

› viral entry into host cell [ GO:0046718 ]