Avian influenza Matri, Xenopus/Amphibian, Protein-2 (H5N1-M2) forms a proton-selective ion channel that is necessary for the efficient release of the viral genome during virus entry. After attaching to the cell surface, the virion enters the cell by endocytosis. Acidification of the endosome triggers M2 ion channel activity. The influ, Xenopus/Amphibian, of protons into virion interior is believed to disrupt interactions between the viral ribonucleoprotein (RNP),Mouse,atri, Xenopus/Amphibian, protein 1 (M1), and lipid bilayers, thereby freeing the viral genome from interaction with viral proteins and enabling RNA segments to migrate to the host cell nucleus, where influenza virus RNA transcription and replication occur. The M2 protein from most influenza A strains is inhibited by amantadine and rimantadine, resulting in viral uncoating incapacity.