Influenza A virus hemagglutinin H2 (HA (H2 subtype))

Influenza A virus hemagglutinin H2 is a homotrimeric transmembrane glycoprotein on the viral envelope, cleaved from the HA0 precursor into HA1 (receptor-binding globular head domain) and HA2 (stalk domain mediating membrane fusion). HA1 binds sialic acid receptors on host cells for attachment and endocytosis, while low pH in endosomes triggers HA2 conformational changes, releasing the N-terminal fusion peptide to fuse viral and endosomal membranes, enabling genome release.[1][2][3][4][6] The receptor-binding site (RBS) in HA1's head recognizes α2,6-linked sialic acids in human hosts, with conserved residues like Y98, W153, H183, Y195; the stalk (HA2) is more conserved across subtypes, targeted for universal vaccines.[1][2][3] H2 caused the 1957 pandemic (e.g., A/Japan/305/1957 H2N2 strain).[6]

Other names

H2 hemagglutininHA2 (subunit)Influenza A H2 HA