Hemagglutinin of Influenza A H5N1 (HA (H5N1))

Hemagglutinin of Influenza A H5N1 is a viral surface glycoprotein essential for the attachment of the virus to host cells and subsequent membrane fusion, mediating entry of the viral genome into the host cell. HA is composed of a globular head containing the receptor-binding site (RBS) and a stem/domain involved in membrane fusion. Its primary cellular receptors are sialylated glycans: avian H5N1 HA prefers α2,3-linked sialic acids, while specific amino acid mutations (notably at residue 226, Gln→Leu) can shift specificity toward α2,6-linked human-type receptors, a key determinant of host range and pandemic potential[1][3][4][5][6][9]. HA is the main antigenic target for neutralizing antibodies and vaccines, with several vulnerable epitopes identified on its head and stem regions[2]. Monitoring HA mutations is critical for surveillance, as changes may impact virulence, transmissibility, and effectiveness of immunotherapeutics[5][9].

Other names

Influenza hemagglutinin H5H5 hemagglutininH5N1 HAHemagglutinin protein of influenza A virus subtype H5N1

Neutralizing antibodies bind receptor-binding site (RBS) or stem domain of HA to block attachment or membrane fusion[2]. Drugs/vaccines target HA to prevent receptor engagement or fusion with host cell membrane.