Hemagglutinin Protein of Influenza A Virus Subtype H5 (HA (H5))

Hemagglutinin (HA) is a trimeric glycoprotein on the surface of influenza A viruses, including subtype H5. It mediates viral infectivity by attaching to host cells via sialic acid binding and facilitating fusion of the viral envelope with the host cell membrane. HA exists as a homotrimer composed of HA1 and HA2 subunits. The globular head domain (HA1) contains the receptor-binding site and is the primary target for neutralizing antibodies. The stem domain (HA2) anchors the protein in the viral membrane and mediates membrane fusion. H5 belongs to group 1 hemagglutinins. Highly pathogenic avian influenza A(H5N1) can infect humans, and mutations in hemagglutinin can alter receptor specificity, potentially increasing human transmissibility. The HA gene resides on one segment of influenza A's RNA genome. Mutations near cleavage sites or receptor-binding domains can affect virulence, transmissibility, and vaccine effectiveness.

Other names

H5 hemagglutininInfluenza A H5 hemagglutininHA protein (H5 subtype)

Entry inhibition (targeted by neutralizing antibodies)