Hemagglutinin (Influenza A virus H1N1 pandemic 2009) (HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the 2009 H1N1 pandemic influenza A virus, playing a critical role in the viral life cycle (UniProt C3W5S1). It mediates the initial attachment of the virus to host cells by binding to α2,6-linked sialic acid receptors in the human upper respiratory tract (PubMed 22718832). Following endocytosis, HA undergoes a pH-dependent conformational change that facilitates the fusion of the viral envelope with the endosomal membrane, allowing the viral genome to enter the cytoplasm (PubMed 23342166). As the major antigen on the viral surface, HA is the primary target for neutralizing antibodies induced by infection or vaccination (PubMed 20364149). The 2009 pandemic strain (pH1N1) featured an antigenically novel globular head but a relatively conserved stalk region compared to previous seasonal H1N1 strains (PubMed 32581106). Therapeutic strategies targeting HA include seasonal and pandemic vaccines, broadly neutralizing monoclonal antibodies that target the conserved stalk, and small-molecule fusion inhibitors like Umifenovir (PubMed 23342166). Monitoring HA through hemagglutination inhibition assays is standard for assessing vaccine efficacy and viral evolution (PubMed 21123531).

Other names

H1HA1HA209H1pH1N1 HASwine flu hemagglutininHemagglutinin glycoprotein

Inhibition of viral attachment to host cell sialic acid receptors and inhibition of pH-dependent membrane fusion between the viral envelope and the host endosomal membrane.