Influenza A virus hemagglutinin protein H1N1 (HA (H1N1))

The **Influenza A virus hemagglutinin protein H1N1** is a homotrimeric glycoprotein on the surface of the H1N1 strain of influenza A virus[1][3]. It mediates viral entry into host cells by binding to sialic acid-containing receptors on the cell surface and promoting membrane fusion after endocytosis and acidification[1][2][4][6]. HA is synthesized as an immature HA0 precursor which is cleaved into HA1 (responsible for receptor binding and antigenicity) and HA2 (mediating membrane fusion), both required for infectivity[2][4][6]. H1N1 hemagglutinin is the principal target of neutralizing antibodies and a focus of vaccine design. Its antigenic variability underlies influenza’s ability to evade the immune system, necessitating frequent vaccine reformulation[1][3][6]. Drugs and therapeutic antibodies aimed at HA seek to block either viral attachment or the subsequent membrane fusion step, but treatment options directly targeting HA remain largely experimental compared to established neuraminidase inhibitors.

Other names

hemagglutinin (H1N1)influenza H1 hemagglutininH1 HAHA H1 subtype

Inhibition of viral fusion (fusion inhibitors); Neutralization of viral attachment (monoclonal antibodies)