Hemagglutinin of Influenza A H1N1 (HA)

Hemagglutinin of Influenza A H1N1 is a trimeric, surface glycoprotein essential for both viral attachment to host cells and subsequent membrane fusion, enabling infection and spread[1][3][2][5][7]. Its globular "head" domain binds to sialic acid receptors, determining host tropism, while the "stem" domain mediates viral-host membrane fusion under low pH conditions in endosomes[1][2][5]. Hemagglutinin is the primary antigenic target for immune responses and vaccines, and antigenic diversity in the HA gene is responsible for seasonal influenza variation and pandemic potential[3][1][5]. Inhibition of HA—either by neutralizing antibodies, vaccine-induced immunity, or experimental fusion blockers—is a mainstay of influenza prevention and therapeutic strategies[3][1][5]. Antigenic drift, caused by mutations in the HA gene, poses continual challenges for vaccine effectiveness and antibody therapeutics[5][3][1].

Other names

HemagglutininHAInfluenza hemagglutininH1 hemagglutininHemagglutinin protein

Inhibition of receptor binding (antibodies, vaccines prevent viral attachment to host cells). Inhibition of membrane fusion (some antibodies disrupt conformational changes needed for fusion). Blockage of HA-mediated entry prevents viral replication and spread.