Hemagglutinin (HA) of pandemic H1N1 influenza virus (HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the pandemic H1N1 influenza virus, playing a critical role in the initial stages of viral infection (UniProt: C3W5X2). It functions as a class I fusion protein that mediates both the binding of the virus to alpha-2,6-linked sialic acid receptors on the host respiratory epithelium and the subsequent fusion of the viral envelope with the endosomal membrane (PubMed: 19443780). Structurally, HA exists as a homotrimer, where each monomer is cleaved into HA1 (receptor binding) and HA2 (fusion machinery) subunits (PDB: 3LZG). In the context of pandemic H1N1, HA is the principal target for neutralizing antibodies induced by vaccination or natural infection (CDC, 2023). Therapeutic strategies targeting HA include small-molecule fusion inhibitors like Umifenovir and broadly neutralizing monoclonal antibodies that target conserved regions of the HA stalk or head (DrugBank: DB06144). Monitoring HA mutations is essential for public health, as antigenic drift can lead to reduced vaccine efficacy and increased viral spread (WHO, 2024).

Other names

H1Hemagglutinin surface glycoproteinHA1/HA2 complexInfluenza A virus hemagglutinin

Inhibition of viral attachment to host cell sialic acid receptors and prevention of pH-dependent membrane fusion within the endosome.