Influenza A virus hemagglutinin (H1N1 2009 pandemic strain) (HA)

Influenza A virus hemagglutinin (HA) is the primary surface glycoprotein of the 2009 H1N1 pandemic strain, serving as a critical mediator of viral entry into host cells (UniProt: C3W5X2). It functions by binding to alpha-2,6-linked sialic acid receptors on human respiratory epithelial cells, followed by a pH-induced conformational change in the endosome that triggers membrane fusion (PubMed: 19465683). Because HA is the main target for neutralizing antibodies, it is the essential component of influenza vaccines and a focal point for the development of novel antiviral therapies (Nature: 10.1038/nature08157). Drugs and antibodies targeting HA, such as Umifenovir, aim to either block the receptor-binding site or stabilize the protein's prefusion state to prevent the release of the viral genome into the host cytoplasm (DrugBank: DB13609). Understanding the structural evolution of this specific HA variant is vital for monitoring pandemic potential and ensuring the efficacy of seasonal vaccines.

Other names

H1 hemagglutinin2009 H1N1 HApdm09 HAHemagglutinin HA1/HA2Surface glycoprotein HA

Inhibition of viral entry by blocking the binding of the HA1 subunit to host sialic acid receptors or by preventing the pH-dependent conformational change of the HA2 subunit required for fusion of the viral envelope with the endosomal membrane (PubMed: 19465683, 21666016).