Influenza A virus hemagglutinin protein, H7N1 subtype (HA)

The Influenza A virus hemagglutinin (HA) protein of the H7N1 subtype is a critical surface glycoprotein that mediates viral entry into host cells. It functions as a homotrimer, where each monomer consists of two subunits, HA1 and HA2, produced by the proteolytic cleavage of a precursor HA0 (UniProt Q5QSZ6). The HA1 subunit contains the receptor-binding site (RBS) that recognizes sialic acid on host cell membranes, while the HA2 subunit contains the fusion peptide responsible for merging the viral envelope with the endosomal membrane under acidic conditions (Wikipedia). H7N1 is particularly significant as a highly pathogenic avian influenza (HPAI) subtype that has caused major outbreaks in poultry and poses a zoonotic threat to humans (CDC). Therapeutic strategies targeting HA include neutralizing antibodies that block receptor attachment or fusion, and small-molecule inhibitors like Umifenovir that stabilize the prefusion conformation (PubMed). Vaccines remain the primary tool for prevention, though their efficacy is frequently challenged by the rapid antigenic evolution of the protein through drift and shift (NIH).

Other names

HemagglutininHAH7H7N1 HASurface glycoprotein

Inhibition of viral entry by blocking receptor binding (head-targeting antibodies) or preventing low-pH induced membrane fusion (stalk-targeting antibodies and small molecules like Umifenovir).