Influenza A virus H7 hemagglutinin protein (H7 HA)

The Influenza A virus H7 hemagglutinin protein (H7 HA) is a major surface glycoprotein and a primary antigen of H7 subtype influenza viruses, such as H7N9 and H7N7 (UniProt). It exists as a homotrimeric class I fusion protein, where each monomer is composed of the HA1 subunit, responsible for binding to host cell sialic acid receptors, and the HA2 subunit, which mediates the fusion of the viral envelope with the endosomal membrane (PubMed: 24030494). H7 HA is a critical therapeutic target because neutralizing antibodies directed against its globular head or conserved stem region can prevent viral entry and infection (NIH: NIAID). While H7 viruses primarily circulate in avian populations, certain mutations in the H7 HA protein can increase affinity for human-type alpha 2,6-linked sialic acids, posing a significant pandemic threat (CDC). Consequently, H7 HA is the focus of intensive vaccine development and the engineering of broadly neutralizing antibodies like MEDI8852 (Nature: 10.1038/nature17417).

Other names

Hemagglutinin H7H7 proteinHA7Influenza A virus H7 HAH7N9 hemagglutinin

The protein mediates viral attachment to host cell sialic acid receptors via its HA1 subunit and facilitates membrane fusion between the viral envelope and the host endosomal membrane via its HA2 subunit following a pH-induced conformational change.