Hemagglutinin (HA) from Influenza A virus H7N9 subtype (H7 HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the Influenza A virus H7N9 subtype and is essential for viral entry into host cells. It functions as a homotrimeric lectin that recognizes and binds to sialic acid receptors on the host cell surface, specifically showing an evolved affinity for human-type alpha-2,6-linked sialic acids in H7N9 strains (UniProt P0CG37; PubMed: 23788230). Following endocytosis, a low-pH-induced conformational change in the HA2 subunit triggers the fusion of the viral envelope with the endosomal membrane, releasing the viral genome into the cytoplasm (PubMed: 24037376). As the major antigen of the virus, HA is the principal target for neutralizing antibodies and the primary component of seasonal and pandemic vaccines (NIH/NIAID). Therapeutic development focuses on monoclonal antibodies that target the conserved stem region to provide broad protection across different influenza subtypes, as well as small molecules designed to inhibit the fusion process (PubMed: 28123353).

Other names

H7 hemagglutininHA proteinInfluenza A virus (A/Anhui/1/2013(H7N9)) hemagglutininSurface glycoprotein

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