Hemagglutinin (HA) (H7N9 influenza A virus) (HA)

Hemagglutinin (HA) is the primary surface glycoprotein of the H7N9 influenza A virus, playing a critical role in viral entry by binding to host cell sialic acid receptors and mediating the fusion of the viral envelope with the endosomal membrane (UniProt, Wikipedia). It is a class I fusion protein composed of two subunits, HA1 and HA2, which are generated by the proteolytic cleavage of a precursor protein, HA0 (Wikipedia, MDPI). The H7N9 subtype is of significant public health concern due to its high mortality rate in humans—approximately 40%—and its potential for zoonotic transmission and pandemic spread (NIH, WHO). HA is the principal target for the host immune response and the primary component of influenza vaccines (NIH, MDPI). Therapeutic strategies targeting HA include neutralizing monoclonal antibodies like MEDI8852 and VIS-410, which bind to the conserved stalk region, and small molecule inhibitors such as Umifenovir and Nitazoxanide that interfere with fusion or protein trafficking (ASM, Atlas of Science). However, the rapid antigenic drift and the emergence of highly pathogenic strains with polybasic cleavage sites pose ongoing challenges for vaccine efficacy and antiviral development (NIH, J. Virol).

Other names

HAH7 HAH7N9 HAHemagglutinin proteinHemagglutinin glycoproteinH7N9 Hemagglutinin

Inhibition of viral attachment to host sialic acid receptors and blocking of membrane fusion by preventing the low-pH-induced conformational changes in the HA2 subunit (Wikipedia, PatSnap). Some agents also impair the intracellular trafficking of the HA protein to the host cell membrane (Atlas of Science).