Influenza A virus H7 hemagglutinin (H7 HA)

Influenza A H7 hemagglutinin (HA) is a major surface glycoprotein of H7 subtype influenza viruses, including the zoonotic and highly pathogenic H7N9 strain. It is synthesized as a precursor (HA0) that must be proteolytically cleaved into HA1 and HA2 subunits to become fusion-competent, forming a homotrimeric spike on the viral envelope (Shi et al., Science 2013). While the receptor-binding site (RBS) on the HA1 head is the primary target for strain-specific neutralizing antibodies, it is highly susceptible to antigenic drift. Non-RBS epitopes, particularly those located in the conserved HA2-dominated stem region or specific lateral patches on the HA1 subunit, serve as critical targets for broadly neutralizing antibodies (bnAbs) like MEDI8852 and CR9114 (Kallewaard et al., Cell 2016; Dreyfus et al., Science 2012). These non-RBS directed therapies typically function by sterically blocking the low-pH-induced conformational changes required for membrane fusion or by preventing the initial cleavage of HA0, offering a broader spectrum of protection against diverse H7 lineages and other influenza subtypes (Wang et al., J Virol 2015).

Other names

H7 hemagglutininInfluenza A H7 HAH7N9 hemagglutininHA1/HA2 subunitsHemagglutinin H7 subtype

Inhibition of viral-host membrane fusion, inhibition of HA0 cleavage, and neutralization of viral entry by targeting conserved epitopes outside the receptor-binding site.