Influenza A virus hemagglutinin H3N2 subtype protein (HA (H3N2))

Influenza A virus hemagglutinin H3N2 subtype protein (HA) is a trimeric glycoprotein located on the surface of the influenza A virus, with each monomer comprising a globular head and a stem domain[1][7][10]. The head domain is responsible for binding to sialic acid-containing receptors on the host cell surface, determining host specificity, while the stem mediates fusion between the viral envelope and host cell membrane during entry[1][7][10]. Antigenic sites on the head domain overlap with the receptor-binding site and are highly variable, underlying antigenic drift and frequent vaccine updates[3][5][9]. HA is the principal target of neutralizing antibodies, and its continuous antigenic evolution presents a significant challenge to influenza prevention and control[3][9][10]. The specific antigen "A/Croatia/10136RV/2023" or "A/District of Columbia/27/2023-like" refers to recent human H3N2 virus reference strains used in contemporary vaccine formulations, reflecting the current circulating antigenic profile.

Other names

Influenza A hemagglutinin H3N2Influenza virus HA protein H3N2H3N2 HAHemagglutinin H3N2HA (H3N2)

Inhibition of virus-host membrane fusion (by neutralizing antibodies binding HA stem); Blockade of receptor-binding (neutralizing antibodies blocking HA head domain)[10]