Influenza A virus H3N2 hemagglutinin (H3 HA) (H3 HA)

Influenza A virus H3N2 hemagglutinin (HA) is a critical surface glycoprotein that mediates viral entry by binding to sialic acid receptors on host respiratory epithelial cells (UniProt: P03437). It is the primary target for the host's immune system, specifically for B-cell receptors (BCRs) and the resulting neutralizing antibodies (nAbs) produced during infection or vaccination (PubMed: 30104441). The HA molecule is a homotrimer consisting of a globular head (HA1) and a stalk region (HA2); the head is the site of most neutralizing epitopes but is highly prone to antigenic drift (Nature: 10.1038/nature10374). This rapid evolution allows H3N2 strains to evade existing immunity, making it a major cause of seasonal influenza morbidity and mortality (CDC: Influenza Virus Genome and Proteins). Therapeutic interventions, such as seasonal vaccines, aim to elicit nAbs that block the receptor-binding site or prevent the conformational changes required for viral-host membrane fusion (Science: 10.1126/science.aam5757). Research into broadly neutralizing antibodies often targets the more conserved HA stalk to develop universal influenza vaccines (Cell: 10.1016/j.cell.2018.11.005).

Other names

H3N2 HemagglutininHemagglutinin H3HA protein (H3N2)Influenza A virus (A/Hong Kong/1/1968(H3N2)) hemagglutinin

Neutralization of viral entry by blocking the interaction between the hemagglutinin globular head and host cell sialic acid receptors, or by inhibiting the pH-induced conformational change in the HA stalk required for membrane fusion.