H7 subtype hemagglutinin of H7N9 avian influenza A virus (H7 HA) (H7 HA)

The H7 subtype hemagglutinin (HA) of the H7N9 avian influenza A virus is a critical surface glycoprotein that mediates viral entry into host cells. It functions as a homotrimeric protein, where each monomer consists of a globular head responsible for receptor binding and a stem region that facilitates membrane fusion (UniProt: V5LXD8). In H7N9, the HA protein has evolved to bind both avian-type (alpha 2-3) and human-type (alpha 2-6) sialic acid receptors, which enhances its zoonotic potential and ability to infect humans (NIH: PMC3758897). Upon binding and endocytosis, the acidic environment of the endosome triggers a dramatic conformational change in the HA stem, leading to the fusion of viral and host membranes (PubMed: 23698299). This process is a primary target for therapeutic intervention, including the development of neutralizing monoclonal antibodies and small-molecule fusion inhibitors like Arbidol (NIH: PMC5226135). Additionally, the HA protein is the main component of influenza vaccines, although the H7 subtype is known for its relatively low immunogenicity, often necessitating the use of adjuvants to elicit a protective immune response (NIH: PMC6475508).

Other names

HemagglutininHAH7 HAH7N9 HAH7 hemagglutininH7N9 hemagglutininInfluenza A virus H7N9 hemagglutinin

H7 HA mediates viral entry by binding to host cell sialic acid receptors; subsequent endosomal acidification triggers a conformational change that facilitates membrane fusion between the virus and the host cell.