Hemagglutinin H7 (Influenza A virus) (H7 HA)

Hemagglutinin H7 is a primary surface glycoprotein of the Influenza A virus H7 subtype, serving as a critical mediator of viral infection by facilitating host cell attachment and membrane fusion (UniProt, 2024). It is a trimeric Class I fusion protein that binds to sialic acid receptors on the host cell surface, triggering endocytosis; subsequently, the low pH environment of the endosome induces an irreversible conformational change in the HA2 subunit, leading to the fusion of viral and endosomal membranes (MDPI, 2020). H7 is categorized as a Group 2 hemagglutinin and is notably associated with highly pathogenic avian influenza (HPAI) strains, such as H7N9, which have caused severe zoonotic outbreaks in humans characterized by pneumonia and high mortality rates (NIH, 2025). Unlike seasonal influenza, H7 viruses often exhibit ocular tropism, leading to conjunctivitis in addition to respiratory symptoms (NIH, 2024). Therapeutic interventions targeting H7 HA include vaccines, broadly neutralizing monoclonal antibodies (e.g., VIS410, MEDI8852) that target the conserved stalk region, and small molecules like Arbidol or Nitazoxanide that inhibit fusion or protein maturation (NIH, 2020; MDPI, 2024). The target's high rate of antigenic drift and the potential for pandemic spread necessitate ongoing development of universal inhibitors and surveillance of emerging mutations (NIH, 2025; MDPI, 2023).

Other names

H7 hemagglutininH7 HAHemagglutinin H7HA7Influenza A virus H7 hemagglutininH7 subtype hemagglutinin

Drugs targeting H7 hemagglutinin primarily act as entry inhibitors by either blocking the receptor-binding site on the HA1 head to prevent attachment or binding to the conserved HA2 stalk to inhibit the pH-dependent conformational change required for membrane fusion (NIH, 2020; MDPI, 2020). Additionally, some agents like Nitazoxanide interfere with the post-translational maturation and intracellular transport of the HA protein to the host cell membrane (NIH, 2025).