Hemagglutinin (Influenza A virus H1N1 subtype) (HA)

Hemagglutinin (HA) is a homotrimeric surface glycoprotein of the influenza A virus H1N1 subtype that is essential for viral entry into host cells (Wikipedia, 2024). It functions as a lectin by binding to sialic acid-containing receptors on the surface of host respiratory epithelial cells, which triggers receptor-mediated endocytosis (NIH, 2013). Within the acidic environment of the endosome, HA undergoes a major conformational change that facilitates the fusion of the viral envelope with the endosomal membrane, releasing the viral ribonucleoproteins into the cytoplasm (MDPI, 2021). As the primary antigen on the viral surface, HA is the principal target for neutralizing antibodies induced by seasonal and pandemic influenza vaccines (NIH, 2021). Therapeutic strategies targeting HA include small molecule fusion inhibitors like umifenovir and broadly neutralizing monoclonal antibodies, such as CR6261, that aim to provide protection across multiple influenza strains (NIH, 2013; MDPI, 2023). However, the rapid evolution of HA through antigenic drift and shift poses a significant challenge, requiring continuous surveillance and periodic updates to vaccine formulations to prevent strain mismatch (MDPI, 2021; Medscape, 2023).

Other names

H1 HemagglutininHA1/HA2 glycoproteinInfluenza A virus H1N1 surface glycoproteinHemagglutinin proteinSurface glycoprotein

Inhibition of viral attachment to host cell sialic acid receptors and prevention of pH-dependent membrane fusion within the endosome.