Hemagglutinin Protein (Influenza A) (HA)

Hemagglutinin (HA) is the most abundant glycoprotein on the surface of influenza A viruses. It is a class I viral fusion protein that plays a central role in both viral attachment to host cells and subsequent membrane fusion, enabling viral entry into the host cell cytoplasm. HA is also the primary antigen recognized by neutralizing antibodies, making it a major target for immune responses and vaccine development. It binds to sialic acid-containing receptors on host cells, initiating infection, and undergoes conformational changes in acidic environments to facilitate viral membrane fusion. Due to its critical role in infection, HA is a key target for antiviral drug development and vaccine design.

Other names

HA proteinInfluenza hemagglutininHA trimer

Inhibition of receptor binding; prevention of conformational changes required for membrane fusion