Influenza virus hemagglutinin subunit HA1 (HA1) (HA1)

The Influenza virus hemagglutinin subunit HA1 is the globular head domain of the hemagglutinin (HA) glycoprotein, which serves as the primary surface antigen of the influenza virus (UniProt P03437). It plays a critical role in the initial stages of viral infection by mediating the attachment of the virus to sialic acid receptors on the surface of host respiratory epithelial cells (PMID: 29439178). Because it is the most exposed part of the virus, HA1 is the primary target for neutralizing antibodies generated by natural infection or seasonal vaccination (NIH, 2023). However, HA1 is also highly plastic and subject to frequent mutations, a process known as antigenic drift, which allows the virus to evade the host immune system and necessitates the annual updating of influenza vaccines (StatPearls, 2023). In addition to vaccines, HA1 is a target for the development of novel entry inhibitors and monoclonal antibodies designed to block viral attachment and neutralize infection (PubMed: 31235500). Understanding the structure and variability of HA1 is essential for pandemic preparedness and the development of universal influenza vaccines.

Other names

Hemagglutinin HA1 chainHA1 domainInfluenza HA1 subunitViral attachment protein HA1HA1 polypeptide

Inhibition of viral attachment to host cell sialic acid receptors and neutralization of viral entry.