Influenza B virus hemagglutinin (HA) (Victoria lineage) (HA)

Influenza B virus hemagglutinin (HA) is a primary surface glycoprotein essential for the viral infection cycle, specifically within the Victoria lineage (often designated as Lineage 2). HA functions as a homotrimeric class I fusion protein that mediates both host cell attachment and membrane fusion (UniProt P03460). The protein's head domain binds to sialic acid receptors on the respiratory epithelium, while the stem domain undergoes a dramatic conformational change at low pH to facilitate viral entry (PubMed 25733861). As the dominant antigen on the viral surface, HA is the primary target for neutralizing antibodies induced by seasonal quadrivalent influenza vaccines (CDC, 2023). Therapeutic efforts targeting this molecule include the development of broadly neutralizing monoclonal antibodies, such as CR9114, which bind to the conserved stem region to prevent fusion across multiple influenza lineages (Science, 2012). Additionally, small-molecule inhibitors like Umifenovir target the HA-mediated fusion process to inhibit viral replication (PubMed 30812941). The continuous evolution of HA through antigenic drift remains a significant challenge, necessitating ongoing surveillance and periodic vaccine strain updates to maintain clinical efficacy.

Other names

Influenza B hemagglutinin – B lineage 2B/Victoria/2/87-like hemagglutininLineage II hemagglutininVictoria lineage HAHemagglutinin

Inhibition of viral attachment and membrane fusion