Hemagglutinin protein of Influenza B

Hemagglutinin (HA) is the major surface glycoprotein of the influenza B virus. It mediates attachment to host cells and fusion between viral and cellular membranes, enabling viral infectivity. HA is a trimeric protein composed of HA1 and HA2 subunits and is a primary target for neutralizing antibodies, making it crucial for immune recognition and vaccine design. It binds to sialic acid-containing receptors on host cells, initiating endocytosis. Acidic pH in the endosome triggers conformational changes in HA, leading to membrane fusion and release of viral RNA into the cytoplasm. HA is highly variable due to antigenic drift, necessitating frequent updates to influenza vaccines.

Inhibition of hemagglutinin prevents viral attachment and entry into host cells.