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

Influenza B virus (Victoria lineage) hemagglutinin (HA) is the primary surface glycoprotein and a critical therapeutic target for the prevention of influenza B infections. As a class I viral fusion protein, HA mediates the initial attachment of the virus to sialic acid receptors on the host cell surface and facilitates the fusion of the viral and endosomal membranes to release the viral genome into the cytoplasm (UniProt, 2024; NIH, 2024). It is the major antigen in seasonal influenza vaccines, which are designed to induce neutralizing antibodies that primarily target the immunodominant globular head of the protein (WHO, 2024). However, the Victoria lineage HA undergoes frequent antigenic drift, particularly in key loops (120, 150, 160) and the 190-helix, which can lead to vaccine mismatch and reduced protection (NIH, 2024). Since the apparent extinction of the B/Yamagata lineage in 2020, B/Victoria has become the sole circulating lineage of influenza B, making its hemagglutinin the central focus for current vaccine formulations and the development of broadly neutralizing monoclonal antibodies like CR9114 (Wikipedia, 2024; NIH, 2024).

Other names

Influenza B Victoria lineage HAHemagglutinin protein (Influenza B Victoria)B/Victoria/2/87-like hemagglutininB/Victoria hemagglutininHA protein (Influenza B Victoria)

Neutralization of viral entry by blocking the receptor-binding site on the HA head or inhibiting the pH-dependent conformational change in the HA stalk required for membrane fusion (NIH, 2024; UniProt, 2024).