Hemagglutinin protein Influenza B virus Yamagata lineage (HA (Influenza B Yamagata lineage))

The **hemagglutinin protein of Influenza B virus Yamagata lineage** is the major viral surface glycoprotein critical for the virus's ability to infect human cells. It mediates viral entry by binding to host sialic acid-containing receptors and triggers fusion of viral and cellular membranes. This protein is the principal target for neutralizing antibodies and an essential component in seasonal influenza vaccines. The Yamagata lineage, one of two antigenically distinct Influenza B lineages (the other being Victoria), has been defined by its unique hemagglutinin gene and antigenic structure. While both lineages can cause human disease and have been responsible for significant outbreaks, Yamagata lineage viruses have shown a slower rate of antigenic evolution than Victoria viruses, with periodic dominance and unique infection patterns, often affecting older adults more than children[2][5][6][7]. Importantly, surveillance has indicated that as of 2020, B/Yamagata lineage viruses may no longer be circulating in humans, likely due to pandemic public health interventions, and the World Health Organization has stopped recommending their inclusion in seasonal vaccines[7]. The HA protein’s antigenic properties underlie both vaccine design and immune escape, and rapid evolutionary changes can impair vaccine effectiveness. While HA is an attractive therapeutic target, most antiviral drugs for Influenza B target neuraminidase, with research ongoing into HA-specific therapeutics and monoclonal antibodies.

Other names

Influenza B virus hemagglutinin Yamagata lineageHA (B/Yamagata)Hemagglutinin B/Yamagata

Inhibition of receptor binding or membrane fusion (by neutralizing antibodies or entry inhibitors targeting HA[4]) Immune response targeting HA antigenicity (vaccination)