HA (hemagglutinin) gene

The HA (hemagglutinin) gene encodes a protein called hemagglutinin found on the surface of influenza viruses. This protein is crucial for the virus's ability to infect host cells because it binds to receptors on the cell surface, allowing entry. Hemagglutinin also determines how the immune system recognizes the virus, influencing vaccine effectiveness. Variations in the HA gene lead to changes in the virus's surface protein, which can result in new strains that evade immunity. Therefore, studying the HA gene helps scientists track and predict influenza outbreaks and develop effective vaccines.