Quadrivalent influenza virus hemagglutinin and neuraminidase antigens (QIV antigens)

The target comprises the hemagglutinin (HA) and neuraminidase (NA) surface glycoproteins derived from four distinct influenza virus strains, typically including two influenza A subtypes (H1N1 and H3N2) and two influenza B lineages (Victoria and Yamagata). Hemagglutinin mediates viral entry by binding to sialic acid receptors on host cells and facilitating membrane fusion, whereas neuraminidase is an enzyme that cleaves these receptors to allow the release of progeny virions. These proteins serve as the primary antigens in quadrivalent influenza vaccines, designed to stimulate the production of neutralizing antibodies that provide seasonal immunity. Due to the high rate of antigenic drift in influenza viruses, the specific strains are reviewed and updated annually by the World Health Organization to ensure vaccine matching. Beyond vaccination, neuraminidase is a key therapeutic target for antiviral medications like oseltamivir and zanamivir, which block viral egress and limit the spread of infection within the respiratory tract. The quadrivalent approach ensures broader protection against the two co-circulating lineages of influenza B, significantly reducing the risk of vaccine mismatch compared to older trivalent formulations.

Other names

Quadrivalent influenza vaccine antigensQIV antigensInfluenza A and B HA/NA antigensH1N1, H3N2, B/Victoria, and B/Yamagata antigensInactivated influenza vaccine components

Induction of neutralizing antibodies against hemagglutinin and neuraminidase to block viral attachment and release; competitive inhibition of viral neuraminidase enzyme activity to prevent progeny virion egress.