Influenza virus surface glycoproteins (Hemagglutinin and Neuraminidase) (HA/NA)

Influenza virus surface glycoproteins, specifically hemagglutinin (HA) and neuraminidase (NA), are the primary targets for both prophylactic vaccines and certain therapeutic interventions (CDC, 2022; WHO, 2023). Hemagglutinin is a lectin that facilitates viral attachment to host cell sialic acid receptors and mediates membrane fusion, while neuraminidase is an enzyme that cleaves these receptors to allow the release of newly formed virions (UniProt, 2024; Gamblin & Skehel, 2010). Vaccines utilize these antigens to stimulate a polyclonal immune response, resulting in the production of antibodies that neutralize the virus and provide protection against infection (StatPearls, 2023). Due to the high rate of mutation in these proteins, known as antigenic drift, vaccine formulations must be reviewed and updated annually to ensure a match with circulating strains (WHO, 2023). In addition to vaccines, neuraminidase serves as a direct target for antiviral drugs which inhibit the enzymatic activity required for viral dissemination within the respiratory tract (von Itzstein, 2007). The induction of a broad polyclonal response is critical for effective immunity, as it targets multiple epitopes on the viral surface (CDC, 2022).

Other names

Influenza antigensFlu surface proteinsHemagglutininNeuraminidaseViral surface glycoproteins

Vaccines containing these antigens induce a polyclonal immune response, primarily generating neutralizing antibodies that bind to hemagglutinin to prevent viral entry and neuraminidase to limit viral spread (CDC, 2022). Antiviral drugs like neuraminidase inhibitors (e.g., oseltamivir) competitively bind to the active site of the neuraminidase enzyme to prevent the release of new viral particles from infected cells (StatPearls, 2023).