Influenza hemagglutinin and neuraminidase (HA and NA)

Influenza hemagglutinin and neuraminidase are the two major glycoproteins found on the surface of influenza viruses, essential for infectivity and viral propagation. Hemagglutinin is responsible for binding to sialic acid-containing receptors on host cells and mediating the fusion of the viral and host membranes, which allows the viral genome to enter the host cell[1][7]. Neuraminidase is an enzyme that cleaves sialic acid residues from glycoproteins on the viral and host cell surfaces, facilitating the release of newly formed viral particles and preventing viral aggregation[2][3][6]. The combination of hemagglutinin and neuraminidase subtypes (e.g., H1N1, H3N2) defines the major influenza A virus strains and their epidemiological significance[7]. Both proteins are key targets for antiviral drugs and vaccines: neuraminidase is inhibited by drugs like oseltamivir and zanamivir, while hemagglutinin is the primary target of neutralizing antibodies induced by infection or vaccination[2][5][7]. Rapid and frequent genetic changes in both proteins underlie influenza’s capacity for seasonal epidemics and occasional pandemics[2][6][7].

Other names

hemagglutinin (HA)neuraminidase (NA)influenza envelope glycoproteinsinfluenza surface antigens

Neuraminidase inhibitors block sialic acid cleavage, preventing viral release from cells[2][5] Neutralizing antibodies block the binding or fusion activity of hemagglutinin, preventing viral entry or fusion[1][7] Small molecules/antibodies targeting hemagglutinin may prevent receptor recognition or membrane fusion[1][7]