Influenza A and B virus hemagglutinin and neuraminidase proteins (Hemagglutinin (HA) and Neuraminidase (NA))

Hemagglutinin (HA) is a trimeric surface glycoprotein on influenza viruses that mediates viral attachment to host cell sialic acid receptors and facilitates membrane fusion during viral entry[1][2][6]. Neuraminidase (NA) is a tetrameric enzyme that cleaves terminal sialic acids from host cell glycoproteins and glycolipids to allow newly formed viruses to detach and spread to new cells[3][5][7]. Both proteins undergo frequent genetic changes (antigenic drift and shift), resulting in new strains with altered antigenicity, virulence, and host specificity[3][4][5]. Antibodies targeting HA block virus entry, while antibodies or drugs acting on NA prevent viral release. Vaccines and antivirals for influenza typically target one or both of these antigens, making them central to the prevention and treatment of seasonal and pandemic influenza.

Other names

Influenza hemagglutinin (HA)influenza HAInfluenza neuraminidase (NA)influenza NAInfluenza surface antigensH1N1H3N2flu antigens

Neuraminidase inhibitors: block NA sialidase activity, prevent release and spread of virus, reduce viral replication Anti-hemagglutinin antibodies: neutralize virus by blocking receptor binding and fusion, preventing cell entry Vaccines: induce protective antibody and T-cell responses against HA/NA antigens