Hemagglutinin and neuraminidase (from Influenza A and B viruses) (HA and NA)

Hemagglutinin and neuraminidase are the two major glycoproteins found on the surface of Influenza A and B viruses, playing central roles in viral infectivity. Hemagglutinin (HA) is a trimeric viral envelope glycoprotein responsible for binding sialic acid on host cell surfaces, mediating viral attachment and membrane fusion to initiate infection[3][4]. Neuraminidase (NA) is a tetrameric viral surface enzyme that cleaves terminal sialic acid residues from glycoproteins, enabling the release of progeny virions from infected cells and preventing viral aggregation[1][2]. The functional balance between HA (receptor binding) and NA (receptor cleavage) is essential for viral fitness, pathogenicity, and transmission. Both are targets for antiviral drugs and the primary antigens for neutralizing antibodies, making them critical for vaccine design and antiviral therapy[1][5]. Resistance, antigenic drift, and shift are ongoing concerns for both targets[1][2].

Other names

Influenza hemagglutininInfluenza neuraminidaseHANA

NA inhibitors block neuraminidase enzymatic activity to prevent release of new viral particles[1] HA-directed antibodies block receptor binding, prevent membrane fusion, or neutralize the virus[5]