Influenza hemagglutinin and neuraminidase protein (HA and NA)

Influenza hemagglutinin and neuraminidase proteins are two major glycoproteins found on the surface of influenza viruses and are key determinants of both infectivity and immune recognition. Hemagglutinin (HA) mediates the initial binding of the virus to host cell surface sialic acid residues and drives the fusion of viral and host membranes, enabling viral entry[1][3][10]. Neuraminidase (NA) is an exosialidase enzyme that cleaves sialic acid residues from host and viral glycoproteins, promoting the release of new viral particles from infected cells and helping prevent virion aggregation[3][4][7][9]. The balance of HA and NA activity is crucial for efficient viral replication and transmission. Both proteins are highly variable and are the primary antigens responsible for seasonal and pandemic influenza outbreaks; as such, they are the principal targets of vaccines and several antiviral drugs. Neutralizing antibodies to HA can block viral entry, while neuraminidase inhibitors (such as oseltamivir and zanamivir) prevent viral release[3][4][7]. Frequent mutations in the antigenic regions of these proteins necessitate continuous surveillance and regular updating of vaccines to maintain efficacy.

Other names

Influenza HAInfluenza NAInfluenza A hemagglutininInfluenza A neuraminidaseInfluenza surface glycoproteins

Drugs targeting influenza hemagglutinin and neuraminidase act by blocking viral attachment to sialic acid–containing host receptors (by anti-HA antibodies), inhibiting viral membrane fusion (by targeting HA conformational changes), or by inhibiting neuraminidase enzymatic activity to prevent virion release and spread (by small molecules such as oseltamivir, zanamivir, etc.).