Hemagglutinin (HA) and Neuraminidase (NA) (HA/NA)

The term "Influenza virus hemagglutinin-neuraminidase protein" is a misnomer, as influenza viruses (Orthomyxoviridae) utilize two distinct surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), to facilitate their life cycle [1, 2, 6]. Hemagglutinin is a trimeric protein responsible for binding the virus to sialic acid receptors on host cells and mediating the fusion of the viral envelope with the host cell membrane [3, 9, 12]. Neuraminidase is a tetrameric enzyme that cleaves sialic acid residues, allowing newly formed virions to be released from the host cell and preventing viral aggregation [1, 5, 8]. These proteins are the primary targets for the host immune system and are the focus of annual vaccine development [4, 7, 9]. Pharmacological interventions include neuraminidase inhibitors like oseltamivir and zanamivir, which block viral spread, and hemagglutinin inhibitors like umifenovir, which prevent viral entry [1, 3, 4]. The high rate of mutation in these proteins, known as antigenic drift and shift, presents a significant challenge for long-term therapeutic efficacy and necessitates continuous monitoring of circulating strains [1, 5, 12].

Other names

Hemagglutinin (HA)Neuraminidase (NA)Surface glycoproteinsHA/NA complexHemagglutinin-neuraminidase (misnomer)

Neuraminidase inhibition prevents the release of progeny virions from infected cells; hemagglutinin inhibition prevents viral attachment and membrane fusion.