Influenza A virus surface glycoproteins (Hemagglutinin and Neuraminidase) (HA/NA)

Influenza A virus surface glycoproteins, specifically Hemagglutinin (HA) and Neuraminidase (NA), are the primary structural proteins on the viral envelope that facilitate the infection cycle (Gamblin & Skehel, 2010, J Biol Chem). Hemagglutinin functions as a viral attachment protein by binding to sialic acid receptors on host respiratory epithelial cells and subsequently mediating membrane fusion within endosomes (UniProt P03435). Neuraminidase acts as an enzyme that removes sialic acid residues from host cell surfaces and progeny virions, preventing viral clumping and enabling the release of new virus particles (UniProt P03468). These glycoproteins are the major antigens recognized by the host immune system and are the primary components of seasonal influenza vaccines (NIH/NIAID). Therapeutic intervention typically involves Neuraminidase inhibitors, such as oseltamivir and zanamivir, which arrest the spread of the virus by preventing viral egress (von Itzstein, 2007, Nat Rev Drug Discov). Additionally, inhibitors targeting the fusion activity of Hemagglutinin, such as umifenovir, are utilized to block the early stages of viral entry (Blaising et al., 2014, Antiviral Res). Continuous monitoring of these proteins is essential due to antigenic drift and shift, which can lead to reduced vaccine efficacy and the emergence of drug-resistant strains (StatPearls, Influenza).

Other names

Hemagglutinin and NeuraminidaseViral surface antigensFlu surface proteinsHA/NAInfluenza A virus HAInfluenza A virus NA

Neuraminidase inhibitors prevent the enzymatic cleavage of sialic acid, which traps newly formed virions at the host cell membrane and prevents further infection of adjacent cells (von Itzstein, 2007, Nat Rev Drug Discov). Hemagglutinin inhibitors or binders prevent the virus from attaching to host receptors or inhibit the conformational change necessary for the fusion of the viral envelope with the host cell membrane (Blaising et al., 2014, Antiviral Res).