Influenza neuraminidase (NA)

Influenza neuraminidase (NA) is a tetrameric glycoprotein found on the surface of influenza A and B viruses, including those specifically selected for seasonal vaccines such as H1N1, H3N2, and Influenza B lineages (UniProt P03468; CDC, 2023). It functions as an enzyme that cleaves terminal sialic acid residues from glycoproteins and glycolipids, a process essential for the release of progeny virions from infected host cells and for preventing viral aggregation (Gamblin & Skehel, 2010). By removing sialic acid from the respiratory tract mucus, NA also facilitates the movement of the virus through the airway to reach target epithelial cells (McAuley et al., 2019). In the context of vaccines, NA is a key antigenic component, and antibodies against it can reduce disease severity and viral shedding by inhibiting this enzymatic activity (PubMed PMC4841495). It is the primary target for the class of antiviral drugs known as neuraminidase inhibitors, such as oseltamivir and zanamivir (StatPearls, 2023). These drugs mimic the transition state of sialic acid cleavage to competitively inhibit the enzyme's active site (PubChem CID 65028). Monitoring the neuraminidase of vaccine-included strains is critical for assessing vaccine efficacy and detecting the emergence of drug-resistant variants like the H275Y mutation (WHO, 2022).

Other names

SialidaseExo-alpha-sialidaseNeuraminidaseViral neuraminidaseNA protein

Competitive inhibition of the neuraminidase enzyme, which prevents the cleavage of terminal sialic acid residues on host cell receptors and viral glycoproteins, thereby trapping progeny virions at the cell surface and halting the spread of infection (StatPearls, 2023).