Influenza A virus (H1N1) 2009 pandemic hemagglutinin and neuraminidase (2009 H1N1 HA/NA)

The 2009 H1N1 influenza virus hemagglutinin (HA) and neuraminidase (NA) are the primary surface glycoproteins of the pandemic A/California/04/2009 (H1N1) strain (CDC, 2009). Hemagglutinin is a class I fusion protein that mediates viral attachment to host cell sialic acids and subsequent membrane fusion in the endosome (UniProt C3W5X2). Neuraminidase is a glycoside hydrolase that removes sialic acid from viral and cellular surfaces, preventing the aggregation of progeny virions and facilitating their release from infected cells (UniProt C3W5X3). These proteins are the critical components of influenza vaccines, which aim to induce neutralizing antibodies that block HA-mediated entry or NA-mediated release (NIH, 2023). Neuraminidase is also the specific target for antiviral drugs such as oseltamivir and zanamivir, which competitively inhibit the enzyme active site (PubChem, 2024). The designation No direct molecular target in pharmacological databases like ChEMBL typically indicates that the therapeutic agent, such as a vaccine, is directed against the whole viral assembly or multiple surface antigens rather than a single host protein (ChEMBL, 2024). Monitoring these targets is essential due to the risk of antigenic drift and the emergence of resistance mutations, such as the H275Y substitution in neuraminidase (PubMed, 2011).

Other names

2009 H1N1 surface glycoproteinsA/California/04/2009 HA/NASwine flu HA and NAH1N1pdm09 HA/NANo direct molecular target 2009 HA/NA)

Neuraminidase inhibition to prevent viral release and antibody-mediated neutralization of hemagglutinin to block viral entry.