Neuraminidase (H9N2 avian influenza virus) (NA)

The H9N2 avian influenza virus neuraminidase (NA) is a tetrameric surface glycoprotein that functions as an enzyme essential for the viral replication cycle. Its primary role is to catalyze the hydrolysis of terminal sialic acid residues from host cell receptors and newly synthesized viral glycoproteins, a process that prevents the aggregation of progeny virions and facilitates their release from the infected cell surface (UniProt: Q9WJT5). Furthermore, the enzyme enables the virus to penetrate the sialic acid-rich mucus layers of the respiratory tract to reach and infect target epithelial cells (PubMed: 22675204). Because H9N2 viruses are endemic in poultry and possess significant zoonotic potential, NA serves as a critical target for antiviral drugs such as oseltamivir and zanamivir, which occupy the highly conserved active site of the enzyme (PubChem: CID 65028). However, the therapeutic utility of these drugs is often challenged by the emergence of specific amino acid substitutions in the N2 neuraminidase, such as R292K or E119V, which can significantly reduce drug susceptibility (PubMed: 30107931, NIH). Understanding the structure and evolution of H9N2 neuraminidase is vital for both clinical management of human cases and global pandemic preparedness.

Other names

SialidaseExo-alpha-sialidaseN2 neuraminidaseAcylneuraminyl hydrolase

Neuraminidase inhibitor that prevents the enzyme from cleaving sialic acid residues, thereby trapping progeny virions on the host cell surface and inhibiting the spread of infection.