Neuraminidase N9 (Influenza A virus) (NA)

Neuraminidase N9 is a critical surface glycoprotein of the H7N9 avian influenza virus, an orthomyxovirus that emerged as a significant human pathogen in 2013. It functions as a sialidase enzyme (EC 3.2.1.18) that catalyzes the removal of terminal sialic acid residues from host cell surface receptors and viral hemagglutinin [UniProt: P0C6Y6]. This enzymatic activity is essential for the release of newly synthesized progeny virions from the host cell membrane and prevents the clumping of viral particles, thereby facilitating the spread of the virus throughout the respiratory tract [PubMed: 23676222]. In the context of human infection, H7N9 has caused severe respiratory illness with high mortality rates, making its neuraminidase a primary target for antiviral therapy [CDC: H7N9]. N9 neuraminidase is inhibited by the neuraminidase inhibitor (NAI) class of drugs, such as oseltamivir and zanamivir, which act as transition-state analogs to block the enzyme's active site [PubMed: 24046371]. However, the clinical management of H7N9 is complicated by the rapid emergence of resistance-conferring mutations, most notably the R292K substitution, which significantly reduces the efficacy of several existing inhibitors [PubMed: 23754667].

Other names

SialidaseExo-alpha-sialidaseNAN9 subtype neuraminidaseH7N9 NA

Inhibition of the neuraminidase enzyme prevents the cleavage of terminal sialic acid residues from host cell receptors, thereby trapping progeny virions on the cell surface and preventing the spread of infection.