N-acetylneuraminic acid (Sialic acid) (Neu5Ac)

Sialic acid residues, primarily N-acetylneuraminic acid (Neu5Ac), are terminal sugar molecules found on the glycan chains of glycoproteins and glycolipids on the surface of human respiratory epithelial cells (Varki A, 2008). These residues serve as critical attachment points for various pathogens, most notably the influenza virus, which utilizes its hemagglutinin protein to bind to specific sialic acid linkages. Specifically, alpha-2,6 linkages are predominant in the human upper respiratory tract, while alpha-2,3 linkages are more common in the lower respiratory tract and avian species (Shinya K, et al., 2006; Nicholls JM, et al., 2007). Beyond viral entry, sialic acids play essential roles in cell-cell recognition, immune system modulation, and maintaining the structural integrity of the mucus layer. In pharmacology, sialic acids are the substrate for the viral enzyme neuraminidase; drugs like oseltamivir inhibit this enzyme to prevent the release of new viral particles from infected cells. Additionally, therapeutic strategies like DAS181 (Fludase) involve the direct enzymatic removal of these residues from the host cell surface to block viral infection (Moss RB, et al., 2011).

Other names

N-acetylneuraminic acidNeu5AcSialic acid receptorSiaNeuraminic acidAlpha-2,6-linked sialic acidAlpha-2,3-linked sialic acid

Neuraminidase inhibition (prevents viral release by blocking the cleavage of sialic acid) and Sialidase activity (enzymatic removal of sialic acid residues to prevent viral entry).