Terminal sialic acid residues (Sia)

Terminal sialic acid residues are nine-carbon acidic monosaccharides typically found at the outermost positions of glycan chains on the surface of host cell glycoproteins and glycolipids. These residues are essential for various biological processes, including cell-cell recognition, signal transduction, and the regulation of the immune system by acting as self markers that prevent autoimmune responses (Varki, 2008). However, they are also frequently utilized as attachment receptors by a wide range of pathogens, most notably the influenza virus, which uses its hemagglutinin protein to bind to specific sialic acid linkages (Schauer, 2009). In cancer, the upregulation of terminal sialic acids, or hypersialylation, facilitates tumor progression by promoting metastasis and allowing the tumor to evade immune detection through interactions with Siglec receptors on leukocytes (Bull et al., 2014). Therapeutic approaches include the use of inhaled recombinant sialidases, such as DAS181, which enzymatically remove these residues to prevent viral entry, as well as neuraminidase inhibitors that block the viral enzyme from cleaving these residues during the budding of new virions (Moss et al., 2012).

Other names

N-acetylneuraminic acidNeu5AcSialic acidsSialosidesGlycan-terminal sialic acidN-acetyl-neuraminate

Enzymatic cleavage of terminal sialic acid residues from host cell surfaces to prevent viral attachment; inhibition of viral neuraminidase to prevent the cleavage of sialic acid and release of viral progeny.