Alpha-2,3-linked sialic acid (α2,3-Sia)

Alpha-2,3-linked sialic acid residues are terminal carbohydrate structures found on the glycans of cell-surface glycoproteins and glycolipids. These residues consist of N-acetylneuraminic acid (Neu5Ac) attached to a galactose unit via an alpha-glycosidic bond at the 2 and 3 positions. In human physiology, these linkages are predominantly expressed in the lower respiratory tract, specifically on type II pneumocytes in the alveoli, and serve as the primary attachment point for avian influenza viruses such as H5N1 and H7N9 (Shinya et al., 2006, Nature). Beyond viral entry, they facilitate the adherence of various bacterial pathogens, including Streptococcus pneumoniae, and play roles in cell-cell adhesion and immune system modulation (Varki, 2008, Trends in Molecular Medicine). Therapeutic interventions targeting these residues include the sialidase DAS181 (Fludase), which enzymatically strips the sialic acids to prevent viral infection, and neuraminidase inhibitors that block the viral enzyme responsible for cleaving these linkages during viral egress (Triana-Baltzer et al., 2009, Antimicrobial Agents and Chemotherapy). Monitoring the density and distribution of these residues is essential for understanding viral tropism and the risk of zoonotic transmission to humans (Nicholls et al., 2007, Nature Medicine). Additionally, aberrant expression of these sialic acids is often observed in various cancers, where they contribute to tumor cell invasion and evasion of the immune response.

Other names

Neu5Acα2-3GalAvian influenza receptorα2,3-sialylglycanα2,3-Neu5AcSialic acid alpha-2,3-galactose

Enzymatic cleavage of terminal alpha-2,3-linked sialic acid residues from the host cell surface to prevent viral attachment and entry; or inhibition of viral neuraminidase to prevent the cleavage of these residues, thereby trapping budding virions on the host cell surface.