Alpha-2,3-linked sialic acid receptor (alpha-2,3-SA receptor) (alpha-2,3-SA receptor)

Alpha-2,3-linked sialic acid receptors are terminal glycan structures on the surface of avian respiratory epithelial cells that serve as the primary docking site for avian influenza viruses (Shinya et al., 2006, Nature). These receptors are characterized by a sialic acid residue, typically N-acetylneuraminic acid, connected to a galactose residue via an alpha-2,3 glycosidic linkage (Nicholls et al., 2007, Lancet). This specific linkage is the key determinant of the host tropism of avian influenza viruses, such as H5N1 and H7N9, which preferentially bind to these structures over the alpha-2,6 linkages found in the human upper respiratory tract (Van Riel et al., 2006, Science). In the context of disease, these receptors facilitate the attachment of the viral hemagglutinin protein, leading to endocytosis and subsequent viral replication within the host cell. Because these receptors are essential for the initial stages of infection, they are a significant target for antiviral drug development. One therapeutic approach involves the use of recombinant sialidases, like DAS181 (Fludase), which enzymatically remove the sialic acid residues from the respiratory epithelium, thereby stripping the virus of its binding sites (Malakhov et al., 2006, Antimicrob Agents Chemother). Additionally, the viral neuraminidase enzyme targets these same receptors to facilitate the release of progeny virions from infected cells, a process inhibited by drugs like oseltamivir (Gubareva et al., 2000, Lancet). Monitoring the distribution and density of these receptors in different species helps researchers predict the zoonotic potential of emerging influenza strains.

Other names

Avian influenza virus receptorNeu5Ac-alpha-2,3-Galalpha-2,3-sialylglycanalpha-2,3-linked sialic acidAvian-type influenza receptor

DAS181 (Fludase) is a recombinant fusion protein containing a sialidase catalytic domain that enzymatically removes terminal alpha-2,3-linked and alpha-2,6-linked sialic acid residues from the surface of respiratory epithelial cells, thereby eliminating the binding sites for influenza viruses and preventing infection (Malakhov et al., 2006). Neuraminidase inhibitors like oseltamivir and zanamivir target the viral neuraminidase enzyme to prevent it from cleaving these same sialic acid receptors, which is a necessary step for the release of newly formed viral particles from the host cell (Gubareva et al., 2000).