H5N1 chicken influenza viruses display a high binding affinity for Neu5Acα2-3Galβ1-4(6-HSO3)GlcNAc-containing receptors

To characterize differences in the receptor-binding specificity of HSNI chicken viruses and viruses of aquatic birds, we used a panel of synthetic polyacrylamide (PAA)-based sialylglycopolymers that carried identical terminal NeuSAca2-3Gal fragments but varied by the structure of the next saccharide residues. A majority of duck viruses irrespective of their HA subtype, bound with the highest affinity to trisaccharide NeuSAca2-3Gal~ 1-3GlcNAc, suggesting that these viruses preferentially recognize sialyloligosaccharide receptors with type I core (Gal~ 1-3GlcNAc). Substitution of 6-hydroxyl group of GlcNAc residue of tested sialylglycopolymers by 6-sulfo group had little effect on receptor binding by duck viruses. By contrast, HSN I chicken and human viruses isolated in 1997 in Hong Kong preferred receptors with type 2 core (Gal~I-4GlcNAc~) and bound sulfated trisaccharide NeuSAca2-3Gal~I-4(6-HSO3)GlcNAc~ (6-Su-3'SLN) with the extraordinary high affinity. Another chicken virus, A/FPV/Rostok/34 (H7NI), and several mammalian viruses also displayed an increased affinity for sulfated sialyloligosaccharide receptor. The binding of chicken and mammalian viruses to tracheal epithelial cells of green monkey decreased after treatment of cells with glucosamine-6-sulfatase suggesting the presence of 6-0-Su-3' SLN determinants in the airway epithelium. It remains to be seen whether existence of the 6-0-Su-3'SLN groups in the human airway epithelial cells might facilitate infection of humans with HSN I chicken viruses.