Fixation of Oligosaccharides to a Surface May Increase the Susceptibility to Human Parainfluenza Virus 1, 2, or 3 Hemagglutinin-Neuraminidase

Abstract

The hemagglutinin-neuraminidase (HN) protein of human parainfluenza viruses (hPIVs) both binds (H) and cleaves (N) oligosaccharides that containIn the present study, we tested the binding specificity of hPIV2 on the Consortium for Functional Glycomics' glycan array and found that hPIV2 binds to oligosaccharides containing the same motif. We determined the specificities of N on red blood cells, soluble smallmolecule and glycoprotein substrates, and the glycan array and compared them to the specificities of H. hPIV2 and -3, but not hPIV1, cleaved their ligands on red blood cells. hPIV1, -2, and -3 cleaved their NeuAc␣2-3 ligands on the glycan array; hPIV2 and -3 also cleaved NeuAc␣2-6 ligands bound by influenza A virus. While all three HNs exhibited similar affinities for all cleavable soluble substrates, their activities were 5-to 10-fold higher on small molecules than on glycoproteins. In addition, some soluble glycoproteins were not cleaved, despite containing oligosaccharides that were cleaved on the glycan array. We conclude that the susceptibility of an oligosaccharide substrate to N increases when the substrate is fixed to a surface. These findings suggest that HN may undergo a conformational change that activates N upon receptor binding at a cell surface.

Quantitative Comparison of Human Parainfluenza Virus Hemagglutinin-Neuraminidase Receptor Binding and Receptor Cleavage

“…Identical glycans are more susceptible to N when fixed to a surface (e.g., attached to a glycan array or glycoprotein or lipid on an RBC membrane) than when attached to a glycoprotein in solution. Our findings suggest that N can be activated by interaction with substrate on a surface, perhaps through a conformational change in the HN protein (7).…”

“…hPIVs bind to structures containing the motif Neu5Ac␣2-3Gal␤1-4GlcNAc on a glycan array or on a thin-layer chromatography plate spotted with gangliosides (5,6). hPIV type 1 (hPIV1) and hPIV2 tolerate modifications to the motif, including sulfation of Gal, fucosylation of GlcNAc (sialylLewis x ), and extension with additional lactosamines or branched glycan structures, while hPIV3 requires at least one extra Gal for binding and tolerates fucosylation but not sulfation or branching (5,7). Binding may be limited to motifs on N-glycans or glycolipids, because inhibition of glycolipid formation or N-glycosylation renders COS-7 cells resistant to Newcastle disease virus (NDV) infection, while inhibitors of O-glycosylation do not (8).…”

Rapid Fluorescent Detection Assay for Human Parainfluenza Viruses

“…Ca 2+ ion was previously reported to boost hPIV1 sialidase activity. 19,21,22) Both dot-blotted hPIV1 and hPIV3 were fluorescently visualized in a manner dependent on the amount of hPIV under UV irradiation. At least 2 −4 HAU for hPIV1 and 2° HAU for hPIV3 were distinctly detected by incubation of 10 µM BTP3-Neu5Ac for 10 min (Fig.…”

Individual N-Glycans Added at Intervals along the Stalk of the Nipah Virus G Protein Prevent Fusion but Do Not Block the Interaction with the Homologous F Protein

“…The receptor binding activity of the chimera was assayed by its ability to adsorb guinea pig erythrocytes (Bio-Link Laboratories, Liverpool, NY) (23). The NA activity of the chimera was determined with 2-(4-methylumbelliferyl)-␣-D-N-acetylneuraminic acid (MUN) as the substrate, as described by Tappert et al (38).…”