Glycobiology Advance Access originally published online on July 22, 2009
Glycobiology 2009 19(11):1176-1184; doi:10.1093/glycob/cwp103
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QCM-D studies of human norovirus VLPs binding to glycosphingolipids in supported lipid bilayers reveal strain-specific characteristics
2 Department of Clinical Chemistry and Transfusion Medicine, Sahlgrenska University Hospital
3 Department of Applied Physics, Chalmers University of Technology, Gothenburg, Sweden
1 To whom correspondence should be addressed: Tel: +46-31-342-1330; Fax: +46-31-828458; e-mail: goran.larson{at}clinchem.gu.se
Received on April 3, 2009; revised on July 9, 2009; accepted on July 9, 2009
Susceptibility to norovirus infection has been linked to secretor status. Norovirus virus-like particles (VLPs; 0– 20 µg/mL) from the Norwalk (GI.1) and Dijon (GII.4) strains were assayed for binding to H type 1 and Lewis a pentaglycosylceramides, incorporated in laterally fluid supported lipid bilayers. Binding kinetics was monitored in real time in 40 µL stationary reaction chambers, using quartz crystal microbalance with dissipation (QCM-D) monitoring. Both strains displayed binding only to H type 1 and not to Lewis a glycosphingolipids, typical for epithelial cells of susceptible and resistant individuals, respectively. This binding specificity was confirmed by VLPs binding to the two glycosphingolipids chromatographed on TLC-plates. Experiments using bilayers with mixtures of H type 1 and Lewis a, with the total glycosphingolipid concentration constant at 10 wt%, showed that binding was only dependent on H type 1 concentrations and identical to experiments without additional Lewis a. Both strains showed a threshold concentration of H type 1 below which no binding was observable. The threshold was one order of magnitude higher for the Dijon strain (2 wt% versus 0.25 wt%) demonstrating that the interaction with a significantly larger number of glycosphingolipids was needed for the binding of the Dijon strain. The difference in threshold glycosphingolipid concentrations for the two strains suggests a lower affinity for the glycosphingolipid for the Dijon compared to the Norwalk strain. We propose that VLPs initially bind only a few glycosphingolipids but the binding is subsequently strengthened by lateral diffusion of additional glycosphingolipids moving into the interaction area.
Key words: glycosphingolipid / H type 1 / norovirus / QCM-D / supported lipid bilayer