Sendai virus binds to a dispersed population of NBD-GD1a.

Receptor aggregation is believed to be an important step in the attachment of membrane enveloped virus' to target cell membranes. A likely receptor for Sendai virus is the ganglioside GD1a. In this work we have studied the membrane diffusion of the fluorescent ganglioside NBD-GD1a on the surface of CV-1 cells with standard photobleaching techniques. Using confocal laser scanning microscopy (CLSM) and Image Correlation Spectroscopy (ICS) NBD-GD1a is shown to exist in at least two populations: dispersed and aggregated. By quantifying the distribution of NBD-GD1a pre- and post-incubation with Sendai virus it is shown that the virus induces a dose-dependent clustering of NBD-GD1a. Image cross-correlation spectroscopy (ICCS) is used to further quantitatively characterize this clustering by demonstrating that it occurs due to binding of virus to the dispersed population of NBD-GD1a.