Early molecular events during the interaction of enveloped riboviruses with cells. II. A kinetic study.

A kinetic model was constructed and partly solved to describe the migration of the fluorescence label 1,6-diphenylhexatriene (DPH) in both directions when enveloped viruses, labelled with DPH in their envelopes are in contact with unlabelled cells or cell labelled in their membranes are in contact with unlabelled enveloped viruses. The central assumption is that two types of receptor sites exist on the cell surface, i.e., physical adsorption sites (P-sites), available to all the viruses studied in these papers and binding sites (B-sites) available only to the viruses which penetrate into the specific cells. The differential equations for the label migration, for different values of the ratio number of viruses number of sites were numerically solved, assuming different fractions of P- and B-sites. The equations also describe, appropriately the mechanism of rapid label migration in the system and substantiate the magnitude "time of residence" of the nonpenetrating viruses adsorbed on the cell surface. The resulting curves match satisfactorily those for the label release by the viruses and account well for the steady state values of the kinetics of label migration in the virus-cell system.