FIG. 6.
Equilibrium density centrifugation of extracellular virus. RK13 cells were infected with I-B5R−, I-B5Rrescue, and I-B5RΔSCR1–4 labeled with [35S]methionine and [35S]cysteine, and supernatant media was subjected to centrifugation in CsCl gradients. Fractions were collected from the bottom of tubes, and the levels of radioactivity of aliquots were counted in a liquid scintillation spectrometer. The densities of selected fractions were determined. Peak counts shown correspond to the characteristic density of EEV.