Time course of treatment of cells with nocodazole. Medium containing 10 μg/mL nocodazole was added to the cells at the indicated time points relative to infection and maintained for the entire duration of the 72 h incubation. Control cells were incubated with medium containing the equivalent amount of the solvent DMSO. Infectious virus (a) and viral antigen (b) were measured. The closed circles represent the drug and the open circles the DMSO control.