FIG. 7.

Multiple-step growth with WT rSV5-GFP and rSV5-P/V-CPI−. (A) Fluorescence microscopy assay for virus spread. A549 cells were mock infected or infected at an MOI of 0.05 with rSV5-GFP or rSV5-P/V-CPI−. At 24 or 48 h p.i., the cells were fixed with 2% PFA and then analyzed by microscopy for GFP fluorescence. Phase-contrast microscopy is shown in the left panels, and GFP fluorescence is shown in the right panels. (B) Multiple-step growth assay. A549 cells were infected with rSV5-GFP or rSV5-P/V-CPI− at an MOI of 0.05. Medium was harvested at the indicated times postinfection, and the viral titer was determined by a plaque assay on CV-1 cells.