FIG. 7.

Phenotypes of SIN43-derived viruses containing single or double adaptive mutations in genomes. (A) Single-step viral growth curves after electroporation of 1 μg of in vitro-synthesized RNAs into C₇10 cells. At the indicated times, the medium was replaced and virus titers were determined in C₇10 cells, as described in Materials and Methods. Protein synthesis (B) and viral RNA replication (C) are shown for C₇10 cells transfected with 1 μg of the RNAs. At 18.5 h posttransfection, the cells were labeled with [³⁵S]methionine and analyzed in a sodium dodecyl sulfate-10% polyacrylamide gel as described in Materials and Methods. For RNA analysis, at 18.5 h posttransfection, the medium in other wells was replaced with 1 ml of alpha MEM supplemented with 10% FBS, dactinomycin (1 μg/ml), and [³H]uridine (20 μCi/ml). After 3 h of incubation at 30°C, RNAs were isolated from the cells and analyzed by agarose gel electrophoresis as described in Materials and Methods.