Rescue of viruses containing the cDNA-derived VP4 gene. (A) PAGE analysis of dsRNAs extracted from the rescued VP4 gene transfectants. Lane 1, dsRNAs from WT RRV; lane 2, dsRNAs from KU helper virus; lane 3, dsRNAs from KU-VP4(RRV). (B) PAGE analysis of dsRNAs extracted from single-gene reassortants. Lane 1, dsRNAs from WT RRV; lane 2, dsRNAs from strain TUCH; lane 3, dsRNAs from KU helper virus; lane 4, dsRNAs from KU-VP4(RRVR446G); lane 5, dsRNAs from RRVVP4-R446G.