Fig 4.

Infectivity of pRCAS-AP slippery sequence variants. (A) DF1 cells were transfected with pRCAS-WT or mutant derivatives (Transfection), and released virus was used subsequently to infect new cells (Infection) as detailed in Materials and Methods. Cell lysates (upper panels) and supernatant virus (lower panels) were analyzed by SDS-PAGE (8% and 15% gels, respectively) and Western blotting using a polyclonal anti-CA (p27) serum. (B) Duplicate dishes from the transfection illustrated in panel A were stained for alkaline phosphate activity. (C) Virus particles were harvested from 1 ml culture medium by ultracentrifugation, and reverse transcriptase activities were assayed. Incorporation of [α-³²P]dTTP was visualized by scintillation counting.