Inhibition of Rauscher murine leukemia virus growth in vitro by actinomycin D

The growth of Rauscher murine leukemia virus was studied in vitro by measuring incorporation of uridine- 3H into purified virus. Labeled virus could be recovered from infected cell cultures 2 hours after adding the nucleoside precursor. Virus labeling was prevented by 0.5 μg of actinomycin D per milliliter, but not by inhibitors of cellular DNA synthesis. These results extend the similarities between the murine and avian RNA tumor viruses. 70 S viral RNA was prepared in good yield from purified labeled virus by exposure to 0.5% sodium dodecyl sulfate.