RNA composition of Junin virus.

Junin virus grown in BHK-21 cells was labeled with [3H]uridine and highly purified by differential and isopycnic centrifugation. The RNAs extracted with phenol and analyzed by polyacrylamide gel electrophoresis were shown to be composed of four large species (33, 28, and 18S) and three small ones (4, 5, and 5.5S). This pattern was similar to ones already reported for other arenaviruses. However, there was a striking difference when the virus labeling was performed in the presence of actinomycin D. Labeling of viral rRNA was as much as 60% of the levels obtained in the absence of the drug under conditions in which cellular rRNA's were inhibited by 95% or more.