Analysis of murine leukemia virus-related RNAs in uninfected and infected mouse cells

RNAs were extracted from various cytoplasmic fractions of both uninfected and infected mouse cell cultures using established procedures. These RNAs were analyzed by agarose gel electrophoresis, diazobenzyloxymethyl-paper transfer, and molecular hybridization using copy DNAs to both the total murine leukemia virus 70S RNA and the 3' portion of the 35S virus RNA. This newly established method of RNA analysis was from 10 to l00 more sensitive than those techniques previously used in the study of RNA tumor virus-related RNAs in uninfected and infected mouse cells.

Using these techniques, I have found that only 35S virus-specific RNA was detected in the polyribosomes of mouse cells early after infection by murine leukemia viruses. This conflicted with the data of Shurtz et al. (1979) which indicated the presence of a second virus-specific RNA of 24S sizes. I have also shown that the newly transcribed virus-specific RNAs which were associted with the polyribosomes of these infected mouse cells included 35S, 30S, and 24S RNAs. I have also demonstrated that several uninfected mouse cell cultures, the NIH3T3 cell line and C57BL/6 cell line, contained endogenously transcribed murine leukemia virus-related RNAs. It was found that these RNAs were polyadenylated and were associated primarily with cellular polyribosomes.