Evidence for helper-independent murine sarcoma virus: II. Differences between the ribonucleic acids of clone-purified leukemia virus, helper-independent and helper-dependent sarcoma viruses

Abstract

A clone of chronically infected transformed mouse cells produces a high titer (1 × 10 7 infectious units/ml) of helper-independent Moloney murine sarcoma virus [MuSV (R +T +]. In polyacrylamide gels the migration patterns of the native RNA from Moloney murine leukemia virus (MoMuLV) and MuSV (R +T +) were indistinguishable. However, denaturation and coelectrophoresis of the RNA from the two viruses revealed that the denatured RNA from MuSV (R +T +) migrated more slowly than the denatured RNA from MoMuLV. The difference was virtually identical to that described for Rous sarcoma-leukosis viruses. A second chronically infected, transformed clone produces a high titer (1 × 10 8 infectious units/ml) of helper-dependent MuSV (MuSV (R −T +)]. It also produces a low titer (1 × 10 4 infectious units/ml) of MuSV (R +T +). In polyacrylamide gels, the native RNA from MuSV (R −T +) had a faster rate of migration than did the native RNA from either MuSV (R +T +) or MoMuLV. On denaturation and coelectrophoresis the RNA of MuSV (R −T +) migrated with that of MuLV. The rate of migration of native RNA from cloned Moloney sarcoma-leukemia virus (MoMuSV (MuLV)) in polyacrylamide gels was identical with the native RNAs of cloned MoMuLV and MuSV (R +T +). In contrast, denaturation of the RNA from MoMuSV (MuLV) resulted in 2 populations of RNA; one of these comigrated with denatured RNA of MoMuLV, and the other with denatured RNA from MuSV (R +T +). The results obtained suggest that there are basic similarities in the organization and genetic behaviour of the RNA of avian and murine sarcoma-leukemia viruses.