title: Control of reversion of Moloney virus sarcoma virus transformed cells.
abstract: Mouse cells transformed by the Moloney murine sarcoma virus (MSV) native to the species can give rise to revertants which are supersusceptible to a second cycle of transformation. The MSV retransformed cells can give rise to several complex functional states even after several cycles of cloning: a) Formation of sarcoma positive, leukemia negative (S+Lminus) type cells of which some sublines may be inducible for MSV by halogenated pyrimidines; b) detection of initially SminusLminus cells which spontaneously become transformed and S+Lminus; c) the derivation of flat murine leukemia virus positive (MuLV+) cells which have an atypical MuLV and may become MSV+ as well as MuLV+; d) the release of free MSV from some cell clones with an apparent absence of MuLV. A general feature of all the above variants is a failure of detection of spontaneous reversion occurring after the second cycle of transformation. The nature of MuLV spontaneously released is that of a poorly replicating MuLV which exhibits cross-interference with other MuLV pseudotypes of MSV and the envelope which is most similar to that of Moloney leukemia virus (MLV). The examination for spontaneous reversion in human S+Lminus cells transformed by the same type of genome capable of good frequency of reversion in mouse cells, did not yield human revertant cells.
mesh_terms: D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D017988:Gammaretrovirus / Q000254:growth & development*; D006378:Helper Viruses / Q000254:growth & development; D008979:Moloney murine leukemia virus / Q000254:growth & development*; D009053:Sarcoma Viruses, Murine / Q000254:growth & development*; D014779:Virus Replication