Revertants of rats cells transformed by avian erythroblastosis virus

Morphological revertants of the avian erythroblastosis virus (AEV)-transformed rat cell line ATla were isolated and characterised. The revertants are similar to the uninfected parental rat cell line in that they have regained an organized cytoskeleton and they are no longer capable of anchorage-independent growth. The pattern of integrated viral DNA in the revertants is indistinguishable from that of the transformed parent. However, the revertants do not express the integrated viral genome at either the mRNA or protein level. Phenotypic reversion thus is probably .due to reduced transcription of the AEV-transforming gene below a threshold necessary to induce morphological transformation.