Several Classes of Retroviruses Are Produced by an AKR Mouse T Lymphoma Cell Line

Abstract

SUMMARYCharacterization of the viruses produced by the spontaneous T lymphoma cell line SL3 is presented. Using supernatant fluids or direct co-cultivation of cells, the SL3 cell line was found to produce replication-defective viruses in excess of replicationcompetent viruses. The replication-competent viruses released were predominantly those negative in the XC plaque assay (XC-); XC + viruses represented a minor population. However, when the SL3-derived viruses were passed in mouse embryo fibroblasts, XC-viruses were rarely recovered, and XC + viruses were readily isolated. These viruses were all ecotropic and lymphomagenic. Viruses with dual host range and nononcogenic ecotropic viruses were not isolated from the lymphoma cells. Two replication-defective viruses from SL3 cells were studied. Both could be rescued by non-oncogenic retroviruses and were then lymphomagenic. One defective virus appeared related to XC + viruses. In these studies, the XC ÷ and XC-viruses appeared to represent two different interference classes using separate cell receptors. Taken together, these experiments show that the SL3 T lymphoma cells replicate a variety of viruses most of which are lymphomagenic. Virus replication and/or virus integration may be the means of maintaining the malignant phenotype of these T lymphoma cells.