Bovine leukemia virus: an exogenous RNA oncogenic virus?

Short term cultures of bovine leukemic lymphocytes release virus particles with biochemical properties of RNA oncogenic viruses. These particles, tentatively called Bovine Leukemia Virus (BLV) have a high molecular weight-reverse transcriptase complex and a density averaging 1.155 g/ml in sucrose solutions. Molecular hybridizations between BLV-3H cDNA and several viral RNAs show that BLV is not related to Mason-Pfizer Monkey Virus (MPMV) Simian Sarcoma Associated Virus (SSV-1) Feline Leukemia Virus (FeLV) or Avian Myeloblastosis Virus (AMV). Rauscher Leukemia Virus (RLV) exhibits a slight but reproducible relatednesse to BLV. The high preference of BLV reverse transcriptase for Mg++ as the divalent cation suggests that BLV might be an atypical mammalian leukemogenic type C virus. Hybridization studies using BLV 3H cDNA as a probe suggest that the DNA of bovine leukemic cells contains viral sequences that cannot be detected in normal bovine DNA.