ProvirusesEndogenous RetrovirusesLeukemia Virus, MurineDNA, ViralVirus IntegrationRetroviridaeGenes, ViralAKR murine leukemia virusMammary Tumor Virus, MouseTerminal Repeat SequencesBase SequenceMice, Inbred AKRRepetitive Sequences, Nucleic AcidReticuloendotheliosis virusMoloney murine leukemia virusRecombination, GeneticRetroviridae InfectionsAvian leukosis virusLeukemia Virus, FelineDNA Restriction EnzymesDefective VirusesHelper VirusesMolecular Sequence DataLeukemia, ExperimentalGenes, envGenes, polMink Cell Focus-Inducing VirusesAvian LeukosisMice, Inbred StrainsGenes, gagThymus NeoplasmsCloning, MolecularLymphomaNucleic Acid HybridizationVirus ReplicationRNA, Viral