Avian LeukosisAvian leukosis virusAlpharetrovirusChickensBursa of FabriciusAvian ProteinsAvian Sarcoma VirusesChick EmbryoEnzootic Bovine LeukosisPoultry DiseasesReticuloendotheliosis virusSarcoma, AvianReceptors, VirusQuailCoturnixGenes, polMarek DiseaseProvirusesGenes, envHemangiomaDNA, ViralLymphomaHerpesvirus 2, GallidHistiocytic SarcomaGenes, gagAvian myeloblastosis virusHelper VirusesRepetitive Sequences, Nucleic AcidBase SequenceGenes, ViralCulture TechniquesMolecular Sequence DataDefective VirusesOncogenesRNA, ViralEndogenous RetrovirusesRNA-Directed DNA PolymeraseTenosynovitisCell LineViral InterferenceVirus ReplicationRetroviridaeRecombination, GeneticLeukemia Virus, BovineVirus IntegrationCell Transformation, ViralRetroviridae ProteinsBirdsViral Envelope ProteinsFibroblastsCell Transformation, NeoplasticCytopathogenic Effect, ViralGenetic VectorsAmino Acid SequenceSpecies SpecificityNucleic Acid HybridizationAntigens, ViralCloning, MolecularGenome, Viral