Leukemia Virus, FelineLeukemia, FelineCat DiseasesCatsRetroviridae InfectionsSarcoma Viruses, FelineTumor Virus InfectionsFeline Acquired Immunodeficiency SyndromeImmunodeficiency Virus, FelineLynxProvirusesCanarypox virusLeukemia, ExperimentalRetroviridae Proteins, OncogenicViral Envelope ProteinsGenes, envTerminal Repeat SequencesReceptors, VirusAntigens, ViralThymus NeoplasmsDNA, ViralAntibodies, ViralRetroviridaeViral VaccinesHelper VirusesMolecular Sequence DataBase SequenceSpecific Pathogen-Free OrganismsGene Products, envRetroviridae ProteinsMinkLymphomaCell LineVaccines, InactivatedViremiaGenes, ViralLeukemiaViral ProteinsLymphoma, Non-HodgkinAmino Acid SequenceRecombination, GeneticProliferating Cell Nuclear AntigenRepetitive Sequences, Nucleic AcidNeutralization TestsPolymerase Chain ReactionRNA, ViralCloning, MolecularGene Products, gagSequence Homology, Nucleic AcidEnzyme-Linked Immunosorbent AssayVirus ReplicationBlotting, Southern