GammaretrovirusRetroviridaeRetroviridae ProteinsXenotropic murine leukemia virus-related virusRetroviridae InfectionsSpumavirusTerminal Repeat SequencesPhascolarctidaeWhale, KillerLeukemia Virus, MurineEndogenous RetrovirusesRetroelementsDNA ContaminationTumor Virus InfectionsLeukemia Virus, FelineFatigue Syndrome, ChronicReceptors, VirusGene Products, envMolecular Sequence DataRetroviridae Proteins, OncogenicPhylogenyDNA, ViralProstatic NeoplasmsCell LineAmino Acid Sequence