GammaretrovirusXenotropic murine leukemia virus-related virusRetroviridae InfectionsPhascolarctidaeWhale, KillerLeukemia Virus, MurineEndogenous RetrovirusesDNA ContaminationTumor Virus InfectionsLeukemia Virus, FelineFatigue Syndrome, ChronicTerminal Repeat SequencesReceptors, VirusGene Products, envMolecular Sequence DataPhylogenyDNA, ViralProstatic NeoplasmsCell LineAmino Acid Sequence