Moloney murine leukemia virusGenetic VectorsRetroviridaeLeukemia Virus, MurineVirus IntegrationRNA-Directed DNA PolymeraseTransduction, GeneticVirion3T3 CellsGene Transfer TechniquesCell LineViral Envelope ProteinsBase SequenceVirus ReplicationMolecular Sequence DataDNA, ViralHIV-1Amino Acid Sequence