MOLONEY MURINE SARCOMA VIRIONS SYNTHESIZE FULL-GENOME-LENGTH DOUBLE-STRANDED DNA INVITRO

Moloney sarcoma virus (MSV) virions incubated under optimal conditions were shown to support extensive synthesis of double-stranded DNA. The major product, a 5950-base-pair(6-kilobase-pair DNA) double-stranded DNA, was characterized by cleavage with restriction endonucleases and shown to contain a 600-nucleotide-long direct repeat at both ends of MSV genome. Linear DNA molecules made in vivo shortly after infection were compared to the linear double-stranded DNA synthesized in vitro. The restriction maps of both viral DNA products were indistinguishable. The 600-base-pair repeat results in a progeny DNA molecule that is longer than the parental MSV genomic RNA. The generation of this repeat must involve a mechanism that allows the viral reverse transcriptase (RNA-dependent DNA nucleotidyltransferase) to copy 5'-and 3'-terminal genomic (+) strand sequences twice.