Transfection with the proviral DNA of a type D retrovirus (Mason-Pfizer monkey virus)

Chromosomal DNA was isolated from CMMT cells which were producing Mason-Pfizer monkey virus (M-PMV), a type D simian retrovirus. Human embryonic cells were transfected with the DNA. About 2 weeks after transfection, 3 of 7 culture dishes began to produce M-PMV which could be detected by virus-mediated cell fusion in RSb human cells dually transformed by Rous sarcoma virus and simian virus 40, reverse transcriptase assay, and electron microscopy. Mock-transfected cultures did not produce virus.