Distribution of Mason-Pfizer virus-specific sequences in the DNA of primates.

Iodinated Mason-Pfizer virus (MPV) 60-70S RNA has been used in molecular hybridization experiments to determine the distribution of MPV-specific proviral sequences in the DNAs of primates. Approximately 20% of the MPV genome is present as endogenous provirus in rhesus monkeys. Competitive hybridization experiments showed no homology between MPV 60-70S RNA and the 60-70S RNAs of M7, RD-114, and the simian sarcoma virus. No MPV-specific proviral sequences were detected in the DNAs of apparently normal tissues of various species of New World monkeys, apes, and humans. The part of the MPV genome that is endogenous to rhesus is also endogenous to the other species of Old World monkeys examined: baboon, African green, and patas. This was determined as a result of the following observations: (i) C(0)t(1/2) values and final extent of hybridization were the same for all four species. (ii) T(m) values of MPV 60-70S RNA and DNA of all four species were identical. (iii) The removal of MPV sequences endogenous to rhesus tissues by recycling against rhesus DNA resulted in the loss of any hybridizable MPV RNA to the DNAs of baboon, African green, and patas tissues. (iv) Mixing experiments of rhesus, African green, and baboon DNAs resulted in the same kinetics of hybridization as did rhesus DNA alone, when hybridized with MPV 60-70S RNA. These findings demonstrate that sequences that constitute an integral part of the MPV genome are conserved in the DNAs of several different species of Old World monkeys.