Mapping of RNA transcribed from a region of the Herpesvirus saimiri genome required for oncogenicity.

A region of the Herpesvirus saimiri genome that is not essential for replication of the virus has recently been shown to be required for its oncogenicity in New World primates. We have examined the RNAs derived from this region of the genome in permissively infected cells. Two polyadenylated RNAs, of 4.9 and 2.3 kilobases, were the major species coded for by this region of the genome. These two RNAs, as well as a much less abundant RNA of 6.5 kilobases, were specifically altered in two different nononcogenic deletion mutants of H. saimiri. The 4.9- and 2.3-kilobase RNAs were mapped by S1 nuclease and exonuclease VII digestion of DNA-RNA hybrids. The transcripts were found to be spliced, overlapping, and transcribed from right to left on the genetic map, with their 3' termini each ca. 150 base pairs from the left border between the unique and repetitive DNA regions. These RNAs were not detected at immediate early times after infection. The possible role of these RNAs in the origin of the malignant T-cell lymphoma caused by this virus is discussed.