Small RNA expression from the oncogenic region of a highly oncogenic strain of herpesvirus saimiri.

Herpesvirus saimiri induces acute lymphomas and leukemias in primates and rabbits. Sequence divergence of the right end unique region of the genome classifies virus strains into three groups (A, B, and C), and previous studies have demonstrated correlation between DNA grouping and oncogenicity. In order to relate different oncogenicity to the underlying molecular mechanisms, we reported earlier the expression of a bicistronic mRNA from the oncogenic region in a highly oncogenic group C strain, and the present study is the first report on small RNA transcripts from the same region. The transcripts and 6.2 kbp on the oncogenic region were sequenced and characterized. We show that four U-type small RNAs are expressed in tumor cells transformed by this strain, in contrast to the seven small RNAs reported from a weakly oncogenic group A strain. Sequence comparisons between the two strains showed that the right end region of strain 484-77 of group C is about 1 kbp shorter. The conserved 5' AUUUA repeats of some small RNAs, and their proposed implication in lymphokine mRNA stabilization, are also discussed.