FIG. 1.

Mapping of the vIRF transcription start sites identified by 5′-RACE and primer extension. (A) Schematic diagram of the vIRF transcripts and the primers used for 5′-RACE (K9F7 and K9F9) and primer extension (pK9R-seq). (B) RT-PCR result of 5′-RACE. The expression of vIRF mRNA in untreated BCBL-1 cells was very low compared with that in TPA-treated cells. RT+, reverse transcriptase treated. (C) Nested-PCR result of 5′-RACE. Different transcription patterns are seen in untreated versus TPA-treated BCBL-1 cells. RT−, control without reverse transcriptase. (D) Primer extension result. Minor and major transcripts had different start sites. Please note that the amounts of mRNA were different (10 μg of RNA for the lane without TPA [TPA−] and 1 μg of RNA for the lane with TPA [TPA+]; see Materials and Methods). The size of the primer extension product was indicated by a sequencing ladder initiated with the same primer. The arrows indicate the positions of the transcription start sites.