Fig. 1

Identification of antisense transcription from the BLV provirus. a Ideogram showing location of the BLV sense transcripts originating in the 5′LTR as well as the BLV microRNAs. Below are shown the sense (red) and antisense (blue) reads mapping to the region from stranded RNA-seq of the L267 tumor B cell line. Based on observed antisense split reads and the results of 5′/3′RACE three BLV antisense transcripts were identified. All three share the same exon 1, with the 5′ end located primarily at either position 8591 or 8650. AS1-S ends as the transcript enters the BLV microRNA region and has a poly A tail. AS1-L extends beyond the BLV microRNA region and reads with a poly A tail can be observed at position ~5237. Finally, AS2 has a small exon 2 (~125 bp) and no poly A tail was observed in the majority of samples examined. b Rt-PCR using the YR2 and L267 cell lines and PBMCs from an uninfected sheep. Control DNA was derived from YR2. Primers used span the splice sites for AS1 and AS2. For AS1-L the reverse primer was upstream of the BLV microRNAs. Primers for Beta-actin (ACTB) were included as a positive control. (Rt+ reverse transcriptase positive, Rt− reverse transcriptase negative, base pair coordinates correspond to NCBI Accession: KT122858)