HTLV-1 genome and detection of Hbz mRNA and protein in HTLV-1 cell lines. (A) HTLV-1 proviral genome highlighting the HTLV-1 protein open reading frames (ORFs). Hbz including the unspliced mRNA transcript and ORF and the major spliced transcript (SP1) and ORF are detailed. Black line denotes mRNA and gray line in SP1 denotes multiple transcription start sites.²⁷  The location of the Hbz short hairpin target sequences used in this study (Vector 2-4) relative to positive-strand proviral clone numbering is indicated above the Hbz transcript. (B) Total RNA was isolated from HTLV-1 cell lines and negative control Jurkat T cells and subjected to real-time Taqman RT-PCR to quantify the Hbz major spliced transcript (80%-90% of Hbz-specific mRNA^27,32 ). Copy numbers of Hbz mRNA are normalized to 10⁶ copies of the hGAPDH and the average values from 3 independent experiments are presented; error bars denote SD. Western blot analysis of HBZ protein expression (bottom).