HTLV-1 RT activity and clonality analysis in samples from short-term PBMC cultures from ATL patients pre– and post–in vivo therapy with AZT/IFN. (A) Serial amounts of 5 to 25 pg p19-equivalent RT preparations obtained from supernatants of short-term cultured PBMCs from ATL patients, pre– and post–in vivo therapy with AZT/IFN, were added in the quantitative real-time PCR and HTLV-1 RT activity was assessed. The yield of PCR-amplified products, quantified by densitometry, is shown on the vertical axis. HTLV-1 RT activity in RT preparations obtained from supernatants of MT-2 cells was assayed as a control. (B) HTLV-1 activity, detected and expressed as in panel A, referring to diagnostic samples from ATL patients (8, 9, 10). (C-D) HTLV-1 clonality analysis. The relative abundance of HTLV-1–infected T-cell clones was quantified by linker-mediated PCR and high-throughput sequencing, as previously described.²¹  Each sector of the pie chart denotes a single clone of HTLV-1–infected cells, a clone being defined by the genomic integration site of the (single-copy) provirus. Clones with a relative abundance >1% are colored; lower-abundance clones are shown in gray. The width of each sector indicates the relative abundance of that clone. An OCI > 0.7 is characteristic of ATL.²²  The HTLV-1 proviral loads were as follows: ATL4 (pretherapy, 57.12%; posttherapy, 53.47%); ATL7 (pretherapy, 11.65%; posttherapy, 13.93%). OD-Bkg, optical density–background.