The Tax-1 PBM promotes HTLV-1–induced proliferation of human PBMCs. Prestimulated PBMCs (104) were cocultured with 2000 irradiated 729 stable producer cells in 96-well plates. The percentages of proliferating wells were plotted as a function of time (weeks). Representative Kaplan-Meier plots for wtHTLV-1 and HTLV-1ΔPBM (A), and for wtHTLV-2, HTLV-2+C22, and HTLV-2+C18 (B) are shown. (C) Tax-1 PBM does not significantly affect HTLV infectivity. The percentages of newly infected T cells (CD3+, p19+) were enumerated 3 days after plating by immunofluorescence analysis. The mean and SD for each sample were determined from 3 independent experiments using PBMCs from 3 different healthy donors. (D) AZT treatment did not abrogate the enhanced T-cell proliferation mediated by Tax-1 PBM. Microtiter cocultures were treated with 10 μM AZT from 24 hours after plating throughout the end of the experiment. At 4 weeks after plating, 8 random wells from each plate were subjected to the CellTiter96 proliferation assay. The OD values (λ = 490 nm) indicated in y-axis are in direct correlation with the number of proliferating cells in each well. Nontreated cocultures were set up as control. The mean values are indicated by the horizontal lines.
