FIG 8.

HTLV 5′UTR drives translation initiation in HeLa cells. (A) Schematic representation of the dual luciferase bicistronic DNA reporters used in the transfection assays. The bicistronic reporters are expressed from the SV40 promoter and receive a poly(A) tail by cleavage and polyadenylation at the SV40 poly(A) signal (SV40pA). (B) The dlΔEMCV, HIV-1 IRES, or dl HTLV-1 5′UTR vectors were cotransfected into HeLa cells with the pcDNA3.1 lacZ (50 ng) vector that expresses β-galactosidase from a cap-dependent transcript (12, 28). Cotransfection of β-galactosidase serves as an internal control for transfection efficiency. RLuc and FLuc activities were measured and normalized to the β-galactosidase activity. Values are expressed as the RTA (%) relative to the dl HIV-1 IRES (12), which was set to 100%. The values shown are means ± the SEM for three independent experiments, each performed in triplicate. Statistical analysis was performed by a one-way ANOVA test, followed by a Tukey's multiple test comparison. *, P < 0.05.