Tat decreases HIV-1 frameshift efficiency in a dose-dependent manner. (A) The Fluc/Rluc ratio was assessed in lysates from Jurkat T-cells cotransfected with pFRT-Tat and pDual-HIV*, pTP-HIV, pΔTP-5′UTR-HIV, p5′UTR-HIV, or pCAT-5′UTR-HIV. The Fluc/Rluc ratio is presented relative to its value in absence of Tat, which is set at 100% for each construct. Results are the mean ± SEM of at least three independent triplicate experiments. (B,C) Cotransfection with pFRT-Tat and pΔTP-5′UTR-HIV, p5′UTR-HIV, or pCAT-5′UTR-HIV. (B) Impact of Tat on translation efficiency. The Rluc activity was divided by the level of Rluc mRNA quantified by qPCR. The Rluc/mRNA ratio is presented relative to the value in the absence of Tat, which is set arbitrarily at 1. Rluc/mRNA ratios were measured in triplicate, and one representative experiment is shown. (C) Relative expression of the dual-luciferase mRNA in presence of Tat. The value in the absence of Tat was arbitrarily set at 1. The mRNA levels were quantified in cell lysates by qPCR. The analysis was performed in triplicate, and one representative experiment is shown.