Exogenously expressed HBZ results in dose-dependent repression of Tax-mediated transcription and p19 Gag production. 293T cells (1.5 × 105) were cotransfected with 1 μg wtHTLV-1 proviral clone or negative control DNA, 0.1 μg LTR-1–Luc, and 0.01 μg TK-Renilla, and varying concentrations (0.1-0.4 μg) of HBZ or HBZΔLZ expression vectors as indicated. (A) Tax function was measured as firefly luciferase activity (RLU indicates relative light units) from LTR-Luc normalized to Renilla luciferase activity. (B) Culture supernatant was collected from cells in panel A and assayed for p19 Gag production by ELISA. (C) Western blot analysis to confirm increasing concentrations of HBZ and HBZΔLZ used in panels A and B. β-actin levels were assessed as a loading control. *Statistically significant dose-dependent reduction of Tax transactivation activity or p19 Gag production. Statistical significance was determined by analysis of variance (ANOVA) followed by Tukey test. The histogram presents the average values from 3 independent experiments; error bars denote SDs.
