Figure 7.

Vpr counteracts PHF13-mediated suppression of viral gene expression. U2OS-C5 cells were either mock transfected or transfected with control siRNA (csiRNA) or siRNA constructs directed against PHF13 (siPHF13). Twenty-four hours later cells were infected with 100 ng p24 VSVG pseudotyped HIV-1 NL4-3 IRES-eGFP or the ΔVpr variant for 6 h, washed and incubated for additional 18 h in medium with or without 1 µg ml⁻¹ doxycycline. Twenty-four hours later cells were analysed by flow cytometry or ELISA for (a) the percentage of GFP+, hence HIV-1-infected cells, (b) MFI of the GFP+ cells as marker for LTR transactivation and (c) the amount of p24 released in the supernatants. Mean values and standard deviations were calculated from four (a and b) or three (c) independent experiments and normalized to the HIV-1-infected and mock-treated control. Statistics were calculated with one-way analysis of variance (ANOVA) with a Bonferroni multiple comparison post-test. *p < 0.05; **p < 0.01; ***p < 0.001; n.s., not significant.