FIG. 6.

siRNA-mediated knockdown of endogenous ps20 blocks HIV infection. (a) HeLa indicator cells (2 × 10⁵) were exposed to transfection reagent in the absence of siRNA (mock) or with 50 nM siRNA specific for ps20 or MAPK. Forty-eight hours later, adherent cells were harvested by trypsinization and washed, and viable cells were reseeded at a density of 2 × 10⁴ cells per well and left to adhere for 6 h before the addition of virus (5 μl, 25 μl, 125 μl). Thirty-six hours later, productive HIV infection was determined for cell lysates by use of β-galactosidase levels measured as relative light units (minus background relative light units for uninfected cells) in a luminometer. (b and c) Parallel cultures as described above were set up and samples processed for ps20 mRNA or MAPK mRNA by qRT-PCR. The nonspecific effect of MAPK siRNA on ps20 knockdown is shown in panel b and vice versa (ps20 siRNA on MAPK) in panel c. Error bars represent means of three replicates.