FIG. 6.
Matrix protein alone induces apoptosis by a TRAIL-dependent mechanism involving the caspase-8 pathway. (A) HeLa cells were infected with THA, MOK, or LAG (MOI, 15) and processed for the TUNEL assay. (B) Proteins (20 μg) were subjected to SDS-polyacrylamide gel electrophoresis, blotted, and probed with anti-human caspase-8. β-Actin was included as a loading control. (C through F) HeLa cells were either mock transfected (NTF) or transfected with pGFP (positive control), pM-GFP, or pM-(His)6. Cells were then processed for a TUNEL assay at the indicated time points (C), a caspase-8 activity assay at 24 h posttransfection (D), and Western blotting with anti-human caspase-8 (E). Cells were also processed for a neutralizing assay using an anti-human TRAIL neutralizing antibody at 48 h posttransfection (4.4 μg/ml) (F). Results are means of data obtained in two independent experiments. Error bars, standard deviations.