FIG. 3.
Apoptotic DNA fragmentation of HeLa cervical carcinoma cells treated with MTH-68/H. (A) Electrophoretic analysis of internucleosomal DNA fragmentation. HeLa cells were infected with MTH-68/H at the MOIs indicated in the figure (samples 1 to 9). In the same experiment, MTH-68/H particles were inactivated by boiling in culture medium for 30 min (samples 10 to 12). After 24 h of infection, DNA was extracted and examined by agarose gel electrophoresis as described in Materials and Methods. (B) Time kinetics of apoptosis in HeLa cells analyzed by TUNEL assay. TUNEL assays (panels A1 to F1), used to detect dying cells in HeLa cell cultures infected with MTH-68/H for various durations, were carried out as described in Materials and Methods. To make all the cell nuclei present in the culture visible, nuclei were counterstained with propidium iodide (panels A2 to F2). The fraction of TUNEL-positive cells is indicated in panels A1 to F1. Panels A1 and A2 show untreated, nearly confluent HeLa cell cultures. Panels C to F represent HeLa cultures treated with MTH-68/H vaccine at a 1:1 cell-to-particle ratio for the times indicated.