FIG. 6.

Apoptosis of cells upon infection with adenovirus carrying multiple E1 mutations. The impact of E1B mutations on the apoptotic response of infected cells was studied by examining cell morphology and PARP cleavage. (A) Morphology of infected cells. A549 cells were mock infected or infected with wild-type adenovirus (Ad wt) or the indicated adenovirus mutants at a multiplicity of infection of 10 for 48 h. Cell morphology was then examined by light microscopy. (B) PARP cleavage in infected cells. LS174T cells were mock infected or infected with the indicated adenovirus mutants at a multiplicity of infection of 20 for 30 h. The cells were then harvested and subjected to immunoblot analysis of PARP, as well as p53 and its target genes and actin (loading control). The top band in the PARP detection panel represents full-length PARP; the lower band (PARP cleaved) corresponds to the characteristic cleavage fragment that caspase 3 leaves after proteolysis.