Qualitative analysis of cytotoxicity (crystal violet assay). Four different viruses (5/3 ΔE3 ADP IFN, 5/3 Cox2 ΔE3 ADP IFN, 5/3 Cox2 ΔE3 ADP Luc, and Ad5 Wt) were analyzed to assess their cell killing effects in two EAC cell lines (OE19 and OE33). The plates were analyzed at two time points following viral infection at 10 viral particles (vp) per cell: the first time point was when the 5/3 Cox2 ΔE3 ADP IFN started to show oncolysis, and the second time point was when the Ad5 Wt virus started to show oncolysis. The 5/3 ΔE3 ADP IFN virus killed almost all of the cells at an early time point in all cell lines tested. The 5/3 Cox2 ΔE3 ADP IFN virus (identical aside from the addition of a tissue-specific promoter) had a slightly less potent cytocidal effect at earlier time point, but still killed the majority of cells by the later time point in all cell lines tested. Following infection with the 5/3 Cox2 ΔE3 ADP Luc virus, most cells still remained alive at the end of the experiment