Figure 5
(a) HeLa cells were co-infected with AdCMV-rtTA and AdTRE-E1 at multiplicity of infection (MOI) 10, and incubated with (open circle) or without (closed circle) Dox. As a positive control, HeLa cells were also infected with AdCMV-E1 at MOI 10 (open square). The viability of the cells was evaluated by MTS assay, and the survival fraction was shown as percentage of the intact cells (closed square) at each point. After 3 days, the survival fraction of the cells infected with AdCMV-E1 decreased rapidly. When incubated with Dox, co-infection with AdCMV-rtTA and AdTRE-E1 also showed a strong cell-killing effect; however, the cell-killing effect was weak without Dox. At days 5 and 7, there was a significant difference in the cell-killing effect between the cells incubated with (open circle) or without (closed circle) Dox (*P<0.05). Cell lysis was delayed when Dox was added in the medium 3 days after infection (open triangle). Mean±s.e. of triplicate determination is shown. (b) Crystal-violet-staining image of the cells co-infected with AdCMV-rtTA and AdTRE-E1 with (upper panel) or without (lower panel) Dox. The cells were stained at day 7 after infection.
