Figure 4.

Apoptosis induction is required for T. whipplei replication. (a) MDM were infected with T. whipplei (MOI 50 : 1) for 4 h, washed and incubated for 48 h in the presence of caspase 8 inhibitor, caspase 10 inhibitor, or both. Apoptosis was determined by TUNEL staining and quantified by examining 3–5 fields per condition. The percentage of TUNEL-positive cells was calculated as the ratio between TUNEL-positive and DAPI-stained nuclei × 100 (control: uninfected cells after incubation for 48 h). (b) MDM were infected with T. whipplei (MOI 50 : 1) for 4 h (uptake), washed and incubated for different periods in the presence of both caspase 8 and 10 inhibitors. Levels of bacterial DNA copy number were determined by qPCR (n=3). ^*P<0.05, Mann–Whitney's U-test