Fig. 4

Growth curve of R. rickettsii in BME26 cells treated with either staurosporine or the caspase-3 inhibitor Z-DEVD-Fmk. BME26 cells were treated with staurosporine (400 nM) or the caspase-3 inhibitor Z-DEVD-Fmk (10 μM). Untreated cells served as the control. After 1 h, cells were inoculated with R. rickettsii. The number of rickettsiae after 6, 24, 48, 72, 96 and 120 h was determined by quantitative PCR using specific primers and a hydrolysis probe for the single-copy gene gltA of Rickettsia spp. ^aSignificant difference in rickettsial growth in cells treated with Z-DEVD-Fmk (P < 0.02, Student’s t-test),^b significant difference in rickettsial growth in cells treated with staurosporine (P < 0.007, Student’s t-test), compared to the control. Error bars: ± standard deviation (n = 3)