FIG. 6.

Heat-killed H. somnus organisms induce less endothelial cell apoptosis than viable H. somnus organisms. Volumes containing 5 × 10⁴ adherent endothelial cells were incubated with 10⁸ heat-killed (60°C for 60 min) (□) or viable (■) H. somnus organisms at an MOI of 10:1 for 6 h at 37°C with 5% CO₂. Apoptosis was assessed by Hoechst 33342 staining. Controls consisted of untreated (UT) and staurosporine (200 nM; Stauro)-treated endothelial cells. The data illustrate the mean ± SEM of three separate experiments. Statistical analysis was performed by ANOVA followed by the Tukey-Kramer significant difference test.