Fig. 2.

YopH-mediated inhibition of the immediate-early Ca²⁺ response in human neutrophils. Real-time monitoring of intracellular Ca²⁺ in neutrophils infected with chloramphenicol-treated Y. pseudotuberculosis strains: plasmid-cured mutant (YPIII), wild-type bacteria (WT), a yopH deletion mutant (ΔyopH), and a double yopByopD-deletion mutant (ΔyopB,D). The mean numbers (± SEM) of Ca²⁺ peaks (300–600 nM) generated within 10 min of infection in nine independent experiments were as follows: YPIII, 3.41 ± 0.62; wild type, 0.22 ± 0.10; ΔyopH, 3.39 ± 0.53; ΔyopB+D, 3.28 ± 0.81.