Figure 4
Expression of Ide Ssuis reduces C3 deposition on the surface of an unencapsulated mutant triggered by IgM-mediated activation of the classical complement pathway. C3 antigen bound to the surface of the unencapsulated mutant 10cpsΔEF and the double mutant 10cpsΔEFΔide Ssuis was detected through flow cytometry analysis. Bacteria were opsonized with sera from colostrum-deprived piglets (SCDP) or SCDP spiked with purified porcine IgM (SCDP plus IgM). To inactivate the classical complement activation pathway SCDP plus IgM was pretreated with EGTA MgCl2. As control non-opsonized bacteria (incubated in PBS) were incubated with the C3 specific antibody. (A) The percentage of bacteria with antibody-labelled C3 and (B) the mean fluorescence intensity of the samples are shown. Bars and error bars represent mean values and standard deviations, respectively. Significant differences are indicated (*, p < 0.05; **, p < 0.01; ***, p < 0.001).