Figure 8. Complement inhibits IP32953 ΔailΔyadA dissemination to the spleen, but not persistence in the lungs.

(A) The indicated IP32953 and IP2666 strains were diluted in a 1:1 volume in either FBS or HIS. Following a 2h incubation at 37°C, the incubated cultures were plated for CFU. Killing by serum was determined by comparing the CFU recovered in FBS to that recovered after incubation in HIS. Values were normalized to WT IP32953, which was set at 1. Statistical significance was determined by a One-Way ANOVA followed by Dunnett’s post-test. Asterisk(s) indicate statistical significance as compared to WT IP32953 values. (**p<0.01). Data is a compilation of 3 independent experiments done in triplicate. Bars indicate mean and error bars indicate SEM. (B–D) BALB/c mice were intraperitoneally injected with CVF to deplete complement or mock treated with PBS. At 24 hours post treatment, the mice were intranasally infected with 250 CFU of WT IP32953 or ΔailΔyadA. At 96 h.p.i., the (B) lungs, (C) spleens and (D) livers were harvested and plated for CFU. Data from 2 independent experiments of 21.33–3.65%. The mean and SEM is from 4–6 independent 3 mice each is shown, where each dot represents an individual mouse. Open symbols represent no bacteria recovered and limit of detection. Bars represent the geometric mean. Statistical significance was determined by One-Way ANOVA with Tukey’s post-test (ns=not significant, *p<0.05, **p<0.01, ***p<0.001)