Figure 7.

Recruitment of serum-derived FI to CipA mediates escape of A. baumannii from complement-mediated killing. CipA production in different A. baumannii strains was verified by Western blot analysis (A). CipA was detected in A. baumannii cell lysates (10 µg each) by using an anti-CipA antibody (1:100). Binding of FI to A. baumannii strains upon NHS incubation was assessed by Western blotting using an anti-FI antibody (1:1,000) (B). Survival of A. baumannii strains in human serum (C, D). 5 x 10⁷ cells of A. baumannii ΔcipA::cipA (●), ΔcipA (▲), and ΔcipA::cipA E360P (■) were incubated in increasing amounts of human serum for 2 h at 37 °C, serially diluted and cfu counts determined. Cfu counts were related to controls incubated in LB medium instead of serum, for which survival was set at 100%. Shown are results from at least three independent experiments (C). Survival of A. baumannii strains at 50% NHS (D). **, p ≤ 0.002, ****, p ≤ 0.0001, n.s., no statistical significance, one-way ANOVA with post-hoc Bonferroni multiple comparison test (confidence interval = 95%). p; pellet; s, supernatant; w, final wash fraction, e; eluate fraction.