<i>P</i>. <i>aeruginosa</i> binds the terminal complement regulator vitronectin.

<p><b>A</b>, Binding of vitronectin to <i>P</i>. <i>aeruginosa</i> strain SG137 was assayed by flow cytometry. Bacteria were incubated with vitronectin (10–50 μg/ml) and bound vitronectin was detected with polyclonal vitronectin antiserum and Alexa488-labeled rabbit antiserum. Bacteria incubated with vitronectin specific antiserum and Alexa488-labeled rabbit antiserum served as controls. <b>B</b>, Vitronectin binds to <i>P</i>. <i>aeruginosa</i> and binding was dose-dependent. Four laboratory strains of <i>P</i>. <i>aeruginosa</i> were analyzed for vitronectin binding using a whole cell ELISA. Whole bacteria were immobilized onto microtiter plates and vitronectin (1–5 μg/ml) was added. Bound vitronectin was detected with polyclonal vitronectin antiserum followed by HRP-conjugated anti-rabbit. <b>C</b>, Vitronectin bind to <i>P</i>. <i>aeruginosa</i>. <i>P</i>. <i>aeruginosa</i> strains SG137, ATCC 27853, NCTC 10662 and PAO1 were incubated with NHS. Bacteria were washed, lysed, separated by SDS-PAGE and analysed by Western blotting. Bound vitronectin was detected with polyclonal vitronectin antiserum and HRP-conjugated anti-rabbit. A representative experiment of three is shown. <b>D</b>, Vitronectin bound to both laboratory and clinical <i>P</i>. <i>aeruginosa</i> strains. Binding of vitronectin (5 μg/ml) to immobilized bacteria (0.5x10⁷) was assayed by ELISA. Bound vitronectin was detected with polyclonal vitronectin antiserum followed by HRP-conjugated anti-rabbit pAb. The mean values of three independent experiments and standard deviations (SD) are presented. Statistical significance of differences was estimated using Student’s t test. **, <i>p</i>≤ 0.01; ***, <i>p</i>≤ 0.001.