Figure 7.

CCP3-4 peptide treatment of LP OmpA⁺Escherichia coli increases the deposition of C3b and the serum sensitivity of the bacteria. (a)LP OmpA⁺E. coli were incubated with either a control peptide (CCP3-2) or a blocking peptide (CCP3-4) for 1 hr on ice and then subjected to serum bactericidal activity. The data represent means ± standard deviation from at least three separate experiments. (b)In separate experiments the bacteria treated with CCP3-4 or CCP3-2 were incubated with 40% NHS for various periods, centrifuged to collect the bacteria, washed and subjected to flow cytometry analysis using anti-C3 and anti-C5 antibodies. The bacteria incubated without primary antibody were used as a negative control. The data represent means of percentage of positive cells in the positive gate ± SD from three different experiments. (c)LP OmpA⁺E. coli were treated with or without peptides as described in (a) and equal number of bacteria were adsorbed onto a nitrocellulose filter. After drying, dot blot analysis was carried out using either anti-C3 or anti-S-fimbria antibody. The blots were exposed on an X-ray film, the film was scanned, the densities of the dots were determined, and plotted on graphs. The experiments were performed at least three times and the data represent mean ± SD.