Fig 3. C4BP binds to OpaD+ Gc.

OpaD+ Gc was incubated with 25% normal human serum (orange; UVA), heat-inactivated (HI) serum (brown), heat-inactivated C4BP-depleted (depl) serum (blue), or purified C4BP (50 μg/ml; purple) for 20 minutes at 37°C. Gc was fixed and stained with DAPI for intact bacteria (blue) and for C4BP using anti-C4BP antibody followed by Alexa Fluor 488-coupled goat anti-rabbit IgG (green), and analyzed by imaging flow cytometry. (A) Representative images (image numbers 7449 and 19815) of a single serum-incubated (top) and PBS-incubated (bottom) bacterium. (B) is the percent C4BP-positive bacteria and (C) is the mean intensity of AF488 fluorescence of the total bacterial population. In B-C, results are the mean ± SEM of 3 independent experiments. Statistical analyses were performed using one-way ANOVA with Tukey’s post-hoc comparisons to PBS. *p<0.05, **p<0.01,****p<0.0001.