FIG. 2.

Binding of fH to purified PspC and PspCΔPro (A) or pneumococcal strains D39 or D39/pspC mutant (B) as determined by ELISA. fH (5 μg/ml) was incubated with 0.5 μg of bound PspC, PspCΔPro, D39, or D39/pspC mutant dried onto microtiter plates overnight. Binding of fH was detected by the sequential addition of goat anti-fH (1:2,000), HRP-conjugated donkey anti-goat IgG (1:2,000) and substrate prior to reading the OD₄₉₀. PspC and fH controls are also indicated on both the graphs. Experiments were repeated three times in triplicate, with the means and standard deviations indicated.