FIG. 5.

The binding of C1q, a subcomponent of the complement classical pathway component C1, was measured by ELISA as reported previously (11, 54). The sera were tested before ■ and after  the third vaccination. Plates were coated with OprF-OprI and incubated with 50 μl of the respective 1:4-diluted serum and 50 μl of complement source. Binding was measured with peroxidase-linked anti-C1q antibodies, and ortho-phenylen-diamine was used as the substrate.