Biological effects of antibodies directed against staphylococcal coagulases.

(A) Purified Coa and vWbp were coated onto ELISA Nunc maxisorp plates and the degree of (A, C) prothrombin or (B, D) fibrinogen binding was measured. To assess antibody perturbation of these interactions, specific or control (αV10) antibodies were added at 1∶10 dilutions. (E, F) Purified active Coa or vWbp was incubated in a 1∶1 molar ratio with human prothrombin. Enzymatic activity of these complexes was assessed by monitoring the rate of S-2238 cleavage (a chromogenic substrate provided in excess). The assay was repeated in presence of specific- or cross-reacting antibodies. Data were normalized to the % average activity without inhibition. All data represent averages of three independent trials. Single asterisks denote statistical significance P<0.05, two asterisks indicate P<0.01 calculated with the two-tailed student's t-test.