Dose-dependent binding of PilB to various protein ligands. Increasing concentrations of purified PilB was added to constant concentrations of immobilized putative ligands, and binding was quantified by ELISA. BSA served as negative control. The results are the average ± SDs from at least three independent experiments. (A) Binding of PilB to fibrinogen, fibronectin, elastin, and laminin. (B) Binding of PilBvWA, consisting only of the vWA module, to fibrinogen and fibronectin.