FIG. 4.

FN binding by H. ducreyi is inhibited by an anti-DsrA MAb and by hemoglobin. The effect of preincubation of MAbs or purified protein on the ability of H. ducreyi to bind FN was measured using the unlabeled FN binding assay (see Materials and Methods). A panel of MAbs (purified IgGs), as well as hemoglobin (Hb) and transferrin (Tf), each at 50 μg/ml, were tested as potential inhibitors of FN and VN binding by H. ducreyi. Ponceau S staining (not shown) of the nitrocellulose membrane indicated approximately equal loading of total proteins for all the strains.