FIG 5.

Effect of the addition of a nonbactericidal anti-NspA MAb on complement deposition on live bacteria. (A and B) Deposition of C4b and C3b, respectively, by 1:50 dilutions of anti-FHbp antisera, anti-NspA MAb (5 μg/ml), or a combination of anti-FHbp antisera (1:50) with anti-NspA MAb (5 μg/ml). (A) S1 and R1 isolates; (B) S2 and R2 isolates. Solid black line, resistant (R) isolates; dashed black line, sensitive (S) isolates; shaded areas, negative-control without antibody. The data were replicated in three experiments testing 5% IgG-depleted human serum as a source of complement. We also obtained similar respective results for the R1 and S2 isolates testing 20% IgG-depleted human serum as a source of complement.