FIG. 2.

Comparative complement deposition on smooth (A to C) and rough (D to G) B. abortus (C, F, and G) and B. melitensis (A, B, D, and E) strains. Bacteria were fixed with formaldehyde immediately after the addition of 3% fresh NHS (F) or heated serum (H). The binding of MBL (gray line) and C1q (black line) to bacteria was detected by incubation with the corresponding MAb and secondary FITC-labeled antibodies as described in Materials and Methods. The respective nonspecific binding (NSB) is shown in the shaded area. Cells were analyzed on a FACSort flow cytometer (Becton Dickinson). The panels show the results for 16M (A), WRR51/pRFBUK11 (B), 2308 (C), WRR51 (D), VTRM1 (E), RA1 (F), and RB51 (G). The characteristics of the strains are listed in Table 1. These data are from a representative experiment that was repeated with similar results.