FIG. 1.

Enhancement of the PPS14 antibody response by conjugation of C3d to PPS14. BALB/c mice (15 animals per group) were immunized subcutaneously on day 0 with either 0.1 μg (left) or 1.0 μg (right) of PPS14 either as the PPS14-glycine control (open circles) or as PPS14-C3d conjugate (closed circles). A second immunization with the same PPS14 preparation given in the primary immunization was performed 47 days following the first injection (arrows). Serum samples were obtained 10 and 25 days after the primary immunization and 10 and 23 days after the secondary immunization. Serum anti-PPS14 immunoglobulin concentrations were determined by RABA. Data points represent the GMC for each group of mice. The error bars represent the 95% CI of the geometric mean for each group of sera. Data were analyzed by Student's t test on log-transformed data; the P values for the PPS14-C3d conjugate versus the PPS14-glycine conjugate are shown above the error bar at each time point.