FIG. 5.

Comparison of the PPS14 antibody response to PPS14-C3d and PPS14-OVA in athymic nude mice. BALB/c nu/nu mice (seven animals per group) were immunized subcutaneously on day 0 with 1 μg of PPS14 either as PPS14 conjugated to OVA (open circles) or to C3d (closed circles). A second immunization with the same PPS14 preparation given in the primary immunization was performed 45 days following the first injection (arrow). The mice were bled 14, 28, and 44 days after the primary immunization and 15 and 29 days after the secondary immunization. Serum anti-PPS14 immunoglobulin concentrations were determined by RABA. Data points represent the GMC for each group of mice. Error bars represent the 95% CI of the geometric mean for each group of sera. Serum anti-PPS14 concentrations were significantly greater for mice receiving two injections of PPS14-C3d than for those receiving two injections of PPS14-OVA at day 14 (P = 0.01), day 28 (P = 0.02), and day 44 (P = 0.03) after primary immunization, but not at day 15 (P = 0.09) and day 29 (P = 0.15) after secondary immunization.