FIG. 1.

Combination of prime-boost and protein immunizations induces potent cell-mediated and humoral immunity. BALB/c mice were immunized with the F/M, C/C, F+C/M+C, F,C/M,C, or Fnr+C/Mnr+C regimen with a 2-week interval between prime and boost. Two weeks after boosting (day 28), blood was collected from the tail vein. PBMC were assayed for CD8⁺ T-cell responses to Pb9 by ELISPOT assay (A), and sera were assayed for anti-DP4 IgG responses (B) and anti-DP4 isotype profiles (C) by ELISA. Results are from several pooled experiments, except for the F,C/M,C immunized group, where n = 12. ELISPOT assay results are expressed as spot-forming cells (SFC) per million PBMC ± 95% confidence interval. ELISA results are presented as log-transformed end point titers ± 95% confidence interval (n = 12 to 22 per group). ***, P ≤ 0.001.