FIG 3.

Induction of specific antibody responses in mice immunized with recombinant P. vivax CSP antigens. (A) Mice were immunized with three doses 21 days apart, and the antibody titers were analyzed according to the timeline shown. The serum IgG responses to P. vivax CS antigens were determined in C57BL/6 mice immunized s.c. with the purified proteins in a formulation containing the adjuvant poly(I·C) (B to D) or emulsified in CFA or IFA (E to G). Mice were immunized with His₆-PvCSP-VK210 (10 μg/dose/mouse), His₆-PvCSP-VK247 (10 μg/dose/mouse), His₆-PvCSP-Vivax-like (10 μg/dose/mouse), a protein mixture (His₆-PvCSP-VK210, His₆-PvCSP-VK247, and His₆-PvCSP-Vivax-like, 30 μg/dose/mouse), or His₆-PvCSP-All-CS-epitopes (30 μg/dose/mouse). Serum IgG titers of antibodies against recombinant proteins representing each allelic form of PvCSP were measured as indicated. The results are expressed as means ± SD (n = 6). Statistical comparisons by one-way ANOVA of the antibody titers from mice immunized with formulations containing the adjuvant poly(I·C) (B to D) show significantly higher antibody levels in animals immunized with the protein mixture (P < 0.01, asterisks). Comparisons of the antibody titers of mice immunized with formulations containing the adjuvant CFA-IFA and recombinant proteins did not show statistically significant differences.