Trypomastigote-induced parasitemia in A/Sn mice immunized with recombinant protein His-65kDa, GST-P1-P3, GST-P4-P7, or His-25kDa. Groups of six mice were immunized at 0, 2, and 4 weeks with His-65kDa, GST-P1-P3, GST-P4-P7, His-25kDa, or adjuvant alone. Each mouse received i.p. 25 μg of recombinant protein adsorbed to alum in the presence of 10 μg of CpG ODN 1826. Two weeks after the last dose was administered, mice were challenged i.p. with 250 bloodstream trypomastigotes. The parasitemia for each individual mouse is represented. The peak parasitemias of mice immunized with His-65kDa or GST-P4-P7 were lower than the parasitemias of animals immunized with adjuvant only, GST-P1-P3, or His-25kDa (P < 0.01 in all cases by Tukey's HSD test). No significant difference was observed when we compared the peak parasitemias of mice immunized with His-65kDa or GST-P4-P7 (P > 0.05). Also, no difference was found when we compared the peak parasitemias of mice immunized with GST-P1-P3 or His-25kDa or adjuvant alone (P > 0.05).