FIG. 3.

Trypomastigote-induced parasitemia and mortality in A/Sn mice immunized with plasmids containing asp-related ORFs expressed in amastigotes of T. cruzi. A/Sn mice were immunized with plasmid pIgSP-asp-3(5340), pIgSp-asp-4(7015), pIgSP-clone22 (Colombian strain), or pcDNA3. Fourteen days after the last immunization, mice were challenged i.p. with 250 bloodstream trypomastigotes of the Colombia strain. In the top panel, the course of infection was estimated by the number of trypomastigotes per ml of blood. Results represent the mean ± standard deviation obtained from five or six mice immunized with each plasmid. At the peak of infection, the parasitemias of mice immunized with each plasmid were compared by one-way analysis of variance and Tukey's honestly significant difference tests. The peak parasitemias of mice immunized with pIgSP-asp-3(5340) or pIgSp-asp-4(7015) were not different from those of animals injected with pcDNA3 (P > 0.05 in both cases). However, a significant difference was detected when we compared the peak parasitemias of mice immunized with pcDNA3 or pIgSP-clone22 (Colombian strain) (P < 0.01). In the bottom panel, Kaplan-Meier curves for the survival of mice immunized with pIgSP-asp-3(5340), pIgSp-asp-4(7015), pIgSP-clone22 (Colombian strain), or pcDNA3. The results of the comparison were as follows: (i) pcDNA3 × pIgSP-asp-3(5340), P = 0.0007; (ii) pcDNA3 × pIgSP-asp-4(7015), P = 0.0018; (iii) pcDNA3 × pIgSP-clone22 (Colombian strain), P = 0.0007; (iv) pIgSP-asp-4(7015) × pIgSP-asp-3(5340), P > 0.05; (v) pIgSP-asp-3(5340) × pIgSP-clone22, P > 0.05; and (vi) pIgSP-asp-4(7015) × pIgSP-clone22, P > 0.05. Data are representative of two experiments performed with similar results.