Figure 3.
NCz-SEGN24A develops a strong and Th1-directed humoral response and decreases parasite loads after T. cruzi challenge. (A) Nt-Cz-specific IgG antibodies response. Titers were determined by ELISA in sera samples from C3H/HeN mice vaccinated with either NCz-SEGN24A, by the intramuscular route, or saline (PBS) at 15 days post vaccination. (B) Nt-Cz specific IgG1 and IgG2a titers, determined by indirect ELISA using an isotype-specific secondary antibody. (C) Delayed-type hypersensitivity (DTH) test. Footpad thickness in vaccinated mice was measured before and 72 h after inoculation of 10 μg of Nt-Cz. Results are expressed as the difference in footpad thickness before and after inoculation. (D) Protection against a T. cruzi challenge. Fifteen days after the last immunization, mice were challenged with 3 × 105 K98 clone bloodstream trypomastigotes. Parasitemia after infection was monitored weekly during its acute phase. (E) Area under the parasitemia curve (AUC). Data are expressed as the mean ± SEM of two independent experiments. Asterisks represent statistical significance respect to saline group: *p < 0.05; **p < 0.01; ****p < 0.0001. Hashes represent statistical significance between IgG1 and IgG2 isotypes: ####p < 0.0001. Mann-Whitney test (A), two-way ANOVA plus Sidak's post-test (B), Student's t-test (C,E).