Figure 1.
T. cruzi-specific antibody response in vaccinated mice. (A) Schematic of experimental plan is shown. C57BL/6 female mice were immunized with six different compositions of vaccines as described in Materials and Methods. Mice were immunized with dose 1 at day 0, dose 2 at day 21, and on day 42 euthanized to examine the vaccine-induced responses or challenged with Tc and then euthanized at day 63 to study the significance of vaccine in providing protection from infection. Vaccines (per dose) were constituted with 25-μg each of pCDNA3.TcG2 and pCDNA3.TcG4 plasmid DNA (intramuscular) and/or 1 × 108 T. rangeli fixed with 0.1% glutaraldehyde (fTr) with or without 5-μg Quil A (QA, subcutaneous). (B–G) T. cruzi-specific IgG (B), IgG1 (E), IgG2a (F), and IgG2b (G) antibodies in sera samples were measured by an ELISA. The vaccine-induced IgGs specificity for T. cruzi was determined after pre-adsorbing the sera samples with T. rangeli soluble lysate (C) and avidity of vaccine induced IgGs was calculated as [O.D. with urea/O.D. without urea treatment] × 100 (D). Sera samples from non-vaccinated or infected mice were used as negative and positive controls, respectively. Data (mean ± SD) are representative of two independent experiments (n = 4 mice per group per experiment, duplicate observations per sample), and significance is presented as * (none vs. vaccinated) or ∧ (comparison among vaccinated groups). The p-values of <0.05, <0.01, and p < 0.001 are annotated with one, two, and three symbols, respectively.