Fig. 5: Vaccine efficacy in controlling Tc-induced cardiac pathogenesis in pregnant mice.

Female mice were immunized with nano2/4, infected with Tc, and mated with males as described in Fig. 1a. Similarly treated but not mated females were used as controls. Parasite burden. Total DNA was isolated from heart tissues of control (a) and pregnant (b) groups and submitted to real-time qPCR amplification of Tc18SrDNA sequence (normalized to murine Gapdh). Parasite burden and percent of mice positive for Tc are plotted as a colored distinction between mice that were not infected (black triangle), and mice with detectable (red triangle) or undetectable Tc (gray triangle). Histology. Paraffin-embedded 5-µm heart tissue sections were subjected to (c, f) H&E and (i) Masson’s Trichrome staining, and representative images identifying inflammatory infiltrate, necrosis, and fibrosis in control (panels a–d) and pregnant (panels e–h) female groups are shown (scale bar: 20 μm). Thresholding methods with Image J software were applied to calculate the percent nuclei as a measure of inflammatory infiltrate (d, e), tissue tear as a measure of necrosis (g, h), and blue-colored collagen deposition as a measure of fibrosis (j, k), as described in methods. Number of females: C (n = 8), Va (n = 6), Tc (n = 11), VaTc (n = 10), P (n = 6), VaP (n = 6), TcP (n = 10), VaTcP (n = 6). In graphs, each mouse value is presented by a triangle, and mean ± SEM values derived from 2 tissue sections per mouse (each slide analyzed in >9 microscopic fields) are plotted. Significance was calculated by Students’ unpaired t-test with or without Welch’s correction or Mann–Whitney U-test and p-values of <0.05, <0.01, <0.001, <0.0001 are annotated with one, two, three, and four symbols, respectively. The horizontal bar indicates the compared groups. Detailed data are presented in Supplementary Table 6.