Fig. 5.

Pathogen exposure triggers an expansion of antigen-specific memory CD8⁺ T cell subset. Blood of C57BL/6 mice immunized (30 dpi) or immunized and challenged with 250,000 CL culture trypomastigotes (10 dpi) was analyzed for VNHRFTLV-specific CD8⁺ T cells by tetramer staining (a). Percentage of pathogen-specific, vaccine unrelated CD8⁺ T cells (Tskb20) by tetramer staining in blood (I). Zebra-plots showing VNHRFTLV-tetramer⁺ population on indicated groups (b). In vivo CTL assay (c). Spleen cells from C3H donor mice were loaded with peptides, KEEASSAV (Nt-Cz domain), GELRIIKSV (α-linker-motive), and TEWETGQI (ASP2 domain), or unloaded. Cells were stained with CFSE, mixed in an equal ratio, and i.v. injected to naïve (c-di-AMP), Traspain+c-di-AMP immunized or Traspain+c-di-AMP vaccinated and T. cruzi infected mice at 45 dpi (Vaccinated + T. cruzi). Representative density-plot showing percentage of CFSE populations in the indicated groups. Crosses represent the median value of each dimension in each gate (d). pep 1: KEEASSAV, pep 2: GELRIIKSV, pep 3: TEWETGQI. Results are expressed as mean ± SEM, and represent at least three independent experiments, n = 6 per group (a, b) and n = 3 per group (c, d), ***p < 0.001, **p < 0.01, *p < 0.05. 1way-ANOVA + Tukey’s multiple comparisons test (a)