Fig. 9: Single dose DKO immunization of mice is protective against lethal challenge.

a Timeline of immunization and WT challenge of mice. Mice were given a single DKO immunization with 10⁵ parasites then challenged with WT parasites 24 weeks post-immunization (n = 5). Non-immunized mice served as controls. Terminal analysis of DKO-immunized mice was conducted 24 weeks after WT challenge. b Survival curve of WT-challenged non-immunized control mice and DKO-immunized mice. All DKO-immunized mice survived WT challenge whereas all non-immunized mice died within 18–25 days post-challenge. Challenged DKO-immunized animals were observed for up to 240 days post challenge and no animals developed clinical disease. Treatment of these animals with dexamethasone (Dexa) does not induce clinical disease, alter survival or cause the emergence of parasites from tissues in any animal in the group (not shown). c Explantation of indicated tissues in parasite culture medium from WT-challenged non-immunized (at or near the time of death) or DKO-immunized mice 240 days post-infection. d Histopathologic analysis of heart sections of WT-challenge non-immunized (left panel) and DKO-immunized mice (right panel). This experiment contained 5 mice per group. The Log-rank (Mantel-Cox test) was used for the Kaplan–Meier analysis. P < 0.05.