Figure 6B depicts the evolution of parasite load during 13 days. Mice previously infected with TCC wild type metacyclic trypomastigotes a year before were still considerably protected against the virulent challenge. Despite displaying a more attenuated behavior, TCC dhfr-ts+/− infection produced a similar protective effect compared to TCC wild type parasites. Overall, these observations indicate that both, wild type and dhfr-ts+/− TCC primo infection conferred a long-lasting protection against secondary infections. This evidence concerns the gene DHFR and infection.