Fig 5. The length of the primary infection affects the level of circulating murine IFN- γ + T cells after challenge. (A) Timeline of experiment. Infected BALB/c mice were subjected to curative benznidazole treatment initiated 36, 14 or 4 days post-infection (as in Fig 3). 21 days after the end of treatment, they were re-infected (i.p., 10 3 CL Brener trypomastigotes) and blood was collected by venesection on the days indicated. (B) ELISpot analysis. PBMCs were isolated from re-infected mice at pre and post re-infection, as indicated. IFN- γ + PBMCs were quantified after overnight stimulation with a 20-mer peptide pool representing the ASP-2 and TS proteins, as in Fig 1. Data are presented as ex vivo IFN- γ SFCs per 10 6 PBMCs. ( ��� ) p < 0.001; ( � ) p <