Fig 1.

Effect of a single challenge of chronically infected mice with homologous T. cruzi parasites. Sylvio X10/4-infected chronic mice that were subjected to i.v. challenge with a single dose of homologous parasites and unchallenged chronically infected mice were euthanized at 10 and 60 days p.c. (A) Numbers of spontaneous and anti-CD3/CD28-induced IFN-γ-producing CD4⁺ and CD8⁺ cells in the spleen; (B) anti-T. cruzi IgG2a and IgG1 antibody serum levels (the 1/12,000 dilution is shown) (O.D, optical density); (C) intensity of inflammatory infiltrates in the pericardium, endocardium, myocardium, and global heart tissue. Data represent the results determined with unchallenged (■) and challenged (□) chronically infected mice. *, P < 0.05; **, P < 0.01 (compared to unchallenged chronically infected mice). Representative experiments are shown.