Stable CD8+ T cell memory during persistent infection

In contrast to antigen-independent, cytokine-driven CD8+ T cell memory arising from acute resolving infections, CD8+ T cell memory during chronic infections is thought to be sustained primarily by the presence of antigen, comprising a population of relatively short-lived T effector memory cells. Consistent with this idea, we have observed that the majority of CD8+ T cells exhibit an effector memory phenotype during experimental chronic infection with Trypanosoma cruzi, a protozoan parasite that causes significant morbidity and mortality throughout Latin America. The goal of this study was to explore the possibility that long-term memory is generated in spite of persistent infection by T. cruzi. We report that in contrast to what is typically observed during other persistent infections, a stable population of parasite-specific CD8+ T central memory cells capable of antigen-independent survival is maintained in mice despite the presence of persistent antigen.