Impact of secondary TCR engagement on the heterogeneity of pathogen-specific CD8+ T cell response during acute and chronic toxoplasmosis

Initial TCR-dependent engagement of CD8+ T cells results in T cell expansion, and the early events involved in priming influence the generation of diverse effector and memory populations. During infection, some of these activated T cells re-encounter cognate antigen, but whether this influences phenotypic heterogeneity is unclear. To address this issue, OT-I T cells, which are specific for the SIINFEKL peptide from OVA and express the Nur77-GFP reporter of recent TCR activation, were paired with transgenic T. gondii that express OVA to assess the impact of TCR activation on parasite-specific CD8+ T cell responses. Four biological replicates were analyzed for each of Nur77-GFP- and Nur77-GFP+ OT-I from the brains of T. gondii-OVA infected mice 14 days post infection