Divergent clonal differentiation trajectories of T cell exhaustion (scATAC-seq)

T cells activated by chronic antigen exposure in the setting of viral infections or cancer can adopt an exhausted T cell (TEx) state, characterized by reduced effector function and proliferative capacity, and the upregulation of inhibitory receptors. Here, we generate a single-cell multi-omic atlas of T cell exhaustion in chronic viral infection that redefines the phenotypic diversity and molecular regulation of TEx states. Longitudinal analysis of the T cell response identifies an early effector phenotype that is epigenetically primed for TEx differentiation. However, clonal T cell trajectories defined using paired single-cell RNA and T cell receptor (scRNA/TCR-seq) sequencing reveal divergent differentiation trajectories among clones that recognize shared antigens, resulting in TEx- or effector memory-biased clone behaviors. Multi-organ clonal analysis reveals that T cell clone behaviors are sensitive to the tissue environment, and the liver niche preclude the development of effector memory phenotypes and induce exaggerated exhaustion. Finally, we show that divergent clonal trajectories are driven by differences in TCR affinity, and that high-affinity T cell clones preferentially adopt the divergent fate, while low-affinity clones adopt effector memory fates that are deleted in high antigen niches. These findings reveal heterogeneity in clonal T cell responses to chronic antigen and link TCR signal strength and epigenetic programming to TEx cell fates and persistence, which may be manipulated for cancer immunotherapy. T cells from 8 and 21 dpi with LCMV-c13 or LCMV-Armstrong were sorted to obtain either gp-33 positive or negative CD8+ T cells. Sorted cells were subjected to single cell ATAC sequencing on the droplet based 10X Genomics platform.