CUT&Tag ChIP-seq analysis of BATF in CX3CR1+ effector , CX3CR1- Ly108- exhausted, or Ly108+ progenitor CD8 T cells during chronic viral infection.

During chronic viral infection, pathogen-specifc CD8+ T cells develop into three main phenotypically and functionally distinct subsets: TCF1hi progenitor, PD-1hi exhausted, and recently identied CX3CR1+ cytotoxic effector cells. Although genetic programs governing progenitor and exhausted subset formation have been well-studied, how CX3CR1+ effector CD8+ T cell differentiation is transcriptionally and epigentically regulated remains elusive. In this study, our single cell transcriptomics and epigenetic assays revealed that three subsets of virus-specific cells were governed by distinct gene regulatory networks (GRNs) and epigenetic landscapes. Computational analyses demonstrated a striking similarity between the CX3CR1+ subset and short-live effector cells (SLECs) from acute LCMV infection. Consistently, genetic deletion of T-bet (Tbx21) significantly diminished the formation and function of the CX3CR1+ subset. Importantly, we identify that the transcription factor (TF) BATF is required to maintain a permissive chromatin structure that allows differentiation transition from TCF1+ progenitor to CX3CR1+ effector cells. Intriguingly, haplodificiency of BATF in CD8+ T cells abolished CX3CR1+ effector subset formation. Lastly, we found that BATF directly bound to key genetic regions such as Tbx21 and modulated their enhancer accessibility to facilitate progenitor to CX3CR1+ effector cell transition. These mechanistic insights can be harnessed to overcome T cell exhaustion in treating chronic infections and cancer. Overall design: BATF CUT&TAG ChIPseq, 3 samples (CX3CR1+ , CX3CR1- Ly108- PD1+, or Ly108+ CD8 T cells), 3 biological replicates per sample, from LCMV-Cl13 infected C57BL/6 mice.