Exhaustion, the early steps.
"Here, we performed single-cell RNA-sequencing and single-cell ATAC-sequencing of CD8+ T cells responding to LCMV-Armstrong (LCMV-Arm) or LCMV-Clone 13 (LCMV-Cl13), which result in acute or chronic infections, respectively."
https://journals.plos.org/plosbiology/article?id=10.1371/journal.pbio.3001983