Early emergence of T central memory precursors programs clonal dominance during chronic viral infection [bulkRNAseq]

Chronic infection with cytomegalovirus (CMV) leads to long-term maintenance of extraordinarily large CMV-specific T cell populations. The magnitude of this so-called ‘memory inflation’ is thought to be mainly determined by the availability of antigenic stimuli during the chronic phase of infection. However, by mapping the long-term development of CD8+ T cell families derived from single naive precursors, we find that T cell fate decisions, taken during the acute phase of murine CMV infection, can alter the level of memory inflation by more than 1000-fold. Counterintuitively, a T cell family’s capacity for memory inflation is not determined by its initial clonal expansion. Instead, those rare T cell families that strongly dominate the chronic phase of infection show an early transcriptomic signature akin to that of established T central memory cells. Accordingly, a T cell family’s long-term dominance is best predicted by its early content of T central memory precursors, which later serve as a stem cell-like source for the antigen-driven maintenance of memory inflation.