Recent thymic emigrants preferentially undergo memory inflation after persistent infection.

Area of Science:

• Immunology
• Virology
• Cellular Biology

Background:

• Cytomegalovirus (CMV) infection causes 'memory inflation,' a continuous accumulation of antigen-specific memory CD8+ T cells during latency.
• The mechanisms generating and sustaining this expanding CD8+ T cell pool remain unclear.

Purpose of the Study:

• To investigate the dynamics of CD8+ T cell recruitment into the memory pool during persistent CMV infection.
• To understand the role of recent thymic emigrants (RTEs) in memory inflation.

Main Methods:

• Utilized murine cytomegalovirus (MCMV) as a model for persistent infection.
• Employed fate-mapping mice to track CD8+ T cell dynamics and recruitment into the memory pool.

Main Results:

• Neonatal CMV exposure expands recent thymic emigrants (RTEs), which are maintained in the long-lived memory compartment.
• CD8+ T cells generated post-infection contribute minimally to memory inflation.
• RTEs differentiate into effector memory cells, while mature T cells favor central memory cells.
• Preferential recruitment of RTEs into the effector memory pool occurs in both neonatal and adult CMV infections.

Conclusions:

• Persistent CMV infection expands the RTE population.
• The timing of CMV infection (neonatal vs. adult) determines which RTEs are 'locked in' to the memory pool.
• This study elucidates the distinct contributions of RTEs and mature T cells to CMV-induced memory inflation.