Increasing inflationary T-cell responses following transient depletion of MCMV-specific memory T cells

Murine CMV (MCMV) infection induces effector CD8(+) T cells that continue to increase in frequency after acute infection ("inflation") and are stably maintained at a high frequency, with up to 20% of the CD8(+) T-cell compartment being specific for one epitope, although the flexibility and turnover of these populations is not fully defined. Here we report that effector/memory CD8(+) T cells induced by MCMV can be paradoxically boosted following transient depletion of epitope specific CD8(+) T cells. Treatment of MCMV-infected mice with MHC-Class I-saporin tetramers led to partial (80-90%) depletion of epitope-specific CD8(+) T cells-rapidly followed by a rebound, leading to expansion and maintenance of up to 40% of total CD8(+) T cells, with minimal changes in response to a control epitope (M45). These data indicate the tight balance between host and virus during persistent infection and the functional flexibility of the "inflated" CD8(+) T cell responses during persistent infection.