Extended duration of IL-7 therapy during clonal contraction enhances the LCMV-specific T-cell response. Cohorts of LCMV-Clone 13–infected mice were treated daily with either IL-7 or PBS between days 8 and 30 PI, as illustrated by the shaded area (A). At days 8, 31, 44, and 90 PI, LCMV-specific CD8 and CD4 T-cell responses were quantified by flow cytometry. (B) The kinetics of naive and activated CD8 or CD4 T cells in IL-7– and PBS–treated mice. (C) LCMV epitope-specific CD8 and CD4 T cells were quantified by staining for intracellular IFNγ. Data for each time point was obtained from an analysis of 4-5 IL-7 (●)– or PBS (▴)–treated mice and are representative of 2 experiments. *P ≤ .05; **P ≤ .005; ***P ≤ .001.