FIG 11.

Proliferation of T cells isolated from WT Y. pestis CO92- and Δlpp Δpla mutant-infected mice. A total of 60 mice were i.n. challenged with a sublethal dose (250 CFU) of WT CO92 or the Δlpp Δpla double mutant (30 mice per group). At 14, 21, and 60 days p.i., T cells were isolated separately from the spleens of 5 mice in each infected group and stimulated for 3 days with APCs that had been pulsed with heat-killed WT CO92 and then γ-irradiated. Data were analyzed by using the Bonferroni correction with a one-way ANOVA, and a P value of ≤0.05 was considered significant. *, statistical significance in comparing unpulsed to pulsed T cells (P < 0.001) for both WT- and mutant-infected mice. The results represent averages from 2 independent experiments.