Figure 1.

Protective adaptive immunity against Coxiella burnetii induced by the adoptive transfer of infection-derived Coxiella-specific CD8⁺ T cells. CD8⁺ T cells from C. burnetii–infected mice were transferred to groups of 6 naive mice 28 days after infection, and each recipient mouse was challenged with 1 × 10⁶ genome equivalents of C. burnetii 24 hours after transfer. On day 14 after challenge, the mice were euthanized, and their spleens were harvested for measurement of spleen weights (A) and the detection of C. burnetii DNA by quantitative polymerase chain reaction (B). Data are expressed as the mean values (+SD) for 6 mice. *P < .05, compared with mice in which CD8⁺ T cells from Coxiella-naive mice.