FIG 7.

Tbet plays a role in vaccine protection that partially depends on Th1 CD4⁺ T cells. Tbet-deficient (Tbet KO), Stat6-deficient (Stat6 KO), RORγt-deficient (RORγt KO), CD4 KO, and WT C57BL/6 mice were vaccinated s.c. with 10 μg of PIV and challenged i.p. with 1 × 10⁷ genomic copies of C. burnetii NMI 28 dpv. Mice receiving Alhydrogel adjuvant alone served as unvaccinated controls. (A) The relative body weight was determined throughout the infection. Splenomegaly (B) and splenic bacterial burden (C) were evaluated at 14 dpi to compare protection. The results are expressed as the percent splenomegaly, i.e., (spleen weight/body weight) × 100. The bacterial burden was determined by real-time quantitative PCR (qPCR) and is expressed as log₁₀ C. burnetii com1 gene copy numbers. Each experimental group includes five mice, with error bars representing the standard deviations from the mean. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001 (as determined by two-way ANOVA with Dunnett’s multiple-comparison test [A] or one-way ANOVA with Tukey’s multiple-comparison test [B and C]).