FIG 8.

Eosinophils contribute to antibody isotype switching in late PIV responses. WT and ΔdblGATA mice were vaccinated s.c. with 10 μg of PIV 4 weeks prior to i.p. challenge with 1 × 10⁷ C. burnetii NMI bacteria. (A) Relative body weight was measured throughout infection. Splenomegaly (B) and bacterial burden in the spleen (C) were evaluated at 14 dpi to assess disease severity. (D) Serum IFN-γ levels were quantified at 14 dpi by cytokine-specific ELISA. C. burnetii NMI-specific serum IgM and IgG levels were measured weekly until 28 dpv (E) as well as at 14 dpi (F). Results are expressed as percent splenomegaly [(spleen weight/body weight) × 100]. Bacterial burden was determined by qPCR and is expressed as log₁₀ C. burnetii com1 gene copy numbers. Each experimental group includes 4 mice, with error bars representing the standard deviations from the means. *, P < 0.05; **, P < 0.01; ***, P < 0.001; ****, P < 0.0001, as determined by two-way ANOVA with Dunnett’s multiple-comparison test (panels A and D) or by one-way ANOVA with Tukey’s multiple-comparison test (panels, B, C, and E).