Figure 3. IL-18 controls production of IFN-γ and host resistance to DENV infection.

(A) WT mice were inoculated with 10LD₅₀ of DENV-2 and at the indicated timepoints, IL-18 concentration in liver were determined by ELISA. (B–K) WT and IL-18^−/− mice were inoculated with 10LD₅₀ of DENV-2 and at the indicated timepoints, the following parameters were assessed: IFN-γ concentration in spleen (B) and serum (C), measured by ELISA; lethality rates after infection (D); platelet counts (E) and hematocrit (F) in blood; TNF-α (G) and IL-6 (H) concentration in spleen, measured by ELISA; AST activity in serum (I), measured by colorimetric assay; Liver injury, assessed by Hematoxylin & Eosin staining (seven days after infection) (J); Viral loads recovered from the spleen, by plaque assay (K). Results are expressed as mean ± SEM (except for J, expressed as median) and are representative of at least two independent experiments. N = 6 mice per group. * P<0.05 vs. NI. # P<0.05 vs. WT. NI: Not infected. ND: Not detected. dpi:day post-infection.