FIGURE 3.

Stimulation through TLR4 but not IFN-β partially restores IL-1β suppression by F. tularensis (Ft) LVS. Macrophages were stimulated with E. coli LPS and infected with 100 m.o.i. of F. tularensis LVS (A) or F. novicida (B). The macrophages were treated with recombinant IFN-β and infected with F. tularensis LVS (C) or F. novicida (D). The IL-1β levels were measured in the culture supernatants at 6 and 24 h post-infection. The results are representative of at least two to three independent experiments. The data were analyzed by ANOVA with Tukey-Kramer post test, and a cut-off p value of 0.05 or less was considered significant. **, p < 0.01; ***, p < 0.001.