Pro-inflammatory cytokines in the BALF of infected mice. 6-8 week old female CD1 mice were infected with 2×104 CFU of either CO92 or CO92ΔyopH. Mice were sacrificed at 24 h and 48 h post-infection and bronchoalveolar lavage was performed on their lungs. BALF was collected, filtered, and assayed by ELISA for the presence of TNF-α and IL-1β. Levels of TNF-α (A) and IL-1β (B) are significantly higher at 24 h post-infection in mice infected with Y. pestis CO92ΔyopH as compared to mice infected with wild-type CO92. ■ = mice infected with wild-type Y. pestis CO92, □ = mice infected with Y. pestis CO92ΔyopH, *** p < 0.001, ** p < 0.01, * p < 0.05, non-parametric ANOVA, these data represent 8-12 samples per data point assayed in duplicate, and are from two independent experiments.