Antibody mediated depletion of TNF-α or IL-1β enhances virulence of CO92Δ yopH. CD-1 mice were treated with cytokine depleting antibodies or isotype control antibodies 1 day prior to infection and then every third day for the course of the experiment. Animals were then infected IN with 2 X104 CFU of CO92 or CO92ΔyopH and monitored for survival for 10 days. A) Depletion of IL-1β has no effect. B) Depletion of TNF-α causes 10% mortality. C) Depletion of both TNF-α and IL-1β has a synergistic effect leading to 30% mortality. D) Depletion of IL-1β during CO92 infection has no effect. E) Depletion of TNF-α during CO92 infection has no effect. Data is combined from two independent experiments with 10 mice per group.