FIG. 1.

Deletion of ompX extends the time to death in Y. pestis CO92 pneumonic infections. Groups of BALB/c mice (n = 8/group) were challenged intranasally with 10 LD₅₀ (A) or 100 LD₅₀ (B), doses established previously for WT Y. pestis CO92 (LD₅₀ = 2 × 10⁴ CFU). The animals were monitored for morbidity and mortality through 10 days postchallenge. The graph presents survival of the animals challenged with WT, ΔompX, or ompX⁺/ΔompX strains. A difference in survival times for animals infected with the ΔompX strain was observed (log rank test, P < 0.001). Data represent combined survival numbers from two experiments performed on separate days.