Figure 3.

Complementation of the lpp mutant of Y. pestis CO92 with the htrA gene restores intracellular survival in macrophages. Intracellular survival of WT with pBR322, Δlpp mutant with pBR322, and the Δlpp with pBR322htrA was determined by infecting RAW 264.7 murine macrophages with an MOI of 1 for 45 minutes, followed by a 60-minute gentamicin wash, and plating the surviving intracellular bacteria at 4, 8, and 12 hours. The Δlpp mutant with pBR322htrA has a significant increase in percent survival compared to the Δlpp mutant with pBR322 alone, as determined by ANOVA and Holm-Sidak method.