. 2004 Sep;72(9):4973–4984. doi: 10.1128/IAI.72.9.4973-4984.2004

TABLE 2.

PhoP is important for survival of Y. pseudotuberculosis and Y. pestis in macrophages

Strain	Survival index^a
IP2666cphoPΔ/MMB67EH	0.049
IP2666cphoPΔ/PhoP^KIM	0.827
KIM10⁺phoPΔ/MMB67EH	0.005
KIM10⁺phoPΔ/PhoP^KIM	0.738
32777phoP::kan/MMB67EH	0.087
32777phoP::kan/PhoP^KIM	0.811

J774A.1 cells were infected with parental strains (IP2666c, 32777, KIM10⁺) or the phoP mutant strains at an MOI of 5 (IP2666c, 32777) or 2 (KIM10⁺). Bacterial cultures were grown at 28°C prior to infection. IPTG (500 μM) was present in the medium throughout the infection to induce phoP expression. CFU counts were determined after 0.25 or 25 h of infection as described in Materials and Methods. The values are values from a representative experiment with duplicate wells. The survival index was calculated from the CFU counts by using the following formula: (CFU of mutant at T₂₄/CFU of parent at T₂₄)/(CFU of mutant at T_0.25/CFU of parent at T_0.25), where T₂₄ and T_0.25 are 24 and 0.25 h after infection, respectively.