FIGURE 3.

Internalization and intracellular survival of S. Typhimurium 14028s and defined mutants in D. discoideum. Competition assays were used to determine the intracellular survival of S. Typhimurium mutants ΔaroA (purple), ΔinvA (green), ΔssaD (red) ΔclpV (blue), ΔphoPQ (orange), ΔphoN (light blue), and ΔwaaL (yellow). (A) Internalization relative to the wild-type strain calculated as (CFU_mutant/CFU_WT)_t=0/(CFU_mutant/CFU_WT)_inoculum and expressed as log₁₀. (B) Competitive index (CI) between a defined mutant and the wild-type strain calculated at each time point as (CFU_mutant/CFU_WT)_{t = x}/(CFU_mutant/CFU_WT)_t=0 and expressed as log₁₀. (C) Population of viable amoebae at each time point expressed as cells/mL. Graphics shows the mean of at least three independent assays ± SEM. Statistical significance was determined using a two-tailed Student’s t-test (^∗P < 0.05, ^∗∗P < 0.005, ^∗∗∗P < 0.001).