<i>gadC</i> inactivation affects intracellular survival and virulence.

<p>Intracellular replication of wild-type <i>F. novicida</i> (WT) carrying the empty plasmid pKK214 (WT/pKK(−)), of the <i>ΔgadC</i> mutant (Δ<i>gadC</i>) and complemented strain (Δ<i>gadC</i>/pKK-<i>gadC</i>), and of the Δ<i>FPI</i> mutant (Δ<i>FPI</i>), was monitored in J774.1 macrophage-like cells (<b>A</b>); in THP-1 human macrophages (<b>B</b>); and in bone marrow-derived macrophages (<b>C</b>), over a 24 h-period. Results are shown as the average of log₁₀ cfu mL⁻¹ ± standard deviation. Each experiment was performed in triplicate. **, <i>p</i><0.01 (as determined by the Student's <i>t</i>-test). Competition assays (<b>D</b>). A group of five female BALB/c mice were infected i.p. with a 1∶1 mixture of wild-type <i>F. novicida</i> and Δ<i>gadC</i> mutant strains (100 colony forming units (cfu) of each). The data represent the competitive index (CI) value for cfu of mutant/wild-type in the liver (L: black diamonds, left column) and spleen (S: black circles, right column) of each mouse, 48 h after infection. Bars represent the geometric mean CI value.