<i>In vitro</i> and <i>in vivo</i> attenuation of SchuS4ΔFTT0369c, ΔFTT1676 and ΔFTT0369cΔFTT1676 mutants.

<p>(<b>A</b>) Intracellular growth of <i>F. tularensis</i> SchuS4, ΔFTT0369c, ΔFTT1676 and ΔFTT0369cΔFTT1676 strains in murine BMMs derived from C57Bl/6J mice. BMMs were infected with either strains, as described in the <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0037752#s2" target="_blank">Materials and Methods</a> section, and intracellular viable bacteria were enumerated at the indicated times points after infection. Values are means ± SD of a representative experiment performed in triplicate. Data is representative of 2 experiments of similar design. (B–C) Balb/c mice (n = 5–10/group) were infected intradermally (B) or intranasally (C) with approximately 50 CFU or 10 CFU, respectively, of the indicated strains of <i>F. tularensis</i> SchuS4. Mice were regularly monitored up to 30 days after infection and euthanized at the first sign of irreversible illness.