Figure 7.

Intracellular growth of F. tularensis IglE mutant strains, including (A) lipobox mutants, (B) frameshift mutants, and (C) substitution mutants within the region overlapping with FS4. J774 cells were infected by various strains of F. tularensis at an MOI of 200 for 2 h. Upon gentamicin treatment, cells were allowed to recover for 30 min after which they were lysed immediately (corresponds to 0 h; light gray bars) or after 24 h (medium gray bars) or 48 h (black bars) with PBS-buffered 0.1 % sodium deoxycholate solution and plated to determine the number of viable bacteria (log10). All infections were repeated 2 times and a representative experiment is shown. Each bar represents the mean values and the error bar indicates the SD from triplicate data sets. The asterisks indicate that the log10 number of CFU was significantly different from the parental LVS strain as determined by a 2-sided t-test with equal variance, including the Bonferroni correction for multiple pair-wise comparisons (*, P ≤ 0.05; **, P ≤ 0.01; ***, P ≤ 0.001).