FIG 5.

Riboswitch-mediated control of FTN_0818 facilitates intracellular replication. RAW264.7 murine macrophages were infected with the indicated F. novicida strains at an MOI of 20:1 in the presence of 0, 1, or 2 mM theophylline. Macrophages were lysed at 30 min and 24 h postinfection and plated to enumerate the intracellular CFU. Fold replication was calculated by dividing the number of CFU at 24 h postinfection by the number of CFU at 30 min. Bars represent the average fold replication of the strains, and error bars depict the standard deviations. The data are representative of four independent experiments. Asterisks indicate a significant difference in fold replication from that of the ΔFTN_0818 mutant strain in the presence of the indicated concentration of theophylline (***, P < 0.0005). WT, wild type.