Figure 6.

Complementation of the nadB::Tn mutant with a plasmid expressing the inactive R275L-NadB did not rescue the intracellular growth defect in either HeLa cells (A) or THP-1 cells (B). Intracellular replication of C. burnetii was measured over 7 days. The fold increases in GEs relative to the inoculum were determined by ompA-specific qPCR and are represented here as the means ± S.D. of three independent infections at days 1, 3, 5, and 7 postinfection. Both the nadB mutant (closed squares) and the R275L complemented nadB mutant (closed triangles) were significantly reduced in growth in HeLa cells compared with C. burnetii NMII WT (closed circles) at days 5 and 7 (p < 0.05, paired t test) and at all time points in THP-1 cells (p < 0.05, paired t test). Open squares represent the original complemented nadB mutant.