cbu0823 is not required for efficient intracellular replication of C. burnetii in THP-1 cells.
Intracellular replication within THP-1 macrophage-like cells of C. burnetii wildtype, 0823::Tn mutant and 0823::Tn pFLAG-CBU0823 complemented mutant strains over 7 days depicted in fold change of genome equivalents (GE) measured by qPCR for ompA. (A) Fold change in GE was plotted over 7 days as mean with error bars representing standard deviation from six independent biological replicates. There was no difference in replication between strains (p > 0.05). (B) Average vacuole area, measured in μm2 on representative immunofluorescent images of each strain and plotted as mean with error bars representing standard deviation for four of the six replicates. There was no significant difference between the three strains (p > 0.05). (C) Representative confocal immunofluorescent micrographs of THP-1 cells 3 days post-infection with C. burnetii wildtype, 0823::Tn mutant and 0823::Tn complemented mutant strains. There were no significant differences in CCV size and organism numbers between strains. Anti-Coxiella antibody (red), anti-LAMP-1 antibody (green) and DAPI (blue) were used to stain cells and white asterisks indicate CCVs. The scale bar depicts 10 μm.
