Fig. 1

Brugia pahangi worms exposed to higher concentrations of antibiotics maintained higher Wolbachia titers. Female and male worms were treated with 6-point serial dilutions of doxycycline, minocycline, tetracycline and rifampicin in vitro for 6 days and assessed for worm motility and Wolbachia titers (see also Fig. S1 and Table S1 for statistical significance). For female worms, higher concentrations of antibiotics inhibited worm motility, but surprisingly Wolbachia titers did not decrease. Male worms were similarly affected except for those treated with tetracycline, which did not show a positive correlation between Wolbachia titers and antibiotic concentration. Wolbachia titers were measured by qPCR as a ratio of wsp/gst (shown as medians with 95% confidence intervals); antibiotic concentrations are in µM. The percent differences in wsp/gst ratios as compared to DMSO controls are shown below each antibiotic concentration. Negative percentages signify a decrease in Wolbachia titers, and positive percentages indicate titers that were higher than controls. Percent inhibition of worm motility is also shown below each antibiotic concentration: 0% inhibition indicates that worms were as motile as controls, and 100% inhibition indicates that the worms were not motile. There was an inverse relationship between worm motility and wsp/gst ratio (r ≤ −0.5), except for males treated with tetracycline, which did not show this inverse relationship