FIG 4.

S. pneumoniae D39 ΔOPT does not show increased resistance to N-terminal CXCL10 relative to S. pneumoniae D39, and N-terminal CXCL10 exhibits decreased antimicrobial activity compared to full-length CXCL10 for S. pneumoniae D39. A fluorescence-based antimicrobial assay was performed with full-length CXCL10 (left 4 bars) or N-terminal CXCL10 (aa 1 to 54) (right 6 bars) with S. pneumoniae D39 (IU1690) or S. pneumoniae ΔOPT (IU11919) in NPB. Each bar represents the mean ± SEM of results of 3 independent experiments (unless otherwise noted). The statistical significance of the results of comparisons between strains at the same concentration was determined using the Mann-Whitney U test (except for 3 μM CXCL10, where n = 2). Asterisks denote difference between strains at the same concentration. **, P < 0.01; ns, not significant.