Fig. 4: Disruption of B. dolosa LPS O-antigen expression leads to tradeoffs in lung versus spleen infection in vivo.
From: De novo mutations mediate phenotypic switching in an opportunistic human lung pathogen
a Mice were infected with a 50:50 mixture of O-antigen-intact and disrupted phenotypes, with one B. dolosa strain marked with a lacZ cassette conferring blue colony color on X-gal-containing Bcc-selective agar. Lungs and spleens were excised to determine the bacterial load of O-antigen-intact and O-antigen-disrupted strains. Two trials of this experiment were performed for each of three near-isogenic pairs. The mean fraction of O-antigen-disrupted bacteria in mouse spleens and lungs is shown with error bars representing 95% confidence intervals. The O-antigen-disrupted fraction is higher in spleens relative to lungs for all pairs (P < 10−3, two-sided paired t test). Macrophages were infected for 2 hours with near-isogenic B. dolosa strains with and without an O-antigen-disrupting mutation and then incubated for 2 hours with kanamycin, which kills extracellular bacteria. The number of intracellular bacteria is compared to the total bacteria obtained from an identical culture without kanamycin treatment, revealing an advantage for O-antigen-disrupted bacteria within macrophages (P < 0.03, two-sided Wilcoxon rank sum). Bars represent averages across four concurrent technical replicates. a was created in BioRender. Poret, A. (2025) https://BioRender.com/ig94dd7.
