Fig 3. Infection with 667 is less virulent than Erdman.

The bacterial burden is measured by CFU from lung (A) or spleen (B) homogenates from Erdman (filled) or 667 (open) infected C57BL/6J at different timepoints post infections. CFU data were compiled from 13 (lung) or 6 (spleen) independent experiments, from 4 to 30 weeks post infections. (C) The survival of C57BL/6 mice after Erdman (solid) or 667 (dashed) infection, which is one of two independent results with similar results. In this experiment, the d1 CFU was 158 (667) or 55 (Erdman). (D-E) A barcoded pool of clinical Mtb isolates was administered intravenously to C57BL/6J (black) or RAG1 KO (red) mice, and 4–8 mice of each strain were harvested for lungs and spleens to recover bacteria at 1 (circle), 14 (triangle), and 21 (square) days post infection. (D) The pseudo CFU of 667 and Erdman in spleen were determined by the relative abundance of the respective Mtb strains multiplied by total CFU in the spleen. (E) CFU fold-change (versus d1 CFU) of 667 or Erdman abundance in the spleen was compared between C57BL/6J (black) and RAG1 KO (red) mice. (F) CFU fold-change (versus d1 CFU) of 667 (open) vs. Erdman (closed) in the spleens of C57BL/6J (black) and RAG1 KO (red) mice. Statistical significance of survival curves (C) was determined by log-rank (Mantel-Cox) test; p value is shown. Statistical significance of CFU fold-change (D, E, F) were analyzed by a two-way ANOVA with Tukey (D) or Sidak’s (E, F) multiple comparison test. p values are indicated by asterisks: **, p<0.01, ***, p<0.001, ****, p<0.0001. Not all comparisons are shown for clarity.