Fig. 7. Karp is more virulent than UT176 in a mouse infection model.

a Weight change over 12 days of infection. b Clinical observation score of mice 12 days post infection. This number is a composite score based on appetite, activity, and hair coat with higher numbers representing low appetite, low activity, and ruffled fur. Details provided in Supplementary Fig. 19. c Bacterial genome copy number in 100 µl blood taken from euthanized mice 12 days post infection, measured by qPCR. d The ratio of bacterial genome copy number to mouse genome copy number in lung, liver, spleen, and kidney of euthanized mice 12 days post infection, measured by qPCR. e Lesion scores of hematoxylin and eosin-stained lung, liver, spleen, and kidneys of euthanized mice 12 days post infection. Scores range from 0 to 5 with 0 representing normal tissue and 5 representing severe lesion damage. All graphs show mean and standard deviation. Statistical significance is calculated using unpaired Student t-test in GraphPad Prism software. **p ≤ 0.01 ***p ≤ 0.001 ****p ≤ 0.0001. f Images of hematoxylin and eosin-stained lung tissue of mice infected with buffer, UT176 or Karp. Scale bars = 50 µm. * indicates airway and ** indicates blood vessel. Uninfected control: airway, blood vessel, and alveoli all appear normal. UT176-infected lungs: there are diffuse thickening and infiltration of alveolar septa with a mixed population of macrophages and lymphocytes (arrows). There is also mild perivascular lymphohistiocytic inflammation (open arrow). Karp-infected lungs: there is diffuse moderate thickening and infiltration of alveolar septa with a mixed population of macrophages and lymphocytes. The airway (*) is unaffected and normal. Additional figures are shown in Supplementary Fig. 19. Mean and SD from eight individual mice is shown. Source data are provided as a Source Data file.