Fig. 3. Scatter plot of histopathology (HP) scores in right and left lung (0 = normal; 1 = doubtful; 2, 3, 4 = increasing severity of mycoplasmal type lesions), from pigs inoculated with Hillcrest (open squares) or Beaufort strains (solid circles), or no organisms (controls; open triangles)with corresponding CT values obtained by mhp183 qPCR. One sample (not shown) with HP score 4 gave an undetermined CT value and was classified PCR negative. A CT cutpoint of 33.0 (horizontal line) was selected on the basis of HP scores where a score of 2, 3 or 4 was positive for mycoplasmal pneumonia.