Fig 2.
Correlation between IP-10 and IFN-γ responses (mRNA) to M. bovis PPD. PBMC were isolated from cattle receiving M. bovis (104 CFU) by aerosol at 0, 14, 28, 57, 92, and 113 days relative to challenge and stimulated with M. bovis PPD or medium alone (i.e., no stimulation), and RNA was harvested for measurement of IP-10 and IFN-γ gene expression using the 2−ΔΔCT method with nonstimulated cells as the calibrator. Data represent IP-10 (y axis) versus IFN-γ (x axis) responses for each individual animal at each time point as relative fold change in mRNA expression (n = 42 [7 animals × 6 time points]; results from one animal missing for the 57-day time point) (r = 0.87, P < 0.001).