TABLE 2.
Sensitivity and specificity of cytokine tests estimated by ROC analysisa
| Effect | Diagnostic antigen | Area under ROC curve | Sensitivity (%) | 95% CI (%) for sensitivity | Specificity (%) | 95% CI (%) for specificity | Cutoff value (ng/ml) |
|---|---|---|---|---|---|---|---|
| Differentiate M. bovis-infected cattle from NC | PPD-B-stimulated IL-8 | 0.9662 | 92.86 | 80.52–98.50 | 94.74 | 73.97–99.87 | >32.57 |
| 92.86 | 80.52–98.50 | 100 | 82.35–100.0 | >43.05 | |||
| CE-stimulated IL-8 | 0.9561 | 85.71 | 71.46–94.57 | 94.74 | 73.97–99.87 | >21.9 | |
| 85.71 | 71.46–94.57 | 100.0 | 82.35–100.0 | >29.42 | |||
| PPD-B-stimulated IP-10 | 0.9500 | 52.38 | 36.42–68.00 | 95 | 75.13–99.87 | >1.992 | |
| 52.38 | 36.42–68.00 | 100 | 83.16–100.0 | >2.045 | |||
| PPD-B-stimulated IL-17A | 0.8464 | 28.57 | 15.72–44.58 | 95 | 75.13–99.87 | >1.767 | |
| 28.57 | 15.72–44.58 | 100 | 83.16–100.0 | >2.061 | |||
| Differentiate bTBPCR-P and bTBPCR-N | PPD-B-stimulated CRP | 1.000 | 100 | 83.89–100.0 | 95.24 | 76.18–99.88 | >701.3 |
| 100 | 83.89–100.0 | 100 | 83.89–100.0 | >794.8 | |||
| Unstimulated IL-8 | 0.8322 | 52.38 | 29.78–74.29 | 100.0 | 83.89–100.0 | <4.088 | |
| 52.38 | 29.78–74.29 | 95.24 | 76.18–99.88 | <4.648 | |||
| PPD-B-stimulated AGP | 0.7732 | 52.38 | 29.78–74.29 | 95.24 | 76.18–99.88 | <49,925 | |
| 42.86 | 21.82–65.98 | 100.0 | 83.89–100.0 | <46,732 | |||
| Serum SAA | 0.7914 | 38.10 | 18.11–61.56 | 95.24 | 76.18–99.88 | >12,082 | |
| 38.10 | 18.11–61.56 | 100.0 | 83.89–100.0 | >12,495 |
The cutoff values for the PPD-B-stimulated IL-8, IP-10, and IL-17A ELISAs were obtained using 19 healthy cattle and 42 M. bovis-infected cattle. The cutoff values for the PPD-B-stimulated CRP, PPD-B-stimulated AGP, unstimulated IL-8, and serum SAA ELISAs were obtained using 21 bTBPCR-P and 21 bTBPCR-N. CI, confidence interval. The PPD-B-stimulated IL-8 ELISA showed a higher area under the ROC curve (AUC = 0.9662) and was better than the CE-stimulated IL-8, PPD-B-stimulated IP-10, and IL-17A ELISAs at differentiating M. bovis-infected cattle from NC. The PPD-B-stimulated CRP ELISA was better than the unstimulated IL-8, PPD-B-stimulated AGP, and serum SAA ELISAs at differentiating bTBPCR-P and bTBPCR-N. The specificity for each diagnostic antigen was set at nearly 95% or 100%, and the sensitivity, area under the ROC curve, and cutoff value were calculated and are shown.