Table 3.
Validation parameters for the sheep indirect ELISAs. C. pseudotuberculosis recombinant proteins PLD, CP40, a combination 1:1 of these two proteins, and PknG were used as antigens. The conditions for the ELISA procedures were those that presented the best discrimination between the positive and negative serum sample pool optical densities (ODs)
| Parameter | PLD | CP40 | PLD + CP40 | PknG |
|---|---|---|---|---|
| Positive control | 78 | 78 | 78 | 78 |
| Negative control | 82 | 82 | 82 | 82 |
| False positives | 1 | 22 | 6 | 38 |
| False negatives | 7 | 19 | 4 | 26 |
| Cut‐off (Optical density) | 0.144 | 0.306 | 0.261 | 0.166 |
| Sensitivity (%) | 91 | 75.6 | 94.8 | 66.7 |
| Specificity (%) | 98.7 | 73 | 92.6 | 53.6 |
| Accuracy (%) | 96.5 | 80.1 | 98 | 60.9 |
| Positive predictive value (%) | 98.6 | 72.8 | 92.5 | 57.7 |
| Negative predictive value (%) | 92 | 75.9 | 95 | 62.8 |
| Repeatability positive control (%) | 99.9 | 99.8 | 99.8 | 99.9 |
| Repeatability negative control (%) | 99.9 | 99.9 | 99.9 | 99.9 |
| Repeatability serum with OD result close to cut‐off (%) | 99.9 | 99.9 | 99.9 | 99.9 |
| Reproducibility (%) | 100 | 100 | 100 | 100 |
| Kappa | 0.900 | 0.488 | 0.875 | 0.215 |