TABLE 8.
HI serological results compared to survival outcomes with sensitivities, specificities, PPVs, and NPVsa
| Test and HI antigen | No. of chickens with the following resultb: |
Sensitivity (%) | Specificity (%) | PPV (%) | NPV (%) | |||
|---|---|---|---|---|---|---|---|---|
| True positive | False negative | False positive | True negative | |||||
| Survival | ||||||||
| Challenge virus | ||||||||
| PWT/06 | 36 | 27 | 1 | 155 | 0.57 | 0.99 | 0.97 | 0.85 |
| SMI-HAMD/06 | 45 | 29 | 0 | 16 | 0.61 | 1.00 | 1.00 | 0.36 |
| Papua/06 | 28 | 43 | 1 | 18 | 0.39 | 0.95 | 0.97 | 0.30 |
| All viruses | 109 | 99 | 2 | 189 | 0.52 | 0.99 | 0.98 | 0.66 |
| Vaccine virus | ||||||||
| PWT/06 challenge | 62 | 1 | 113 | 42 | 0.98 | 0.27 | 0.35 | 0.98 |
| SMI-HAMD/06 challenge | 73 | 1 | 3 | 13 | 0.99 | 0.81 | 0.96 | 0.93 |
| Papua/06 challenge | 8 | 1 | 70 | 11 | 0.89 | 0.14 | 0.10 | 0.92 |
| All viruses | 143 | 3 | 186 | 66 | 0.98 | 0.26 | 0.43 | 0.96 |
| Oropharyngeal shedding of challenge virus at 2 DPC | ||||||||
| Challenge virus | ||||||||
| PWT/06 | 16 | 74 | 4 | 75 | 0.18 | 0.95 | 0.80 | 0.50 |
| SMI-HAMD/06 | 42 | 32 | 2 | 13 | 0.57 | 0.87 | 0.95 | 0.29 |
| Papua/06 | 29 | 43 | 0 | 18 | 0.40 | 1.00 | 1.00 | 0.30 |
| All viruses | 87 | 149 | 6 | 106 | 0.37 | 0.95 | 0.94 | 0.42 |
| Vaccine virus | ||||||||
| PWT/06 challenge | 88 | 1 | 47 | 32 | 0.99 | 0.41 | 0.65 | 0.97 |
| SMI-HAMD/06 challenge | 71 | 4 | 5 | 10 | 0.95 | 0.67 | 0.93 | 0.71 |
| Papua/06 challenge | 67 | 1 | 7 | 11 | 0.99 | 0.61 | 0.91 | 0.92 |
| All viruses | 226 | 6 | 59 | 53 | 0.97 | 0.47 | 0.79 | 0.90 |
The results were obtained at 3 weeks postvaccination. Sensitivity = TP/(TP + FN), specificity = TN/(FP + TN), PPV = TP/(TP + FP), and NPV = TN/(TN + FN), where TP is the number of chickens with a true-positive result, FN is the number of chickens with a false-negative result, TN is the number of chickens with a true-negative result, and FN the number of chickens with a false-negative result.
For survival, a true-positive result was seropositivity and survival, a false-negative result was seronegativity and survival, a false-positive result was seropositivity and death, and a true-negative result was seronegativity and death. For oropharyngeal shedding of challenge virus at 2 DPC, a true-positive result was seropositivity and no virus shedding, a false-negative result was seronegativity and no virus shedding, a false-positive result was seropositivity and virus shedding, and a true-negative result was seronegativity and virus shedding.