Table 2.
Comparison of porcine epidemic diarrhea virus–neutralizing antibody detection by day post-inoculation (dpi): fluorescent focus neutralization (FFN) versus high-throughput neutralization test (HTNT).
| dpi* | % positive FFN† | % positive HTNT by total fluorescence ratio† |
||||
|---|---|---|---|---|---|---|
| TFR ≥ 70 | TFR ≥ 75 | TFR ≥ 80 | TFR ≥ 85 | TFR ≥ 90 | ||
| −4 | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) |
| 0 | 5 (0, 25) | 5 (0, 25) | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) | 0 (0, 17) |
| 7 | 40 (19, 64) | 60 (36, 81) | 40 (19, 64) | 35 (14, 56) | 25 (9, 49) | 10 (1, 32) |
| 14 | 95 (75, 100) | 100 (83, 100) | 100 (83, 100) | 95 (75, 100) | 95 (75, 100) | 90 (68, 99) |
| 21 | 100 (82, 100) | 100 (82, 100) | 100 (82, 100) | 100 (82, 100) | 100 (82, 100) | 100 (82, 100) |
| 28 | 95 (75, 100) | 95 (75, 100) | 95 (75, 100) | 95 (75, 100) | 95 (75, 100) | 90 (68, 99) |
| 35 | 90 (68, 99) | 90 (68, 99) | 90 (68, 99) | 90 (68, 99) | 90 (68, 99) | 85 (62, 97) |
| 42 | 100 (83, 100) | 100 (83, 100) | 100 (83, 100) | 100 (83, 100) | 95 (75, 100) | 95 (75, 100) |
Numbers in parentheses are 95% confidence intervals.
*
Sample size was 20 pigs with the exception of dpi 21 (19 pigs).
†
FFN neutralizing endpoint titers ≥1:20 were considered positive.10
‡
Sample total fluorescence intensity (TFI) was standardized as total fluorescence ratio (TFR), where TFR = 100 – ([average sample TFI × 100] ÷ average negative control TFI).