Table 2.
Serological response and protection conferred by the vaccine program in place against a genotype VII lethal challenge
| Group | Vaccination protocol (genotype VII Venezuelan isolate challenge virus; n = 21 birds) | No. of birds with positive results/total no. of birds tested (% protection) | Mean ELISA titera |
|||||
|---|---|---|---|---|---|---|---|---|
| NDV |
IBDV |
|||||||
| Day 14 | Day 21 | Day 28 | Day 14 | Day 21 | Day 28 | |||
| G01 | Exptl farm (live/killed day 1 + live day 7 and 17) | 2/21 (90.5) | 856a | 1,713a | 2,384a | 573a | 10,506a | 7,295a |
| G02 | Commercial farm (live/killed day 1 + live day 7 and 17) | 9/21 (57) | 908a | 89b | 1,356b | 160b | 141b | 1,489b |
| G03 | Exptl farm (challenged, nonvaccinated) | 21/21 (0) | 140b | 53b | 22c | 134b | 77b | 52c |
Serology data are presented as mean titers. Group means were analyzed by ANOVA with Tukey's multiple-comparison test. Different letters within columns indicate significant differences (P < 0.05) between antibody levels. ELISA antibody titers were 2,343 and 1,043 for experimental and commercial farms, respectively, indicating a significant (P < 0.05) decrease in the level of humoral immunity provided by the NDV vaccination program in the birds raised in the commercial set. For IBDV, the antibodies measured in the commercial farm suggest an early IBDV field infection with antibody levels of 10,506 and 7,295 at 21 and 28 days, respectively. In the group reared under controlled conditions, the IBDV antibody level was 1,489.