Efficacy of Commercial Infectious Bronchitis Vaccines against Canadian Delmarva (DMV/1639) Infectious Bronchitis Virus Infection in Layers
Bibliographic record
Abstract
Vaccination is the most important way to control infectious bronchitis (IB) in chickens. Since the end of 2015, the Delmarva (DMV)/1639 strain of infectious bronchitis virus (IBV) has caused significant damage to the layer flocks in Eastern Canada. The efficacy of a combination of existing IB vaccines licensed in Canada was assessed against experimental challenge with this IBV strain. The layer pullets were vaccinated during the rearing phase with live attenuated IB vaccines of Massachusetts (Mass) + Connecticut (Conn) types followed by an inactivated IB vaccine of Mass + Arkansas (Ark) types and then challenged with the Canadian IBV DMV/1639 strain at 30 weeks of age. Protection was evaluated based on the egg laying performance, immune responses, viral shedding, and viral genome loads and lesions in IBV target organs. The vaccinated challenged hens were protected from the drop in egg production observed in the non-vaccinated challenged hens. Early (5 dpi) anamnestic serum antibody response was measured in the vaccinated challenged hens as well as a significant level of antibodies was detected in the oviduct washes (14 dpi). In contrast, hens in the non-vaccinated challenged group showed delayed (12 dpi) and significantly lower serum antibody response. Viral RNA loads were reduced in the respiratory, alimentary, and reproductive tissues of the vaccinated challenged hens compared to the non-vaccinated challenged hens. Compared to the control groups, the vaccinated challenged hens had less marked microscopic lesions in the trachea, kidney, magnum, and uterus. Our experimental model demonstrated inconclusive results for cell-mediated immune responses and viral shedding. Overall, the vaccination program used in this study minimized viral replication and histopathological changes in most IBV target organs and protected challenged hens against drop in egg production.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.002 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".