Duration of immunity to experimental infection with bovine respiratory syncytial virus following intranasal vaccination of young passively immune calves
Bibliographic record
Abstract
OBJECTIVE: To determine whether a combination modified-live bovine respiratory syncytial virus (BRSV) vaccine could stimulate protective immunity in young BRSV-seropositive calves following intranasal administration and determine the duration of clinical immunity. DESIGN: Controlled challenge study. Animals-84 dairy calves (3 to 11 days old). PROCEDURES: Responses to BRSV challenge of seronegative calves vaccinated under licensing trial conditions were compared with those of seropositive calves 2 times after vaccination. In experiment 1, young BRSV-seronegative calves were vaccinated intranasally with a minimum immunizing dose of BRSV and challenged with BRSV approximately 7 weeks later. In experiments 2 and 3, young BRSV-seropositive calves were vaccinated intranasally with a commercially available combination modified-live virus vaccine containing the commercial dose of the BRSV fraction and challenged with BRSV 9 weeks or approximately 14 weeks later, respectively. RESULTS: In experiments 1 and 2, BRSV-vaccinated calves had significantly higher Pao2, significantly fewer lung lesions, and significantly lower mortality rate than did unvaccinated calves subsequent to BRSV challenge. In contrast, in experiment 3, there were no differences in Pao2, lung lesions, or mortality rate between vaccinated and control calves after BRSV challenge approximately 14 weeks after vaccination. Protected calves in experiment 1 consistently had significant anamnestic mucosal and systemic antibody responses after challenge, whereas in experiments 2 and 3, antibody responses after challenge were more variable. CONCLUSIONS AND CLINICAL RELEVANCE: A combination BRSV vaccine administered intranasally to young calves induced protective immunity in the presence of maternal antibodies. The duration of immune responses induced by intranasal vaccination was short (≤ 4 months). Boosting immunity iatrogenically, or by natural exposure, is probably required to obtain optimal responses to neonatal intranasal vaccination.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| 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 source (direct Gemma or distilled Codex), 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".