Molecular characterization of respiratory infection with Mycoplasma bovis in feedlot cattle
Bibliographic record
Abstract
'Mycoplasma bovis' is a pathogen of the bovine respiratory disease complex (BRD) and other well-recognized clinical syndromes in cattle throughout the world. Utilization of newly developed DNA-based molecular techniques has markedly increased the understanding of the epidemiology and pathogenesis of mycoplasmal infections in humans and domestic animals. This study investigated temporal changes in the prevalence of 'M. bovis' infection, and whether 'M. bovis' concentration and 'genotype may influence the disease outcome of naturally occurring cases of respiratory disease in feedlot cattle. The study population was 130 heifers from a single feedlot in Ontario, Canada. Bronchoalveolar lavage fluid (BALF) and serum were collected upon arrival from 60 heifers. Subsequently, heifers were sampled at the onset of acute respiratory disease (up to two weeks) and 60 days post-arrival. In parallel, heifers not showing signs of respiratory disease (clinically healthy controls) were sampled at both times. Overall, 186 BALF and serum samples were collected. The prevalence of infection with M bovis based on culture increased from 1.7% on arrival to 72% and 86% at 15 and 60 days post-arrival, respectively. Similarly, serological evidence of infection increased from 33% on arrival to 74% and 100% at 15 and 60 days post-arrival, respectively. Using real-time PCR, 'M. bovis' concentrations were determined in 92 BALF samples obtained on arrival, and at 15 and 60 days post-arrival, and ranged from 1.87x10E3 to 1.03x10E8 cfu/ml. There were no significant differences in concentration between respiratory disease cases and clinically healthy controls. Using amplified-fragment length polymorphism (AFLP) and based on 95% similarity, 13 genotypes were obtained from 62 'M. bovis' field isolates. The AFLP genotypes gathered into two clusters (A and B) with 73% similarity between clusters, Cluster A comprised 74% of the strains with four distinct genotypes. Cluster B comprised 26% of the strains with nine distinct genotypes. Different AFLP genotypes were present in samples obtained from individual heifers at different sampling times. There was no association between AFLP genotype and disease status. These results suggest that ' M. bovis' concentration in BALF and AFLP genotypes do not correlate with disease outcomes in naturally occurring cases of respiratory disease in feedlot cattle.
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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) | 0.000 | 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 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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".