Molecular characterization of respiratory infection with Mycoplasma bovis in feedlot cattle
Notice bibliographique
Résumé
'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.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».