A quantitative analysis of tissue samples collected from dairy calves infected with Mycobacterium avium subsp. paratuberculosis
Notice bibliographique
Résumé
In an infection trial 16 Holstein-Friesian bull calves were raised in a biosecurity level 2 facility at the University of Calgary. Calves were randomly allocated into two groups and euthanized at two and four months. In each group, six calves were infected with a library of Transposon (Tn) mutants created from a MAP strain named A1-157 located in the dominant clade of isolates obtained from Canadian farms. Two calves in each group received the wildtype (WT) A1-157 strain serving as positive infection ‘controls’. After euthanasia, from each calf tissue samples from various anatomical locations were collected. For this study, the distal jejunum, distal jejunum lymph nodes, the spleen and inguinal lymph nodes were used. Using a self-developed protocol DNA from MAP was isolated from these samples in triplicates. A qPCR procedure targeting the F57 and IS900 loci was performed. qPCR results were then analysed with the help of a F57 plasmid standard curve to translate real time fluorescence measurements to bacterial log copy numbers.\nAll calves, library and WT euthanized at two or four months after inoculation, were successfully infected with MAP. F57 Ct values were all below 40 indicating that the tissues sampled were positive. Significant differences in log copy numbers between calves infected with the library of mutants euthanized at two and four months of age could not be detected in any of the tissues. As for the difference between wildtype calves euthanized at two and four months only in the spleen a significant difference in log copy numbers was noted with the four month old calves being less frequently positive (P=0,01). Furthermore, there was a significant difference in log copy numbers between library and wildtype calves euthanized at two and four months for the distal jejunum and jejunal lymph nodes. Log copy numbers were approximately equally divided for all four tissues in calves euthanized at two months, but in the calves euthanized at four months the distal jejunum and jejunum lymph nodes showed higher log copy numbers. CFU counts from MAP grown on agar were compared to CFU expected calculated from qPCR results of the same tissues. There was up to a 3-fold difference between the CFUs grown and expected in the jejunum and a 20-fold difference for the jejunal lymph nodes. We conclude, therefore, that both the WT and library calves were successfully infected and that the protocol to isolate and quantify MAP worked. Furthermore, more MAP was present in the tissues than grown on the agar plates.
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 machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,001 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,001 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,001 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,001 | 0,001 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,002 | 0,001 |
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 source (Gemma direct ou Codex distillé), 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 ».