The Rv2807 target gene: a determining factor to directly detect Mycobacterium bovis from suspected bovine tuberculosis lesions
Bibliographic record
Abstract
Bovine tuberculosis (bTB) is a zoonosis caused by Mycobacterium bovis, a species belonging to the Mycobacterium tuberculosis complex (MTC) group. Direct bTB diagnosis from suggestive lesions can be performed by nested q-PCR targeting the Rv2807 gene present in the MTC group, as well as the TbD1 gene, present in M. bovis. In this context, the aim of the present study was to assess the importance of considering positive MTC results for the Rv2807 target gene obtained through the nested real time polymerase chain reaction (nested q-PCR) applied to samples obtained directly from suspected bTB lesions. A total of 174 samples of suggestive bTB caseous lesions were obtained during cattle slaughter in slaughterhouses in the state of Mato Grosso, Brazil. DNA was extracted from the lesions and nested q-PCR was performed to detect both MTC and M. bovis. Both samples positive for the Rv2807 (41/174) and TbD1 (29/174) were submitted to bacterial culturing (23/41), and the DNA of the isolates (23) was extracted and submitted again to nested q-PCR. The Rv2807 gene (MTC) was previously amplified by nested q-PCR directly from the lesions, although the TbD1 gene specific for M. bovis was not amplified previously in four of the successfully isolated samples (4/23), only following isolation, and only the Rv2807 gene was amplified before and after isolation. In conclusion, the target gene Rv2807(MTC) exhibited higher positivity in the analyzed samples compared to the TbD1 gene (M. bovis).
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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 | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.001 |
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".