Study of shedding patterns of Mycobacterium avium subspecies paratuberculosis in feces, milk, and colostrum of dairy cows and the development of novel early detection methods for Johne's Disease
Bibliographic record
Abstract
The focus of this research was to improve Mycobacterium avium subsp. paratuberculosis (MAP) control and management programs through increased understanding of the diagnostic detection ability of common pathogen and antibody assays over seasons and lactation stages, as well as through the novel use of MAP-specific proteins and a cell-transport media for early diagnostic potential.\nSolid and broth cultures, real-time PCR (qPCR), and ELISA diagnostic tests were used to assess a 12-month period of fecal, milk, and colostrum sampling from 51 MAP-infectious dairy cows and 52 consistently test-negative cows from four farms in New Brunswick and three farms in Prince Edward Island, Canada.\nFor all fecal, milk, and colostrum samples, improved detection ability for MAP was observed with qPCR over culture methods. The bacteria was four times more likely to be detected in feces than in milk with the same testing method in both sample types, but MAP was two times more likely to be detected in feces than in colostrum with qPCR testing. Milk ELISA detected antibodies three out of ten sampling times, but detection ability improved as fecal shedding or host age increased.\nSeasonal effects were observed for qPCR and milk ELISA results. Higher detection ability occurred in winter and spring for fecal qPCR, in summer for milk qPCR, and in winter for milk ELISA. Summer held the best agreement between milk and fecal samples collected within the same month. In addition, milk ELISA showed better detection levels in late lactation animals. MAP virulence proteins, including protein tyrosine phosphatase A (PtpA) and protein kinase G (PknG), were evaluated for use in a novel ELISA antigen-coating in milk and serum samples and as antigens for the interferon-gamma (IFN-γ) assay. In addition to the previous samples, extra serum and colostrum samples from cows from the same herds, and serum samples from cows from a test-negative herd were assessed. Improved detection of PtpA was seen in milk and PknG in colostrum, but results were inconsistent and variable. Production of IFN-γ was detected in interleukin-12 (IL-12) p40-potentiated PtpA and PknG whole blood samples. However, small sample size, low protein availability, and inconsistent results in the infected (two cows) and non-infected (two cows) animals biased the apparent benefit of these virulence proteins.\nIn addition, a novel cell transport media was assessed for improving the utilization of the IFN-γ assay. Whole blood samples from ten healthy cows were each divided into test and control samples, stimulated with the mitogens pokeweed and concanavalinA (ConA), as well as IL-12 p40, on days 1, 5, and 8 post-sampling. Functional immune response was assessed through IFN-γ production (ELISA) and mononuclear cell viability (propidium-iodide flow cytometry). Addition of the transport media improved ConA-dependent IFN-γ secretion and improved mononuclear cell viability up to eight days post-collection.\nImproving our knowledge of factors affecting the interpretation of diagnostic assays could benefit Johne’s disease management programs through more effective diagnostic strategies and increased producer participation. Results of this research support the use of qPCR in a Johne’s herd control program, particularly to help minimize MAP exposure to calves. Furthermore, a simple method to extend white blood cell viability in vitro can enhance the practicality of the IFN-γ test as another means of detecting MAP exposure and future risk of MAP infection and transmission within a herd.
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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 | 0.001 | 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".