Detection of Johne’s Disease on dairy farms using different qPCR target genes for Mycobacterium avium subsp. paratuberculosis in young stock

Martins, Larissa

Detection of Johne’s Disease on dairy farms using different qPCR target genes for Mycobacterium avium subsp. paratuberculosis in young stock

dc.contributor.advisor	Barkema, Herman W.
dc.contributor.advisor	Orsel, Karin
dc.contributor.author	Martins, Larissa
dc.contributor.committeemember	De Buck, Jeroen
dc.contributor.committeemember	Pearson, Jennifer
dc.date	2023-11
dc.date.accessioned	2023-08-25T21:39:18Z
dc.date.available	2023-08-25T21:39:18Z
dc.date.issued	2023-08
dc.description.abstract	Young stock can shed Mycobacterium avium subspecies paratuberculosis (MAP) in feces, present antibody titers and transmit MAP to other young stock. However, most Johne’s disease (JD) control programs do not include young stock in MAP testing strategies, which might be one of the reasons why only a few JD control programs were able to eradicate MAP. This study aimed to include young stock in a JD testing strategy and improve diagnostic tests. A literature review conducted reported that young stock can shed MAP as early as 4 mo of age. However, due to the chronic characteristic of the disease, it was considered important to improve current diagnostic tests and develop new tests, such as phage-based and metabolomics tests. A tentative inclusion of young stock in the MAP testing strategy was evaluated based on direct fecal qPCR and ELISA every 2 mo from animals between 2-12 mo of age. A sudden rise in MAP prevalence was detected at the second sampling, 2 mo after the start of the study. Although the high MAP prevalence was explained in part by the presence of MAP infections in the herd, it was not possible to explain the specificity of the ISMAP02 gene, which raises doubts about different Mycobacterium species being detected by the same assay. Furthermore, an in depth evaluation of the main MAP target genes for qPCR assays was proposed across different sample types and MAP concentrations. Overall, all MAP target genes were able to detect samples with high MAP concentration. IS900 and ISMAP02 consistently identified MAP in all sample types. However, the genes mbtA, hspX and F57 presented issues to detect samples with mid to low MAP concentrations.
dc.identifier.citation	Martins, L. (2023). Detection of Johne’s disease on dairy farms using different qPCR target genes for Mycobacterium avium subsp. paratuberculosis in young stock (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.
dc.identifier.uri	https://hdl.handle.net/1880/116905
dc.identifier.uri	https://dx.doi.org/10.11575/PRISM/41747
dc.language.iso	en
dc.publisher.faculty	Graduate Studies
dc.publisher.institution	University of Calgary
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject	calves
dc.subject	cattle
dc.subject	diagnostic tests
dc.subject	Mycobacterium avium subsp. paratuberculosis
dc.subject	Johnes disease
dc.subject.classification	Microbiology
dc.subject.classification	Veterinary Science
dc.subject.classification	Epidemiology
dc.title	Detection of Johne’s Disease on dairy farms using different qPCR target genes for Mycobacterium avium subsp. paratuberculosis in young stock
dc.type	master thesis
thesis.degree.discipline	Veterinary Medical Sciences
thesis.degree.grantor	University of Calgary
thesis.degree.name	Master of Science (MSc)
ucalgary.thesis.accesssetbystudent	I require a thesis withhold – I need to delay the release of my thesis due to a patent application, and other reasons outlined in the link above. I have/will need to submit a thesis withhold application.