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Gene-expression profiling of calves 6 and 9 months after inoculation with Mycobacterium avium subspecies
Joel David1, Herman W Barkema2, Le Luo Guan3
1Department of Production Animal Health, University of Calgary, 3330 Hospital Drive, T2N 4N1, Calgary, AB, Canada. davij@ucalgary.ca.
Abstract:
Early detection of Johne's disease (JD) caused by Mycobacterium avium subspecies paratuberculosis (MAP) is essential to reduce transmission; consequently, new diagnostic techniques and approaches to detect MAP or markers of early MAP infection are being explored. The objective was to identify biomarkers associated with MAP infection at 6 and 9 months after oral inoculation. Therefore, gene expression analysis was done using whole blood cells obtained from MAP-infected calves. All MAP-inoculated calves had a cell-mediated immune response (IFN-γ) to Johnin PPD specific antigens, and 60% had an antibody response to MAP antigens. Gene expression analysis at 6 months after inoculation revealed downregulation of chemoattractants, namely neutrophil beta-defensin-9 like peptide (BNBD9-Like), S100 calcium binding protein A9 (s100A9) and G protein coupled receptor 77 (GPR77) or C5a anaphylatoxin chemotactic receptor (C5a2). Furthermore, BOLA/MHC-1 intracellular antigen presentation gene was downregulated 9 months after inoculation. In parallel, qPCR experiments to evaluate the robustness of some differentially expressed genes revealed consistent downregulation of BOLA/MHC-I, BNBD9-Like and upregulation of CD46 at 3, 6, 9, 12, and 15 months after inoculation. In conclusion, measuring the expression of these genes has potential for implementation in a diagnostic tool for the early detection of MAP infection.
Insights
Early detection of Johne
Area of Science:
- Veterinary Immunology
- Molecular Diagnostics
- Bovine Infectious Diseases
Background:
- Johne's disease (JD), caused by Mycobacterium avium subspecies paratuberculosis (MAP), poses a significant threat to cattle health and productivity.
- Early detection of MAP infection is crucial for controlling disease transmission and minimizing economic losses in livestock.
- Current diagnostic methods have limitations in detecting early-stage infections.
Purpose of the Study:
- To identify novel gene expression biomarkers for the early detection of Mycobacterium avium subspecies paratuberculosis (MAP) infection in cattle.
- To investigate changes in gene expression profiles in whole blood cells at 6 and 9 months post-inoculation with MAP.
- To evaluate the potential of identified gene expression markers for developing new diagnostic tools for Johne's disease.
Main Methods:
- Gene expression analysis using whole blood cells from MAP-inoculated calves.
- Quantitative PCR (qPCR) to validate the expression levels of selected differentially expressed genes.
- Assessment of cell-mediated (IFN-γ) and antibody responses to MAP antigens.
Main Results:
- Downregulation of chemoattractant genes (BNBD9-Like, s100A9, GPR77/C5a2) observed at 6 months post-inoculation.
- Downregulation of BOLA/MHC-I gene involved in intracellular antigen presentation noted at 9 months post-inoculation.
- Consistent downregulation of BOLA/MHC-I and BNBD9-Like, and upregulation of CD46 observed from 3 to 15 months post-inoculation.
Conclusions:
- Specific gene expression patterns, including downregulation of BOLA/MHC-I and BNBD9-Like, and upregulation of CD46, are associated with early MAP infection.
- These differentially expressed genes show potential as biomarkers for developing a diagnostic tool for early Johne's disease detection.
- Monitoring these gene expression changes could facilitate timely intervention and disease management strategies in cattle herds.
