Related Experiment Video
Updated: May 19, 2026
Adjuvant Activity of Mycobacterium paratuberculosis in Enhancing the Immunogenicity of Autoantigens During Experimental Autoimmune Encephalomyelitis
Published on: May 12, 2023
In silico screened Mycobacterium avium subsp. paratuberculosis (MAP) recombinant proteins upregulated under stress
Ratna B Gurung1, Auriol C Purdie, Douglas J Begg
1Faculty of Veterinary Science, University of Sydney, Camden, NSW, Australia.
Abstract:
Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease (JD) in ruminants. MAP is known to enter a dormant phase outside the host, typically on soil. In vitro experiments have reported regulation of certain MAP genes when exposed to stressors similar to what is thought to produce dormancy. It is believed that in vivo regulation of dormancy genes and associated proteins by MAP may play a role in evading the host defence mechanisms and induce the host immune response against these dormancy-related proteins. Five proteins encoded by dormancy-related genes that were previously found to be upregulated under stress conditions and predicted through in silico analysis to possess immune epitopes (three hypothetical proteins and two proteins involved in fatty acid metabolism) were selected. Recombinant proteins were produced, purified and evaluated by indirect enzyme-linked immunosorbent assay (ELISA) for immunogenicity using a panel of sera obtained from sheep unexposed and exposed to MAP. The antibody levels of the exposed group were significantly higher than the unexposed group (P<0.001). Individually, the five proteins were found to discriminate between sera from sheep exposed to MAP compared to unexposed sheep. At 91% diagnostic specificity, the diagnostic sensitivity of the recombinant antigen ELISA ranged from 24% to 42% and AUC(ROC) from 0.7015 to 0.8405.
Insights
Mycobacterium avium subsp. paratuberculosis (MAP) dormancy proteins were evaluated for their immunogenicity in sheep. These proteins showed potential for diagnosing Johne
Area of Science:
- Veterinary Immunology
- Bacteriology
- Molecular Diagnostics
Background:
- Mycobacterium avium subsp. paratuberculosis (MAP) causes Johne's disease (JD) in ruminants.
- MAP can enter a dormant state outside the host, potentially evading immune responses.
- Dormancy-related gene regulation in MAP may influence host-pathogen interactions.
Purpose of the Study:
- To assess the immunogenicity of five MAP dormancy-related proteins in sheep.
- To evaluate the diagnostic potential of these proteins for Johne's disease.
Main Methods:
- Selected five MAP dormancy-related proteins (3 hypothetical, 2 fatty acid metabolism) with predicted immune epitopes.
- Produced and purified recombinant versions of these five proteins.
- Evaluated immunogenicity using indirect ELISA with sheep sera (MAP-exposed vs. unexposed).
Main Results:
- Antibody levels were significantly higher in MAP-exposed sheep compared to unexposed sheep (P<0.001).
- All five recombinant proteins individually discriminated between exposed and unexposed sheep sera.
- Diagnostic sensitivity ranged from 24% to 42% at 91% specificity, with AUC(ROC) between 0.7015 and 0.8405.
Conclusions:
- The five selected MAP dormancy-related proteins are immunogenic in sheep.
- These proteins show diagnostic potential for Johne's disease detection in ruminants.
- Further research could refine diagnostic assays using these antigens.
