| Title |
Reactivity of recombinant SOD from Mycobacterium avium subspecies paratuberculosis in the IFN-g test. |
| Author(s) |
Beddome G,
Bruce K,
Shiell BJ,
Stiles PL,
Michalski WP*.
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| Institution(s) |
CSIRO Livestock Industries, Australian Animal Health Laboratory, Geelong, Victoria, Australia.
|
| Source |
Seventh International Colloquium on Paratuberculosis
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| Section |
3:
Immunology
|
| Abstract |
The mechanisms of immunity, pathogenesis and the molecular genetics of M. avium subspecies paratuberculosis are little known and only a few immunogenic proteins have been described. The identification and characterisation of novel antigens is of paramount importance for improved early diagnosis. Superoxide dismutases catalyse the dismutation of superoxide radical-ions and have been postulated to protect mycobacteria against oxidative stress. Secreted SODs have been identified in M. tuberculosis and M. avium subspecies paratuberculosis "in vitro" cultures. The objective of this study was to assess reactivity of Mn-containing SOD in a cell mediated immunity assay (IFNg release assay, BOVIGAMTM, CSL Animal Health Ltd). Mn-containing SOD was identified in cell free supernatants of early cultures of M. avium subspecies paratuberculosis. Purified native SOD and its recombinant version expressed in E. coli were tested in the BOVIGAMTM assay. Fractions containing both native and recombinant SOD showed weak but significant activity in a small number of animals. To determine the true reactivity of M. avium subspecies paratuberculosis SOD, recombinant protein was purified to a homogeneity level sufficient to remove residual contaminants of E. coli origin. The purified SOD showed no activity when re-tested in the BOVIGAM test.
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