Early Detection of Circulating Antigen and IgM-Associated Immune Complexes during Experimental Mycobacterium bovis
Konstantin P Lyashchenko1, Rena Greenwald2, Alina Sikar-Gang2
1Chembio Diagnostic Systems, Inc., Medford, New York, USA klyashchenko@chembio.com.
Insights
Early detection of Mycobacterium bovis antigen in cattle serum, bound to IgM, offers potential for improved bovine tuberculosis diagnostics before antibody seroconversion.
Area of Science:
- Veterinary Immunology
- Bacteriology
- Diagnostic Development
Background:
- Bovine tuberculosis (BTB) remains a significant global animal health challenge.
- Current diagnostics for BTB often rely on detecting host antibody responses, which can be slow to develop.
- Early detection of Mycobacterium bovis infection is crucial for effective disease control.
Purpose of the Study:
- To investigate the presence and characteristics of circulating Mycobacterium bovis antigen in experimentally infected cattle.
- To evaluate the potential of antigen detection for early immunodiagnostics of bovine tuberculosis.
- To explore the association of antigen with specific immunoglobulin classes and potential clearance routes.
Main Methods:
- Utilized dual-path platform (DPP) technology for antigen capture immunoassays.
- Employed rabbit polyclonal antibodies targeting M. tuberculosis complex-specific epitopes.
- Analyzed antigen presence in serum, bile, and urine, and its binding to IgM and IgG.
Main Results:
- Circulating Mycobacterium bovis antigen was detected in cattle serum using DPP technology.
- Antigen was primarily bound to IgM in early infection stages, not IgG.
- Antigen was also found in bile and urine, suggesting clearance pathways.
- Antigen detection preceded detectable antibody seroconversion by months.
Conclusions:
- Early detection of M. bovis antigen in cattle serum is feasible using antigen capture immunoassays.
- The association of antigen with IgM suggests its role in early infection and persistence.
- This approach shows promise for developing improved, earlier immunodiagnostics for bovine tuberculosis.
Abstract:
The presence of circulating antigen in cattle experimentally infected with Mycobacterium bovis was demonstrated using dual-path platform (DPP) technology. The antigen capture immunoassays employed rabbit polyclonal antibody recognizing predominantly M. tuberculosis complex-specific epitopes and were able to detect soluble substances and whole cells of mycobacteria. The antigen found in serum appeared to be mostly bound to IgM, but not to IgG, within the immune complexes formed at early stages of M. bovis infection. The antigen was also detected in bile and urine, indicating possible clearance pathways. The data correlation analyses supported the idea of the role of IgM responses in antigen persistence during M. bovis infection. The antigen was detectable in serum months prior to detectable antibody seroconversion. This proof-of-concept study suggested the potential for improved immunodiagnostics for bovine tuberculosis.
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