Novel potential diagnostic test for Mycobacterium tuberculosis complex using combined immunomagnetic separation (IMS)...

Area of Science:

• Microbiology
• Molecular Diagnostics
• Immunology

Background:

• Tuberculosis (TB) diagnosis traditionally relies on slow culture methods.
• Rapid and accurate detection of Mycobacterium tuberculosis complex (MTC) and Mycobacterium bovis is crucial for effective treatment and control.
• Existing molecular methods may lack simultaneous identification capabilities or require extensive sample preparation.

Purpose of the Study:

• To develop and validate a rapid diagnostic assay using immunomagnetic separation combined with PCR with confronting two-pair primers (IMS-PCR-CTPP).
• To detect the Mycobacterium tuberculosis complex (MTC) in sputum specimens.
• To simultaneously identify Mycobacterium bovis within MTC detections.

Main Methods:

• Development of monoclonal antibody (mAb) against mycobacterial antigen 85B (Ag85B) coupled with magnetic particles for immunomagnetic separation (IMS).
• Application of IMS for specific separation of Mycobacterium species from sputum.
• Integration of IMS with PCR with confronting two-pair primers (PCR-CTPP) targeting the lep B gene for MTC detection and M. bovis identification.

Main Results:

• The mAb demonstrated effective binding to Ag85B in both recombinant and native forms.
• The IMS-PCR-CTPP assay was tested on 133 sputum samples.
• The method achieved a sensitivity of 89.9% and a specificity of 88.6% compared to the gold standard culture method.

Conclusions:

• The IMS-PCR-CTPP method offers a significant reduction in TB diagnosis time, from months to a single day.
• This technique is suitable for the investigation of MTC and the epidemiological study of Mycobacterium bovis in sputum.
• The combined IMS and PCR-CTPP approach provides a novel tool for TB diagnosis, particularly beneficial for resource-limited settings with a high TB burden.