Characterization of Mycobacterium tuberculosis complex direct repeat sequence for use in cycling probe reaction

Area of Science:

• Molecular Biology
• Microbiology
• Genetics

Background:

• Cycling probe technology (CPT) offers a simple yet effective method for detecting specific nucleic acid sequences.
• The 36-bp direct repeat (DR) region is a unique genetic marker within the Mycobacterium tuberculosis complex.

Purpose of the Study:

• To develop and evaluate a diagnostic assay using CPT for the detection of the 36-bp DR region in Mycobacterium tuberculosis.
• To assess the specificity of the DR region for M. tuberculosis complex strains.

Main Methods:

• Development of a CPT assay utilizing a chimeric DNA-RNA-DNA probe targeting the 36-bp DR region.
• Specificity verification of DR probes using Southern blot hybridization across various mycobacteria.
• Sequencing of the DR region in Mycobacterium bovis 401 to design a PCR assay for estimating DR copy numbers.

Main Results:

• The 36-bp DR region was confirmed as specific to the M. tuberculosis complex.
• The CPT assay demonstrated successful detection of the DR region in synthetic targets and genomic DNA from mycobacteria.
• The DR region is present in high copy numbers and is found in M. tuberculosis strains lacking IS6110.

Conclusions:

• The 36-bp DR region is a suitable and attractive target for the detection of Mycobacterium tuberculosis.
• CPT provides a robust and specific diagnostic approach for identifying M. tuberculosis complex infections.