Expression and Purification of Recombinant Mycobacterium Tuberculosis (TB) Antigens, ESAT-6, CFP-10 and ESAT- 6/CFP-10 and Their Diagnosis Potential for Detection of TB Patients

BACKGROUND: One of the most widely used methods to detect tuberculosis (TB) infection is the tuberculin skin test (TST). The completion of Mycobacterium tuberculosis (M. tuberculosis) genome sequence has led to identification of several antigens that can be utilized for accurate diagnosis and control of TB. The aim of this study was to purify the recombinant M. tuberculosis antigens for the evaluation of their potential in TB diagnosis. METHODS: The recombinant secretory antigens, ESAT-6, CFP-10 and ESAT-6/CFP-10 were produced by PCR and cloning methods. To investigate antigen specific responses of these recombinant antigens in detection of TB, ex vivo enzyme linked immunospot (ELISPOT) test in 30 clinically diagnosed TB patients was evaluated. RESULTS: The selected M. tuberculosis antigens were cloned, expressed and purified in Escherichia coli (BL21). ELISPOT assay for detection of TB showed the sensitivity of 93, 90 and 100% for recombinant ESAT-6, CFP-10 and ESAT-6/CFP-10 proteins respectively, which is significantly higher than conventional TST. CONCLUSION: The recombinant antigens of ESAT-6, CFP-10 and ESAT-6/CFP-10 can be used as an accurate means of detecting TB in Iran.