Evaluation of Mycobacterium tuberculosis Early Secreted Antigenic Target 6 Recombinant Protein as a Diagnostic Marker in Skin Test.
OBJECTIVE
Tuberculosis (TB) is the leading infectious disease in the developing world. Delayed-type hypersensitivity skin test diagnoses TB using tuberculin purified protein derivative (PPD), but this test is incapable of distinguishing Mycobacterium tuberculosis (MTB) infection from bacillus Calmette-Guérin (BCG) vaccination or an infection caused by nontuberculous mycobacteria (NTM). This study was performed to evaluate the use of recombinant early secretory antigenic target 6 (rESAT-6), a secretory protein found only in MTB, Mycobacterium bovis, and few other mycobacterial species, as a skin marker for MTB in guinea pigs.


METHODS
We prepared recombinant MTB ESAT-6 and evaluated its use as a specific antigen for MTB in guinea pigs.


RESULTS
Our results show that the purified MTB rESAT-6 antigen is capable of inducing a positive reaction only in guinea pigs sensitized to MTB. No such reaction was observed in the animals sensitized to M. bovis, BCG vaccination, or NTM (Mycobacterium avium).


CONCLUSIONS
Our study results confirm that the ESAT-6 antigen is more specific to MTB infection than PPD and could be used in more specific skin tests for detection of MTB in large animals and in humans.
Department of TB, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Jale
J
Moradi
Department of TB, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Nader
N
Mosavari
Department of TB, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Mahmoud
M
Ebrahimi
Department of TB, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Reza
R
Arefpajohi
Department of TB, Razi Vaccine and Serum Research Institute, Karaj, Iran.
Majid
M
Tebianian
Mycobacterium tuberculosis; early secretory antigenic target 6; pQE60 vector; purified protein derivative; recombinant early secretory antigenic target 6