Use of Low Molecular Weight Antigens of Mycobacterium tuberculosis as a New Skin Test for Specific Diagnosis of Tuberculosis

Tuberculosis (TB) is an infectious disease and about one-third of the world population are infected with latent TB infection. Active TB infection may develop in 5 to10 percent of individuals with latent infection; therefore, detection of latent infection is of great importance in the control of the disease. The aim of this study was to develop a specific skin test based on low molecular weight proteins secreted by M. tuberculosis for detection of M. tuberculosis infection.
At this study, after extraction of secreted proteins from short-term culture filtrate of M. tuberculosis, low molecular weight proteins, were purified by Sephadex-G75 gel chromatography. For skin test, several groups of guinea pigs were sensitized with M. tuberculosis, M. bovis BCG, and M. avium strains, and then skin test were performed using purified proteins and PPD.
According to skin test data, unlike PPD, purified proteins showed a positive response in animals exposed to M. tuberculosis, but no significant skin responses was observed in the guinea pigs sensitized with M. bovis BCG and M. avium strains.
The results of this study demonstrated that new skin test is specific compared to PPD in the detection of M. tuberculosis infection, and could be replaced as a more specific skin test for detection of TB in large animals or human.