Diagnosis of Tuberculosis by Using ELISA to Detect 38 kDa Mycobacterial Antigen in The Patients

Tuberculosis (TB), caused mainly by Mycobacterium tuberculosis, is a major health problem. It has been found in Neolithic remains, and is still the largest cause of death from a single infectious disease. There are about 20 million new active cases of TB each year and there are between 3-8 million deaths per year from this infection. This represents greater than 25% of all avoidable deaths worldwide.
The importance of mycobacterial secreted proteins in infection has been suggested by many investigators. Three important antigens, the 38 kDa, 30/31 kDa and SOD molecules, have been found to be secreted by M. tuberculosis. The importance of the 38 kDa in TB has been shown by many investigators. We have developed different tests for the detection of these antigens in the TB patients sera. The performance of both a Direct and Sandwich ELISA using FF11 (anti-38 kDa m-Ab) for the detection of the 38 kDa M. tuberculosis antigen has been evaluated in our study.
This test been found to have a specificity of 84-88% with positive predictive values of 80 84% which, although not ideal, is quite helpful in developing some new specific diagnostic test. Our test has the advantage that antigens may be detected in the early stages of infection and we have shown that it can be used for monitoring effective chemotherapy by detecting the decline in the 38 kDa antigen in previously positive patients. However, a detailed study is needed on larger numbers of confirmed TB cases and normals.