EVALUATION OF A WESTERN-BLOT SERUM TEST FOR THE DIAGNOSIS OF MYCOBACTERIUM-TUBERCULOSIS INFECTION

This study was designed to evaluate the possibility of monitoring Myco bacterium tuberculosis infection using a serological assay. A discrimi nant score comprising antigen fractions of 38, 28, 24 and 19 kDa, iden tified in western blots using the Mycobacterium bovis bacille Calmette -Guerin (BCG) A60 antigen complex was established in a sample of 57 pu rified protein derivative (PPD)-negative and 47 PPD-positive individua ls. It was then tested in a group of 140 subjects undergoing BCG vacci nation as a model of tuberculosis complex infection and in a group of human immunodeficiency virus (HIV)-infected individuals as a model of cell-mediated immunodeficiency-related risk of tuberculosis. The discr iminant score identified 57 out of 57 (100%) PPD-positives and none (0 %) of the 47 PPD-negatives. In the BCG vaccinated subjects, 1.4% teste d positive before vaccination and 90% after vaccination In the HIV-pos itive subjects, 90% of the PPD-positive and 5% of the PPD-negative sub jects had a positive score. This study suggests that the western blot discriminant score is an accurate test to survey M. tuberculosis infec tion in serum samples.