Abstract

An accurate laboratory diagnosis is essential for the effective management of pulmonary tuberculosis patients. This study is precisely aimed at developing an immunodiagnostic assay, using recombinant mycobacterial antigens for the accurate laboratory diagnosis of pulmonary tuberculosis. An indirect ELISA was standardized to measure serum IgG antibody levels against four recombinant mycobacterial antigens (ESAT-6, PlcA, HspX and Tb8.4) in sputum culture-negative, smear negative patients with pulmonary tuberculosis. The sensitivity of the ELISA with PlcA, HspX, Tb8.4 and ESAT-6 were 41.7, 63.3, 45 and 53.3% respectively. A higher sensitivity (76.7%) in ELISA could be achieved when a multiantigen cocktail, consisting of all the above four antigens, was used. These antigens did not give false positive results in the sera of healthy control subjects. The specificity of PlcA, HspX, Tb8.4, ESAT-6 and multiantigen cocktail in ‘disease controls’ were 95.7, 93.5, 94.6, 93.5 and 94.6%. High specificity and sensitivity of ELISA with these recombinant mycobacterial antigens in cocktail indicates that they can be used for the diagnosis of pulmonary tuberculosis particularly in patients.

Key words: Mycobacterium tuberculosis, recombinant mycobacterial antigens, serology, tuberculosis