Assessment of an ELISA for serodiagnosis of active pulmonary tuberculosis in a Cuban population

Abstract Objective To explore the serodiagnostic potential of the five recombinant Mycobacterium tuberculosis antigens CFP-10 (Rv3874), ESAT-6 (Rv3875), APA (Rv1860), PstS-1 (Rv0934), Ag85A (Rv3804c) and their combination in a Cuban population with active pulmonary tuberculosis. Methods The serodiagnostic potential of the recombinant antigens rESAT-6, rCFP-10, rAPA, rPstS-1 produced in Escherichia coli , rAg85A produced in Streptomyces lividans and the combination of the five proteins was evaluated by an indirect ELISA. Humoral immune response was analysed in a group of 140 patients with active pulmonary tuberculosis (smear-, Mantoux- and culture-positive) and in a control group consisting of 34 bacillus Calmette-Guerin vaccinated, Mantoux-negative, healthy subjects. Results With the exception of CFP-10, the use of the separate recombinant antigens or the antigenic cocktail in ELISA-based serodiagnosis resulted in a significant difference in the mean optical densitiy values between sera of patients and healthy subjects. The highest sensitivity of the assay using single antigens, being 58.57%, was achieved with rPstS-1 compared to 27.14% with rCFP-10, 31.65% with Ag85A, 42.86% with rAPA and 44.29% with rESAT-6. Single antigen ELISAs provided high specificity values ranging from 94.12% to 97.06%. A cocktail of the aforementioned antigens increased the sensitivity to 87.14% and the specificity to 97.06%. Conclusions An ELISA using a multi-antigen mix containing recombinant immuno-dominant antigens of Mycobacterium tuberculosis , namely, rCFP-10, rESAT-6, rAPA, rPstS-1 and rAg85, increases the sensitivity and specificity compared with that using the single antigens and shows potential as a complementary tool for the diagnosis of active pulmonary tuberculosis in Cuba.