Enhanced serodiagnostic utility of novel Mycobacterium tuberculosis polyproteins

The detection of Mycobacterium tuberculosis specific antibodies in human sera has been a rapid and important diagnostic aid for tuberculosis (TB) control and prevention. However, any single antigen is not enough to be used to cover the antibody profiles of all TB patients.

Seven single antigens (38 kDa, ESAT-6, CFP10, Mtb8.4, MPT64, TB16.3 and Mtb8) were evaluated serodiagnostically. Two novel M. tuberculosis polyproteins, 38kD-ESAT6-CFP10 (38F) and Mtb8.4-MPT64-TB16.3-Mtb8 (64F), were expressed and the novel 38F-64F indirect ELISA assay used to analyze antibody responses to polyproteins in serum samples.

The sensitivity of the novel 38F-64F indirect ELISA alone was much higher than that of the sputum culture test (86.91% vs. 50.62%) and that of the sputum smear test (78.64% vs. 47.57%). The novel 38F-64F indirect ELISA had a sensitivity of 74.16% with sera from extrapulmonary TB patients and a sensitivity of 37.14% with sera from LTBI. The specificity of the novel 38F-64F indirect ELISA was 90.36% with the sera from healthy blood donors and 94.15% with the sera from non-TB patients.

The novel 38F-64F indirect ELISA assay had effective diagnostic performance and would make meaningful contribution to the diagnosis of TB disease in developing countries.