Improved diagnosis of tuberculosis in HIV-positive patients using RD1-encoded antigen CFP-10.

Rao, P.V.; Kumar, M.K.; Basirudeen, S.; Sharma, P.; Swaminathan, S.; Raja, A.

International Journal of Infectious Diseases; 2009; 13; 613—622.

Summary: Objective: The present study was aimed at determining the serodiagnostic potential of 38-kDa (Rv0934, Mycobacterium tuberculosis complex-specific antigen) and CFP-10 (Rv3874, RD1 antigen) antigens among HIV-positive and HIV-negative patients with pulmonary TB.

Methods: The diagnostic potential of native 38-kDa (n38-kDa) and recombinant CFP-10 (rCFP-10) antigens was ascertained in terms of sensitivity and specificity using an indirect ELISA. The study included 508 HIV-seronegative TB patients (TB), 54 HIV-seropositive TB patients (HIV—TB), 30 HIV positive patients without TB (HIV), and 256 controls.

Results: In HIV—TB, the sensitivities for individual antigens ranged from 14.8% to 31.5% and the specificity was >98% for IgG. When IgA results were added to IgG, the sensitivity increased to 25.9% for 38-kDa and 57.4% for CFP-10; specificity changed to 97.5% for 38-kDa and 98.1% for CFP-10. The combined results of both the antigens gave 59.3% sensitivity and 95.6% specificity. In TB, the sensitivity was 82.8% when the antigen results were combined. None of the HIV-infected controls showed positivity for IgG to either of the two antigens.

Conclusion: Use of CFP-10 enhances the sensitivity of 38-kDa, and therefore the 38-kDa and CFP-10 antigen combination can be a diagnostic marker in HIV—TB.

Keywords: RD1; Serodiagnosis; CFP-10; Tuberculosis; HIV—TB; ELISA

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