Antibodies against Mycobacterial Proteins as Biomarkers for HIV-Associated Smear-Negative Tuberculosis

Abstract

ABSTRACT Serology data are limited for patients with sputum smear-negative HIV-associated active tuberculosis (TB). We evaluated the serum antibody responses against the mycobacterial proteins MPT51, MS, and echA1 and the 38-kDa protein via enzyme-linked immunosorbent assay (ELISA) in South African (S.A.) HIV-positive (HIV + ) smear-negative TB patients ( n = 56), U.S. HIV + controls with a positive tuberculin skin test (TST + ; n = 21), and S.A. HIV-negative (HIV − ) ( n = 18) and HIV + ( n = 24) controls. TB patients had positive antibody reactivity against MPT51 (73%), echA1 (59%), MS (36%), and the 38-kDa protein (11%). Little reactivity against MPT51 and echA1 was observed in control groups at low risk for TB, i.e., S.A. HIV − (0% and 6%, respectively), and at moderate risk for TB development, i.e., U.S. HIV + TST + controls (14% and 10%, respectively). By contrast, more reactivity was detected in the S.A. HIV + control group at higher risk for TB (25% and 45%, respectively). Our data hold promise that antibody detection against MPT51 and echA1 might have adjunctive value in the detection of HIV + smear-negative TB and might reflect increasing Mycobacterium tuberculosis infection activity in asymptomatic HIV + individuals.