Candidate antigens for improved serodiagnosis of tuberculosis

Abstract

Objective: To explore the possibility that an analysis of antibody specificity to separated components of mycobacteria in a group of tuberculous patients may reveal a combination of target antigens whose antibodies could form the basis of a useful serodiagnostic test. Design: Immunoblots of 1-dimensional (SDS-PAGE) and 2-dimensional (isoelectric focusing/SDS-PAGE) separation of antigenic extracts of Mycobacterium tuberculosis H37Rv (MTSE) and M. bovis bacille CalmetteGuérin (BCG) (MBSE) with 52 tuberculous and 59 BCG-vaccinated control human sera were analyzed for band and spot reactivity patterns that are indicative of infection with M. tuberculosis. Results: Reactivity to antigens banding in the 10–18 kDa, 37–43 kDa and 70–90 kDa regions allowed a good discrimination between patients and normal subjects. Patients' sera reacting with antigens in the 22–30 and 70–88 kDa regions differentiated responses to MTSE and MBSE. In 2-D immunoblotting, patients' sera only reacted with antigens separating at ∼ pI 6.5 26–28 kDa, pI 4.8 38 kDa and pI 6.5 70–79 kDa position and the responses were specific for M. tuberculosis (MTSE). Conclusion: These results provide evidence that a combination of these M. tuberculosis antigens may be a useful basis for developing a diagnostic antibody test. Additionally, they may help to define antigens, and host antibody responses that are specific to one but not the other of the two closely related species.