The identification and characterization of antigens of Mycobacterium tuberculosis help in understanding the mechanisms of protective immunity and in improving diagnostic methods for TB. Rv0057 and Rv1352 proteins are new T-cell antigens, found to play roles in TB infection. In this study, a recombinant fusion protein Rv0057-Rv1352 was made and analyzed for its immunological characteristics and potential utility. It showed good immunoreactivity with serum from TB patients by western blotting. The antibody levels against Rv0057-Rv1352 were significantly higher in sera from 69 TB patients than in sera from 60 patients with non-TB respiratory diseases (P<0.001). The sensitivities of a diagnostic ELISA test based on detecting Rv0057-Rv1352 antibody (60.3%) or 38 kDa-16 kDa antibody (58.8%) were comparable to commercial rapid test B (75.4%), and significantly higher (p<0.001) than bacteriological methods (15.9%), rapid test A (20.3%), or rapid test C (29.0%). The specificities of Rv0057-Rv1352 (93.3%) or 38 kDa-16 kDa antibody tests (93.3%) were equivalent to the rapid tests A (93.3%) and C (86.7%), and significantly higher than rapid test B (63.3%, p<0.001). When 38 kDa-16 kDa was used together with Rv0057-Rv1352, the test sensitivity reached 85.5%, and its specificity remained high (86.7%). The test was as sensitive with bacterium-positive TB patients as with bacterium-negative. In an ELISPOT assay for cellular immunity, Rv0057-Rv1352 stimulated T lymphocytes to produce fewer spots secreting IFN-γ than CFP10-ESAT6 fusion protein did (p>0.05). These results suggest that Rv0057-Rv1352 has potential for the serodiagnosis of active pulmonary TB.
Keywords: Antigenicity; Mycobacterium tuberculosis; Recombinant fusion protein; Rv0057; Rv1352; serodiagnosis.
© 2015 by the Association of Clinical Scientists, Inc.