[BCG vaccination to Mycobacterium leprae infection in mice].

BCG vaccine (Tokyo strain) was given in BALB/cA mice intradermally 1 or 3 months before Mycobacterium leprae (M. leprae) challenge as modified Shepard's method. The vaccine dosage was 10(7-8) or 10(6). The BCG gave good protection in both dosages and both challenges against M. leprae infection. Lymphocytes proliferations of BCG-vaccinated splenocyte cultures in response to M. leprae lysate or BCG components (hsp65, 38 kD, 30 kD or 12 kD protein) were tested, and potent proliferative responses were seen in the cultures with M. leprae lysate and hsp65. Furthermore, gamma-IFN productions were positive in the cultures with M. leprae lysate or hsp65, but negative with other antigens. The production of gamma-IFN with hsp65 was never inhibited with polymyxin B, but inhibited with IL-10. These results show that BCG (Tokyo strain) is a useful vaccine for M. leprae infection in mice, and one of the components of BCG, hsp65, may be a effective antigen component for protection of M. leprae infection inducing Th1 type cytokine.

Identification and functional characterization of thioredoxin of Mycobacterium tuberculosis.

We have previously described a Mycobacterium tuberculosis protein designated MPT46 that was present in culture filtrates. Here we report that the MPT46 protein is thioredoxin of M. tuberculosis. MPT46 is recognized by antibodies to thioredoxin (Trx) of Escherichia coli, and antibodies of MPT46 recognize Mycobacterium leprae Trx. Moreover, MPT46 was shown to have enzymatic activity identical to that of Trx of other species, such as its ability to reduce insulin. These findings identify MPT46 as a functionally active Trx.

Identification of an antigenic domain on Mycobacterium leprae protein antigen 85B, which is specifically recognized by antibodies from patients with leprosy.

Sixty-three overlapping 15-oligomer peptides covering the 30-kDa protein antigen 85B of Mycobacterium leprae were tested by ELISA to identify epitopes recognized by human antibodies. Serum samples from patients with lepromatous leprosy (LL) reacted mainly with peptides comprising amino acid regions (AA) 206-230, 251-280, and 291-325. Sera of patients with active tuberculosis who responded to the native 30-kDa antigen did not recognize these peptides. The antibody-binding specificity to the defined B cell regions was evaluated in a blind study with 71 serum samples from patients and household contacts living in Ethiopia where leprosy is endemic. The peptide of AA 256-280 was recognized by 88% of LL patients, 15% of patients with tuberculoid leprosy, and none of the contacts. These findings suggest that there are major linear B cell epitopes on the M. leprae 30-kDa protein that are recognized by lepromin-negative LL patients, whereas lepromin-positive patients respond preferentially to conformational epitopes.

Quantitative and qualitative studies on the major extracellular antigen of Mycobacterium tuberculosis H37Rv and Mycobacterium bovis BCG.

The Mycobacterium tuberculosis antigen 85 is a biologically important antigen. Tuberculosis patients may have strong antibodies against it, and their peripheral blood mononuclear cells respond to it with gamma-interferon production and lymphocyte proliferation. Antigen 85 is actively secreted into the culture medium during culture in vitro and is known to bind human fibronectin. A double-antibody enzyme-linked immunosorbent assay (ELISA) for quantification of antigen 85 is described. A mouse monoclonal antibody, HYT27, was used as capture antibody in the assay. HYT27 was characterized in crossed immunoelectrophoresis and found to bind all three components of the antigen 85 complex. By radioimmunoassay, HYT27 was found to bind equally well to antigens 85A and 85B. In the ELISA assay, a rabbit anti-antigen 85 antiserum was used in the second antibody layer. The specificity of the assay was tested using several different antigen preparations. The purified BCG 85A and 85B components were compared, and there was a 10 times lower sensitivity for antigen 85A due to weaker rabbit antibodies toward this component. The purified components MPT44 and MPT59 from M. tuberculosis H37Rv were compared with the components of BCG and found to correspond to BCG 85A and 85B, respectively. Mycobacterium kansasii and Mycobacterium avium both contained partially identical antigens. Small amounts of antigen 85 were detected in Mycobacterium leprae sonicates. Detecting antigen 85 by sensitive methods may be of great value in the early diagnosis of mycobacterial disease.

MPB59, a widely cross-reacting protein of Mycobacterium bovis BCG.

The MPB59 protein of Mycobacterium bovis BCG was purified to homogeneity from culture fluid of BCG substrain Tokyo, and characterized by biochemical and immunological techniques. The molecular weight was 28,000, determined by SDS-polyacrylamide gel electrophoresis, and the pI value was 5.3. The N-terminal amino acid sequence was determined for 32 steps and showed no significant homology with MPB64, MPB70 or MPB80. By crossed immunoelectrophoresis, MPB59 was found to belong to the BCG antigen 85 complex and identified as corresponding to the 85B component of this complex. The protein cross-reacted extensively with other species of mycobacteria, and induced a marked humoral immune response in armadillos and monkeys during development of systemic mycobacterial infection after inoculation with Mycobacterium leprae.