Enzyme-linked immunospot assay response to recombinant CFP-10/ESAT-6 fusion protein among patients with spinal tuberculosis: implications for diagnosis and monitoring of surgical therapy.

OBJECTIVE: This study aimed to assess the performance of a laboratory-developed recombinant CFP-10/ESAT-6 fusion protein (rCFP-10/ESAT-6)-based enzyme-linked immunospot (ELISPOT) assay for the diagnosis of spinal tuberculosis (TB) in China, and to evaluate the value of the ELISPOT assay for monitoring the efficacy of surgical treatment. METHODS: In the first part of the study, a total of 78 participants were consecutively recruited for ELISPOT using rCFP-10/ESAT-6 as a stimulus. The cutoff value for ELISPOT positivity was based on the results of receiver operating characteristic curve analysis. In the second part, this approach was evaluated in a prospective study including 102 patients with suspected spinal TB. Data on clinical characteristics of the patients and conventional laboratory results were collected, and blood samples were obtained for ELISPOT using rCFP-10/ESAT-6 as a stimulus. RESULTS: Among the 102 patients with suspected spinal TB, 11 were excluded from the study. Twenty-three patients (25.2%) had culture-confirmed TB and 29 (31.9%) patients had probable TB. Among the spinal TB patients, the ELISPOT had a sensitivity of 82.7%, compared to a sensitivity of 61.5% for the purified protein derivative (PPD) skin test. The specificity was 87.2% for ELISPOT and 46.2% for the PPD skin test among 39 subjects with non-TB disease. The number of spot-forming cells and/or the positive rate of the ELISPOT assay were associated with aging, emaciation, and paravertebral abscess. The number of subjects with responses to rCFP-10/ESAT-6 slightly decreased after surgical treatment in spinal TB patients. CONCLUSIONS: A laboratory-developed rCFP-10/ESAT-6 ELISPOT assay is a useful adjunct to current tests for the diagnosis of spinal TB.

Development and pre-clinical assessment of a 73 kD chimeric fusion protein as a defined sub-unit vaccine for leprosy.

Despite the advances toward the elimination of leprosy through widespread provision of multi-drug therapy to registered patients over the last 2 decades, new case detection rates have stabilized and leprosy remains endemic in a number of localized regions. A vaccine could overcome the inherent limitations of the drug treatment program by providing protection in individuals who are not already harboring the Mycobacterium leprae bacilli at the time of administration and effectively interrupt the transmission cycle over a wider timespan. In this report we present data validating the production of 73f, a chimeric fusion protein incorporating the M. leprae antigens ML2028, ML2346 and ML2044. The 73f protein was recognized by IgG in multibacillary (MB) leprosy patient sera and stimulated IFNγ production within whole blood assays of paucibacillary (PB) leprosy patient and healthy household contacts of MB patients (HHC). When formulated with a TLR4L-containing adjuvant (GLA-SE), 73f stimulated a strong and pluripotent Th1 response that inhibited M. leprae-induced inflammation in mice. We are using these data to develop new vaccine initiatives for the continued and long-term control of leprosy.

Prokaryotic expression, identification and bioinformatics analysis of fbpB-esxA fusing gene from Mycobacterium tuberculosis.

OBJECTIVE: To obtain fbpB-esxA fusing gene of Mycobacterium tuberculosis (MTB), express the encoded fusing protein in Escherichia coli (E. coli), identify protein acquired, and predict the structure and function of the protein utilizing methods of bioinformatics. METHODS: fbpB and esxA gene were amplified from genome of MTB H37Rv by PCR. The fbpB-esxA fusing gene ligated by (Gly(4)Ser)(3) linker was gained by means of Gene Splicing by Overlapping Extension PCR (SOE-PCR), and fusing gene was cloned into expression vector pET-30a. The recombinant plasmid was sequenced and expressed in E. coli BL21(DE3). The protein was identified by Western blot using anti-HIS antibody. Secondary structure and antigenic epitopes of the protein were predicting using tools of bioinformatics. RESULTS: The DNA sequences of fbpB-esxA were identical with that published by GenBank. The Ag85B-ESAT-6 fusion protein about 50 kDa comprised 485 amino acids was efficiently produced from expression system in E. coli BL21(DE3) under the induction of IPTG. Bioinformatics analysis showed the protein contained one transmembrane region and fourteen potential antigenic epitopes. CONCLUSIONS: The Ag85B-ESAT-6 fusion protein is successfully expressed with N-terminal HIS-tag. Gel filtration demonstrated that it exists as insoluble inclusion bodies mainly. The existence of linker doesn't affect immunogenicity of Ag85B and ESAT-6. It will allow for characterization in vitro and establish a foundation of further function research such as vaccine or diagnostic reagent.

Immunostimulatory activity of major membrane protein II from Mycobacterium tuberculosis.

Previously, we observed that both major membrane protein II of Mycobacterium leprae (MMP-ML) and its fusion with M. bovis BCG (BCG)-derived heat shock protein 70 (HSP70) (Fusion-ML) are immunogenic and that recombinant BCG secreting either of these proteins effectively inhibits the multiplication of M. leprae in mice. Here, we purified M. tuberculosis-derived major membrane protein II (MMP-MTB) and its fusion with HSP70 (Fusion-MTB) in a lipopolysaccharide-free condition and evaluated their immunostimulatory abilities. Both MMP-MTB and Fusion-MTB activated monocyte-derived dendritic cells (DC) in terms of phenotype and interleukin-12 (IL-12) production, but Fusion-MTB more efficiently activated them than MMP-MTB did. The IL-12 production was a consequence of the ligation of those recombinant proteins with Toll-like receptor 2. The M. tuberculosis-derived and M. leprae-derived recombinant proteins activated naïve T cells of both CD4 and CD8 subsets, but M. tuberculosis-derived proteins were superior to M. leprae-derived proteins and fusion proteins were superior to MMP, regardless of the origin of the protein. Memory-type CD4(+) T cells obtained from BCG-vaccinated healthy individuals seem to be primed with MMP-MTB by the vaccination, and both M. tuberculosis-derived recombinant proteins produced perforin-producing CD8(+) T cells from memory-type CD8(+) T cells. Further, infection of DC and macrophages with M. tuberculosis H37Ra and H37Rv induced the expression of MMP on their surface. These results indicate that M. tuberculosis-derived MMP, as a sole protein or as part of a fusion protein, may be useful for developing new vaccinating agents against tuberculosis.

Enhanced activation of T lymphocytes by urease-deficient recombinant bacillus Calmette-Guérin producing heat shock protein 70-major membrane protein-II fusion protein.

To activate naive T cells convincingly using Mycobacterium bovis bacillus Calmette-Guérin (BCG), recombinant BCG (BCG-D70M) that was deficient in urease, expressed with gene encoding the fusion of BCG-derived heat shock protein (HSP) 70 and Mycobacterium leprae-derived major membrane protein (MMP)-II, one of the immunodominant Ags of M. leprae, was newly constructed. BCG-D70M was more potent in activation of both CD4(+) and CD8(+) subsets of naive T cells than recombinant BCGs including urease-deficient BCG and BCG-70M secreting HSP70-MMP-II fusion protein. BCG-D70M efficiently activated dendritic cells (DCs) to induce cytokine production and phenotypic changes and activated CD4(+) T cells even when macrophages were used as APCs. The activation of both subsets of T cells was MHC and CD86 dependent. Pretreatment of DCs with chloroquine inhibited both surface expression of MMP-II on DCs and the activation of T cells by BCG-D70M-infected APCs. The naive CD8(+) T cell activation was inhibited by treatment of DCs with brefeldin A and lactacystin so that the T cell was activated by TAP- and proteosome-dependent cytosolic cross-priming pathway. From naive CD8(+) T cells, effector T cells producing perforin and memory T cells having migration markers were produced by BCG-D70M stimulation. BCG-D70M primary infection in C57BL/6 mice produced T cells responsive to in vitro secondary stimulation with MMP-II and HSP70 and more efficiently inhibited the multiplication of subsequently challenged M. leprae than vector control BCG. These results indicate that the triple combination of HSP70, MMP-II, and urease depletion may provide a useful tool for inducing better activation of naive T cells.

Rational design and evaluation of a multiepitope chimeric fusion protein with the potential for leprosy diagnosis.

Despite the reduction in the number of leprosy cases registered worldwide as a result of the widespread use of multidrug therapy, the number of new cases detected each year remains stable in many countries. This indicates that Mycobacterium leprae, the causative agent of leprosy, is still being transmitted and that, without an earlier diagnosis, transmission will continue and infection will remain a health problem. The current means of diagnosis of leprosy is based on the appearance of clinical symptoms, which in many cases occur after significant and irreversible nerve damage has occurred. Our recent work identified several recombinant antigens that are specifically recognized by leprosy patients. The goal of the present study was to produce and validate the reactivity of a chimeric fusion protein that possesses the antibody binding properties of several of these proteins. The availability of such a chimeric fusion protein will simplify future test development and reduce production costs. We first identified the antibody binding regions within our top five antigen candidates by performing enzyme-linked immunosorbent assays with overlapping peptides representing the amino acid sequences of each protein. Having identified these regions, we generated a fusion construct of these components (protein advances diagnostic of leprosy [PADL]) and demonstrated that the PADL protein retains the antibody reactivity of the component antigens. PADL was able to complement a protein that we previously produced (the leprosy IDRI [Infectious Disease Research Institute] diagnostic 1 [LID-1] protein) to permit the improved diagnosis of multibacillary leprosy and that had a good ability to discriminate patients with multibacillary leprosy from control individuals. A serological diagnostic test consisting of these antigens could be applied within leprosy control programs to reduce transmission and to limit the appearance of leprosy-associated disabilities and stigmatizing deformities by directing treatment.

Induction of cross-priming of naive CD8+ T lymphocytes by recombinant bacillus Calmette-Guerin that secretes heat shock protein 70-major membrane protein-II fusion protein.

Because Mycobacterium bovis bacillus Calmette-Guérin (BCG) unconvincingly activates human naive CD8(+) T cells, a rBCG (BCG-70M) that secretes a fusion protein comprising BCG-derived heat shock protein (HSP)70 and Mycobacterium leprae-derived major membrane protein (MMP)-II, one of the immunodominant Ags of M. leprae, was newly constructed to potentiate the ability of activating naive CD8(+) T cells through dendritic cells (DC). BCG-70M secreted HSP70-MMP-II fusion protein in vitro, which stimulated DC to produce IL-12p70 through TLR2. BCG-70M-infected DC activated not only memory and naive CD8(+) T cells, but also CD4(+) T cells of both types to produce IFN-gamma. The activation of these naive T cells by BCG-70M was dependent on the MHC and CD86 molecules on BCG-70M-infected DC, and was significantly inhibited by pretreatment of DC with chloroquine. Both brefeldin A and lactacystin significantly inhibited the activation of naive CD8(+) T cells by BCG-70M through DC. Thus, the CD8(+) T cell activation may be induced by cross-presentation of Ags through a TAP- and proteosome-dependent cytosolic pathway. When naive CD8(+) T cells were stimulated by BCG-70M-infected DC in the presence of naive CD4(+) T cells, CD62L(low)CD8(+) T cells and perforin-producing CD8(+) T cells were efficiently produced. MMP-II-reactive CD4(+) and CD8(+) memory T cells were efficiently produced in C57BL/6 mice by infection with BCG-70M. These results indicate that BCG-70M activated DC, CD4(+) T cells, and CD8(+) T cells, and the combination of HSP70 and MMP-II may be useful for inducing better T cell activation.

Use of protein antigens for early serological diagnosis of leprosy.

Leprosy is a chronic and debilitating human disease caused by infection with the Mycobacterium leprae bacillus. Despite the marked reduction in the number of registered worldwide leprosy cases as a result of the widespread use of multidrug therapy, the number of new cases detected each year remains relatively stable. This indicates that M. leprae is still being transmitted and that, without earlier diagnosis, M. leprae infection will continue to pose a health problem. Current diagnostic techniques, based on the appearance of clinical symptoms or of immunoglobulin M (IgM) antibodies that recognize the bacterial phenolic glycolipid I, are unable to reliably identify early-stage leprosy. In this study we examine the ability of IgG within leprosy patient sera to bind several M. leprae protein antigens. As expected, multibacillary leprosy patients provided stronger responses than paucibacillary leprosy patients. We demonstrate that the geographic locations of the patients can influence the antigens they recognize but that ML0405 and ML2331 are recognized by sera from diverse regions (the Philippines, coastal and central Brazil, and Japan). A fusion construct of these two proteins (designated leprosy IDRI diagnostic 1 [LID-1]) retained the diagnostic activity of the component antigens. Upon testing against a panel of prospective sera from individuals who developed leprosy, we determined that LID-1 was capable of diagnosing leprosy 6 to 8 months before the onset of clinical symptoms. A serological diagnostic test capable of identifying and allowing treatment of early-stage leprosy could reduce transmission, prevent functional disabilities and stigmatizing deformities, and facilitate leprosy eradication.

Enhancement of the sensitivity of the whole-blood gamma interferon assay for diagnosis of Mycobacterium bovis infections in cattle.

In this study, we determined if the sensitivity of the currently available in vitro test to detect bovine tuberculosis could be enhanced by adding the following immunomodulators: interleukin-2 (IL-2); granulocyte-macrophage colony-stimulating factor (GM-CSF); antibodies neutralizing IL-10 and transforming growth factor beta (TGF-beta); mono-methyl-l-arginine, which blocks nitric oxide production; and l-methyl-tryptophan, which interferes with the indoleamine dioxygenase pathway. Blood was obtained from uninfected control cattle, experimentally infected cattle, cattle responding positively to the skin test in tuberculosis-free areas (false positives), and cattle naturally infected with Mycobacterium bovis from New Zealand and Great Britain. Gamma interferon (IFN-gamma) responses to bovine purified protein derivative (PPD-b), avian purified protein derivative, and a fusion protein of ESAT-6 and CFP-10 were measured. Mono-methyl-l-arginine, l-methyl-tryptophan, or an antibody neutralizing TGF-beta had minimal impact on IFN-gamma production. IL-2 and GM-CSF promoted IFN-gamma release whether antigen was present or not. In contrast, adding an antibody against IL-10 enhanced only antigen-specific responses. In particular, addition of anti-IL-10 to ESAT-6/CFP-10-stimulated blood cultures enhanced the test sensitivity. Furthermore, whole blood cells from field reactors produced substantial amounts of IL-10 upon stimulation with PPD-b or ESAT-6/CFP-10. Testing "false-positive" cattle from tuberculosis-free areas of New Zealand revealed that addition of anti-IL-10 did not compromise the test specificity. Therefore, the use of ESAT-6/CFP-10 with anti-IL-10 could be useful to detect cattle potentially infected with tuberculosis, which are not detected using current procedures.

Activation of human CD4+ T cells by targeting MHC class II epitopes to endosomal compartments using human CD1 tail sequences.

Distinct CD4(+) T-cell epitopes within the same protein can be optimally processed and loaded into major histocompatibility complex (MHC) class II molecules in disparate endosomal compartments. The CD1 protein isoforms traffic to these same endosomal compartments as directed by unique cytoplasmic tail sequences, therefore we reasoned that antigen/CD1 chimeras containing the different CD1 cytoplasmic tail sequences could optimally target antigens to the MHC class II antigen presentation pathway. Evaluation of trafficking patterns revealed that all four human CD1-derived targeting sequences delivered antigen to the MHC class II antigen presentation pathway, to early/recycling, early/sorting and late endosomes/lysosomes. There was a preferential requirement for different CD1 targeting sequences for the optimal presentation of an MHC class II epitope in the following hierarchy: CD1b > CD1d = CD1c > > > CD1a or untargeted antigen. Therefore, the substitution of the CD1 ectodomain with heterologous proteins results in their traffic to distinct intracellular locations that intersect with MHC class II and this differential distribution leads to specific functional outcomes with respect to MHC class II antigen presentation. These findings may have implications in designing DNA vaccines, providing a greater variety of tools to generate T-cell responses against microbial pathogens or tumours.

Gamma interferon responses induced by a panel of recombinant and purified mycobacterial antigens in healthy, non-mycobacterium bovis BCG-vaccinated Malawian young adults.

We have previously shown that young adults living in a rural area of northern Malawi showed greater gamma interferon (IFN-gamma) responses to purified protein derivatives (PPD) prepared from environmental mycobacteria than to PPD from Mycobacterium tuberculosis. In order to define the mycobacterial species to which individuals living in a rural African population have been exposed and sensitized, we tested T-cell recognition of recombinant and purified antigens from M. tuberculosis (38 kDa, MPT64, and ESAT-6), M. bovis (MPB70), M. bovis BCG (Ag85), and M. leprae (65 kDa, 35 kDa, and 18 kDa) in >600 non-M. bovis BCG-vaccinated young adults in the Karonga District of northern Malawi. IFN-gamma was measured by enzyme-linked immunosorbent assay (ELISA) in day 6 supernatants of diluted whole-blood cultures. The recombinant M. leprae 35-kDa and 18-kDa and purified native M. bovis BCG Ag85 antigens induced the highest percentages of responders, though both leprosy and bovine tuberculosis are now rare in this population. The M. tuberculosis antigens ESAT-6 and MPT64 and the M. bovis antigen MPB70 induced the lowest percentages of responders. One of the subjects subsequently developed extrapulmonary tuberculosis; this individual had a 15-mm-diameter reaction to the Mantoux test and responded to M. tuberculosis PPD, Ag85, MPT64, and ESAT-6 but not to any of the leprosy antigens. We conclude that in this rural African population, exposure to M. tuberculosis or M. bovis is much less frequent than exposure to environmental mycobacteria such as M. avium, which have antigens homologous to the M. leprae 35-kDa and 18-kDa antigens. M. tuberculosis ESAT-6 showed the strongest association with the size of the Mantoux skin test induration, suggesting that among the three M. tuberculosis antigens tested it provided the best indication of exposure to, or infection with, M. tuberculosis.

Identification of an I-Ad restricted peptide on the 65-kilodalton heat shock protein of Mycobacterium avium.

The 65 kilodalton heat shock protein (Hsp65) from mycobacterial species elicits immune responses and in some cases protective immunity. Here we have used a DNA sublibrary approach to identify antigenic fragments of Mycobacterium avium Hsp65 and a synthetic peptide approach to delineate CD4+ T cell determinants. A panel of Hsp65 reactive CD4+ T cell clones was established from lymph node cells obtained from BALB/c mice immunized with recombinant Hsp65. The clones were tested for proliferative reactivity against the products of the DNA sublibrary of the hsp65 gene. A T cell epitope, restricted by the I-Ad molecule, was identified within the C-terminal region of Hsp65 and the minimal epitope (amino acid residues 489-503) delineated using overlapping peptides spanning the C-terminal fragment. Additionally, the CD4+ T cell clone recognizing this epitope also responded to native Hsp65 present in M. avium lysates by both proliferation and cytokine production, indicating that the epitope was present and processed similarly both in the native and the recombinant forms of Hsp65. This sequence identified in BALB/c mice (Hsp65 489-503) is identical in other mycobacteria, notably M. tuberculosis, M. bovis and M. leprae, suggesting the epitope may have wider application in murine models of other mycobacterial infections.

Antigenic specificity of the Mycobacterium leprae homologue of ESAT-6.

The sequence of the Mycobacterium leprae homologue of ESAT-6 shows only 36% amino acid correspondence to that from Mycobacterium tuberculosis. Anti-M. leprae ESAT-6 polyclonal and monoclonal antibodies and T-cell hybridomas reacted only with the homologous protein and allowed identification of the B- and T-cell epitopes. The protein is expressed in M. leprae and appears in the cell wall fraction. Thus, M. leprae ESAT-6 shows promise as a specific diagnostic agent for leprosy.

Ribosomal protein L7 included in tuberculin purified protein derivative (PPD) is a major heat-resistant protein inducing strong delayed-type hypersensitivity.

The tuberculin purified protein derivative (PPD) is a widely used diagnostic antigen for tuberculosis. It consists of more than 100 denatured proteins in a culture filtrate of a heated culture of Mycobacterium tuberculosis. In two-dimensional electrophoretic analysis of PPDs from M. tuberculosis and M. bovis BCG, most proteins were diffusely separated and could not be seen as spots because of denaturation, whereas a few proteins showed relatively clear spots, indicating heat resistance. Two such proteins corresponded to ribosomal proteins L7 and L12. The mixture of these proteins L7/L2 induced a strong delayed-type hypersensitivity reaction. Another protein showing a clear spot was a GroES analogue, but this did not induce delayed-type hypersensitivity. There were a few other unidentified proteins. It is well known that L7 and L12 are encoded by the same gene and that they differ from each other only by an acetylic post-translational modification that occurs at the N-terminus of L12 converting it to L7 in Escherichia coli. L12, but not L7, was found in two-dimensional electrophoresis of BCG ribosomes, although we found two proteins corresponding to L7 and L12 in PPDs and a native culture filtrate of BCG. We compared the delayed-type hypersensitivity reaction elicited by L7/L12 derived from a culture filtrate of BCG and L12 derived from BCG ribosomes. L7/L12 from the culture filtrate could induce delayed-type hypersensitivity, but L12 from ribosomes could not, indicating that L7 was attributable to the induction of delayed-type hypersensitivity. The activity of L7/L12 was heat resistant. Neither glycosylation nor phosphorylation of L7/L12 from a culture filtrate could be detected. The acetylation at N-terminal of L12 was essential for the delayed-type hypersensitivity activity.

Human T cell recognition of the Mycobacterium leprae LSR antigen: epitopes and HLA restriction.

We have in this work mapped epitopes and HLA molecules used in human T cell recognition of the Mycobacterium leprae LSR protein antigen. HLA typed healthy subjects immunized with heat killed M. leprae were used as donors to establish antigen reactive CD4+ T cell lines which were screened for proliferative responses against overlapping synthetic peptides covering the C-terminal part of the antigen sequence. By using this approach we were able to identify two epitope regions represented by peptide 2 (aa 29-40) and peptide 6 (aa 49-60), of which the former was mapped in detail by defining the N- and C-terminal amino acid positions necessary for T cell recognition of the core epitope. MHC restriction analysis showed that peptide 2 was presented to T cells by allogeneic cells coexpressing HLA-DR4 and DRw53 or DR7 and DRw53. In contrast, peptide 6 was presented to T cells only in the context of HLA-DR5 molecules. In conclusion, the M. leprae LSR protein antigen can be recognized by human T cells in the context of multiple HLA-DR molecules, of which none are reported to be associated with the susceptibility to develop leprosy. The results obtained are in support of using the LSR antigen in subunit vaccine design.

Mapping of a protective epitope of the CopB outer membrane protein of Moraxella catarrhalis.

A monoclonal antibody (MAb) (MAb 10F3) directed against the CopB outer membrane protein of Moraxella catarrhalis previously was found to enhance pulmonary clearance of M. catarrhalis in an animal model (M. Helminen, I. Maciver, J. L. Latimer, L. D. Cope, G. H. McCracken, Jr., and E. J. Hansen, Infect. Immun. 61:2003-2010, 1993). In the present study, this same MAb was shown to exert complement-dependent bactericidal activity against this pathogen in vitro. Nucleotide sequence analysis of the copB gene from two MAb 10F3-reactive and two MAb 10F3-unreactive strains of M. catarrhalis revealed that the deduced amino acid sequences of these four CopB proteins were at least 90% identical. Comparison of the amino acid sequences of these proteins allowed localization of possible MAb 10F3 binding sites to five relatively small regions of the CopB protein from M. catarrhalis O35E. When five synthetic peptides representing these regions were tested for their ability to bind MAb 10F3 in a direct enzyme-linked immunosorbent assay system, an oligopeptide containing 26 amino acids was shown to bind this MAb. The actual binding region for MAb 10F3 was localized further through the use of overlapping decapeptides that spanned this 26-mer. A fusion protein containing the same 26-mer readily bound MAb 10F3 and was used to immunize mice. The resultant antiserum contained antibodies that reacted with the CopB protein of the homologous M. catarrhalis strain in Western blot analysis and bound to the surface of both homologous and heterologous strains of M. catarrhalis.

Analysis of T-cell and B-cell responses to recombinant M. leprae antigens in leprosy patients and in healthy contacts: significant T-cell responses to antigens in M. leprae nonresponders.

The recognition of a panel of recombinant Mycobacterium leprae antigens by T cells and B cells from 29 borderline tuberculoid/tuberculoid (BT/TT) and 18 lepromatous leprosy (LL) patients and from 21 healthy controls (HC) in leprosy-endemic regions of Ethiopia was examined. All 11 antigenic molecules tested (including M. leprae hsp 10, hsp18, hsp65 and several novel M. leprae antigens) were shown to be recognized by T cells, but clear quantitative differences existed between reactivities induced by individual antigens. Similar quantitative differences were observed when antibody responses to hsp10 and hsp65 antigens were determined. No associations were found between the antigen-specific responses and the subject status of either BT/TT and LL patients or HC. Fifteen percent of the patients who were nonresponsive to sonicates of M. leprae showed significant T-cell responses to one or more individual M. leprae antigens. This indicates that M. leprae constituents other than the proteins tested are responsible for the M. leprae-specific nonresponsiveness in these patients, which may be exploited for the design of vaccines or immunotherapeutic modalities aimed at inducing M. leprae-specific immunity in nonresponders.

A 46 kDa integral membrane protein from Mycobacterium leprae resembles a number of bacterial and mammalian membrane transport proteins.

In this paper we describe the nucleotide sequence of a 3.4 kbp region of the Mycobacterium leprae genome. This region contains an open reading frame of 1290 bp with a coding capacity for a protein of 46,179 Da, designated the 38L protein. Using antibodies against part of the 38L protein, we were able to demonstrate that the 38L protein is present in the membrane protein fraction of M. leprae. The 38L protein showed significant matches with a number of integral membrane proteins involved in the transport of small molecules through the cellular membrane. Among these are a human and a murine protein involved in melanin biosynthesis. The 38L protein might play a role in the hypopigmentation observed in leprosy patients.