A Postgenomic Approach to Identification of<i>Mycobacterium leprae</i>-Specific Peptides as T-Cell Reagents

Dockrell, Hazel M.; Brahmbhatt, S.; Robertson, Brian D.; Britton, Sven; Fruth, Uli; Gebre, Negussie; Hunegnaw, Mesfin; Hussain, Rabia; Manandhar, Rakesh; Murillo, Luis A.; Pessolani, Maria Cristina Vidal; Roche, Paul; Salgado, Jorge; Sampaio, Elizabeth P.; Shahid, Firdaus; Thole, Jelle; Young, Douglas

doi:10.1128/iai.68.10.5846-5855.2000

Cited by 41 publications

(24 citation statements)

References 25 publications

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“…In the present study, instead of abandoning the nonspecific molecules as diagnostic reagents, we dissected the proteins by testing overlapping peptides spanning their sequence and divided them into specific and nonspecific moieties. A peptide-based diagnostic approach has also been attempted for leprosy, but although high specificity was demonstrated, the selected specific peptides gave a relatively low sensitivity (14). We made the same observation in the present study; selecting only the regions of the protein without cross-reactive epitopes decreased the sensitivity.…”

Section: Discussionsupporting

confidence: 70%

Specific T-Cell Epitopes for Immunoassay-Based Diagnosis ofMycobacterium tuberculosisInfection

et al. 2004

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The currently used method for immunological detection of tuberculosis infection, the tuberculin skin test, has low specificity. Antigens specific for Mycobacterium tuberculosis to replace purified protein derivative are therefore urgently needed. We have performed a rigorous assessment of the diagnostic potential of four recently identified antigens (Rv2653, Rv2654, Rv3873, and Rv3878) from genomic regions that are lacking from the Mycobacterium bovis bacillus Calmette-Guérin (BCG) vaccine strains as well as from the most common nontuberculous mycobacteria. The fine specificity of potential epitopes in these molecules was evaluated by sensitive testing of the T-cell responses of peripheral blood mononuclear cells derived from M. bovis BCGvaccinated healthy individuals to synthesized overlapping peptides. Three of the four molecules contained regions with significant specificity problems (Rv2653, Rv3873, and Rv3878). We selected and combined the specific peptide stretches from the four proteins not recognized by M. bovis BCG-vaccinated individuals. These peptide stretches were tested with peripheral blood mononuclear cells obtained from patients with microscopyor culture-confirmed tuberculosis and from healthy M. bovis BCG-vaccinated controls. The combination of the most promising stretches from this analysis showed a sensitivity level (57%) comparable to the level found with the two well-known M. tuberculosis-specific proteins ESAT-6 and CFP-10 (75 and 66%, respectively). The combination of ESAT-6, CFP-10, and the novel specific peptide stretches gave an overall sensitivity of 84% at a specificity of 97%. In a validation experiment with new experimental groups, the sensitivities obtained were 57% for the combination of peptides and 90% for the combination of the peptides, ESAT-6, and CFP-10. This combination gave a specificity of 95%.Tuberculosis is a major cause of morbidity and mortality throughout the world. It is estimated that nearly 1% of the world population is newly infected each year and that approximately one-third of the world population is latently infected with Mycobacterium tuberculosis.On average, immunocompetent individuals infected with M. tuberculosis have a lifetime risk of developing active tuberculosis of 10%, but this risk increases to a 10% yearly risk in persons coinfected with human immunodeficiency virus. If left untreated, a patient with active pulmonary tuberculosis will transmit the infection to 10 to 15 contacts each year (World Health Organization, tuberculosis fact sheet no. 104, http: //www.who.int/mediacentre/factsheets/who104/en/, 2000). Therefore, novel tools to detect and subsequently treat infected individuals before the disease progresses to active contagious tuberculosis are an international research priority (10).In addition to chest radiographs to detect pulmonary tuberculosis, the current diagnostic assays for the detection of infection with M. tuberculosis include culture, microscopy and PCR of relevant patient material, and the tuberculin skin test. The first three me...

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Section: Discussionsupporting

confidence: 70%

Specific T-Cell Epitopes for Immunoassay-Based Diagnosis ofMycobacterium tuberculosisInfection

et al. 2004

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“…Scrutiny of the M. leprae genome revealed the presence of two candidate genes, ML0049 and ML0050, that encode the M. leprae homologs of ESAT-6 and CFP-10, respectively (16,17,21,22). We recently reported that recombinant M. leprae ESAT-6 and CFP-10 proteins were efficiently recognized by T cells from the majority of M. leprae responsive leprosy patients (12,16). Despite limited sequence identity with their M. tuberculosis homologues Rv3875 and Rv3874 (36 and 40%, respectively), however, significant immunologic cross-reactivity with M. tuberculosis proteins was found for human T cells.…”

Section: Discussionmentioning

confidence: 99%

“…Prior to the completion of the M. leprae genome sequence, the search for M. leprae-specific antigens that stimulate cellular rather than humoral immunity led to the identification of several antigens and peptides that were able to induce T-cell responses in vitro (12,16,17). Unfortunately, for most of these antigens, homologues were later found in other mycobacteria, including M. tuberculosis, which limits the diagnostic potential of these antigens for leprosy (6,21,22).…”

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confidence: 99%

Postgenomic Approach To Identify Novel Mycobacterium leprae Antigens with Potential To Improve Immunodiagnosis of Infection

et al. 2005

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Early detection of Mycobacterium leprae infection is considered an important component of strategies aiming at reducing transmission of infection, but currently available diagnostic tools often lack sufficient sensitivity and specificity to reach this goal. Recent comparative genomics have revealed the presence of 165 M. leprae genes with no homologue in M. tuberculosis. We selected 17 of these genes for further study. All 17 genes were found to be expressed at the mRNA level in M. leprae from infected mice and from a multibacillary leprosy patient. Additional comparative genomic analyses of all currently available mycobacterial genome databases confirmed 12 candidate genes to be unique to M. leprae, whereas 5 genes had homologues in mycobacteria other than M. tuberculosis. Evaluation of the immunogenicity of all 17 recombinant proteins in PBMC from 127 Brazilians showed that five antigens (ML0576, ML1989, ML1990, ML2283, and ML2567) induced significant gamma interferon levels in paucibacillary leprosy patients, reactional leprosy patients, and exposed healthy controls but not in most multibacillary leprosy patients, tuberculosis patients, or endemic controls. Importantly, among exposed healthy controls 71% had no detectable immunoglobulin M antibodies to the M. leprae-specific PGL-I but responded to one or more M. leprae antigen(s). Collectively, the M. leprae proteins identified are expressed at the transcriptome level and can efficiently activate T cells of M. leprae-exposed individuals. These proteins may provide new tools to develop tests for specific diagnosis of M. leprae infection and may enhance our understanding of leprosy and its transmission.

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“…A previous study using M. leprae-derived peptides showed considerable variation in peptide reactivity at different sites (8). Thus, in order to estimate the potential of the peptides for detecting M. lepraespecific T-cell immunity in the context of genetically different backgrounds, we selected the most promising peptides (n ϭ 22) and proteins (n ϭ 5) from the previous studies in Brazil, four other countries of leprosy endemicity in Asia (Nepal, Bangladesh, and Pakistan) and Africa (Ethiopia), and an additional site in west central Brazil (Goiás State).…”

Section: The Detection Of Hundreds Of Thousands Of New Cases Of Lepromentioning

confidence: 99%

From Genome-Based In Silico Predictions to Ex Vivo Verification of Leprosy Diagnosis

Geluk

Spencer

Bobosha

et al. 2009

Clin Vaccine Immunol

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The detection of hundreds of thousands of new cases of leprosy every year suggests that transmission of Mycobacterium leprae infection still continues. Unfortunately, tools for identification of asymptomatic disease and/or early-stage M. leprae infection (likely sources of transmission) are lacking. The recent identification of M. leprae-unique genes has allowed the analysis of human T-cell responses to novel M. leprae antigens. Antigens with the most-promising diagnostic potential were tested for their ability to induce cytokine secretion by using peripheral blood mononuclear cells from leprosy patients and controls in five different areas where leprosy is endemic; 246 individuals from Brazil, Nepal, Bangladesh, Pakistan, and Ethiopia were analyzed for gamma interferon responses to five recombinant proteins (ML1989, ML1990, ML2283, ML2346, and ML2567) and 22 synthetic peptides. Of these, the M. leprae-unique protein ML1989 was the most frequently recognized and ML2283 the most specific for M. leprae infection/exposure, as only a limited number of tuberculosis patients responded to this antigen. However, all proteins were recognized by a significant number of controls in areas of endemicity. T-cell responses correlated with in vitro response to M. leprae, suggesting that healthy controls in areas where leprosy is endemic are exposed to M. leprae. Importantly, 50% of the healthy household contacts and 59% of the controls in areas of endemicity had no detectable immunoglobulin M antibodies to M. leprae-specific PGL-I but responded in T-cell assays to >1 M. leprae protein. T-cell responses specific for leprosy patients and healthy household contacts were observed for ML2283-and ML0126-derived peptides, indicating that M. leprae peptides hold potential as diagnostic tools. Future work should concentrate on the development of a sensitive and field-friendly assay and identification of additional peptides and proteins that can induce M. leprae-specific T-cell responses.

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A Postgenomic Approach to Identification ofMycobacterium leprae-Specific Peptides as T-Cell Reagents

Cited by 41 publications

References 25 publications

Specific T-Cell Epitopes for Immunoassay-Based Diagnosis ofMycobacterium tuberculosisInfection

Specific T-Cell Epitopes for Immunoassay-Based Diagnosis ofMycobacterium tuberculosisInfection

Postgenomic Approach To Identify Novel Mycobacterium leprae Antigens with Potential To Improve Immunodiagnosis of Infection

From Genome-Based In Silico Predictions to Ex Vivo Verification of Leprosy Diagnosis

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