Abstract
The PPE (proline-proline-glutamic acid) proteins of Mycobacterium tuberculosis are characterized by a conserved N-terminal domain of approximately 180 amino acids and variable C-terminal domain. Since last decade, these proteins have gained much importance in the serodiagnosis of tuberculosis (TB) as they act as a source of antigenic variation. We have demonstrated earlier that one of the PPE proteins PPE17 (Rv1168c) induces strong B-cell and T-cell responses in active TB disease and also displays a higher antibody titer compared to immunodominant antigens such as ESAT-6, Hsp60 and PPD. However, the immunodominant domain of PPE17 (N-terminal or C-terminal) was not examined in detail. In the present study, we observed that antibody responses elicited in TB patients were directed mostly towards the N-terminal domain of PPE17 (N-PPE17). The antibody generated against N-PPE17 in TB patients did not significantly cross-react with N-terminal domains of other PPE proteins used in this study. Our data suggest that the N-terminal domain of PPE17 protein is immunodominant and could be used as a better serodiagnostic marker than the full-length PPE17 protein.
MeSH terms
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Adolescent
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Adult
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Antibodies, Bacterial / biosynthesis*
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Antigens, Bacterial / chemistry
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Antigens, Bacterial / genetics
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Antigens, Bacterial / immunology*
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / immunology
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Case-Control Studies
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Cross Reactions
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Female
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Humans
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Immunodominant Epitopes / chemistry
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Immunodominant Epitopes / genetics
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Male
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Middle Aged
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Mycobacterium tuberculosis / chemistry
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Mycobacterium tuberculosis / genetics
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Mycobacterium tuberculosis / immunology*
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Peptide Fragments / chemistry
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Peptide Fragments / genetics
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Peptide Fragments / immunology
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Protein Domains
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Serologic Tests
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Tuberculosis / diagnosis
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Tuberculosis / immunology*
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Tuberculosis / microbiology
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Young Adult
Substances
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Antibodies, Bacterial
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Antigens, Bacterial
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Bacterial Proteins
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Immunodominant Epitopes
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Peptide Fragments
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Rv1168c protein, Mycobacterium tuberculosis
Grants and funding
PRA was supported by the Research Associateship from the Indian Council of Medical Research, Government of India (80/796/2013-ECD). This work was supported by the Grants from Department of Biotechnology, Government of India (BT/PR11605/NNT/28/758/2014 and BT/PR12817/COE/34/23/2015). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.