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Updated: May 15, 2026
Peptide Scanning-assisted Identification of a Monoclonal Antibody-recognized Linear B-cell Epitope
Published on: March 24, 2017
A novel B-cell epitope identified within Mycobacterium tuberculosis CFP10/ESAT-6 protein
Hua Yang1, Haizhen Chen, Zhonghua Liu
1Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.
Insights
Researchers identified a specific B-cell epitope (E5 peptide) on the CFP10/ESAT-6 (CE) protein complex, crucial for tuberculosis (TB) diagnosis. This finding may lead to improved serodiagnostic tools for TB patients.
Area of Science:
- Immunology
- Microbiology
- Biochemistry
Background:
- The CFP10/ESAT-6 (CE) protein complex is vital in mycobacterial pathogenesis and differentiating TB patients from BCG-vaccinated individuals.
- Previous studies analyzed B-cell epitopes of CFP10 and ESAT-6 separately, but CE protein epitopes remained unclear, particularly within the ESAT-6 40-62 region.
Purpose of the Study:
- To identify B-cell epitopes of the CE protein complex.
- To investigate the precise epitope within the ESAT-6 40-62 region.
- To evaluate the diagnostic potential of identified epitopes for tuberculosis.
Main Methods:
- Phage-display library biopanning using anti-CE polyclonal antibodies.
- Sequence alignment, binding affinity, and specificity detection of identified epitopes.
- Generation of polyclonal mouse sera and analysis of TB patient sera.
Main Results:
- A linear B-cell epitope, E5 peptide (KWDAT), was identified, corresponding to the 57th-61st sequence of ESAT-6.
- Antibody titers binding to the E5 peptide were significantly higher in TB patients compared to healthy individuals.
Conclusions:
- A B-cell epitope for the CE protein complex, specifically within the ESAT-6 40-62 region, has been identified.
- The E5 peptide shows potential utility in the serodiagnosis of tuberculosis, warranting further validation with larger sample sizes.
Background:
The 10-kDa culture filtrate protein (CFP10) and 6-kDa early-secreted target antigen (ESAT-6) play important roles in mycobacterial virulence and pathogenesis through a 1:1 complex formation (CFP10/ESAT-6 protein, CE protein), which have been used in discriminating TB patients from BCG-vaccinated individuals. The B-cell epitopes of CFP10 and ESAT-6 separately have been analyzed before, however, the epitopes of the CE protein are unclear and the precise epitope in the positions 40 to 62 of ESAT-6 is still unknown.
Methods:
In the present study, we searched for the B-cell epitopes of CE protein by using phage-display library biopanning with the anti-CE polyclonal antibodies. The epitopes were identified by sequence alignment, binding affinity and specificity detection, generation of polyclonal mouse sera and detection of TB patient sera.
Results:
One linear B-cell epitope (KWDAT) consistent with the 162(nd)-166(th) sequence of CE and the 57(th)-61(st) sequence of ESAT-6 protein was selected and identified. Significantly higher titers of E5 peptide-binding antibodies were found in the sera of TB patients compared with those of healthy individuals.
Conclusion:
There was a B-cell epitope for CE and ESAT-6 protein in the position 40 to 62 of ESAT-6. E5 peptide may be useful in the serodiagnosis of tuberculosis, which need to be further confirmed by more sera samples.
