PLoS ONE (Jan 2013)

A novel B-cell epitope identified within Mycobacterium tuberculosis CFP10/ESAT-6 protein.

  • Hua Yang,
  • Haizhen Chen,
  • Zhonghua Liu,
  • Hui Ma,
  • Lianhua Qin,
  • Ruiliang Jin,
  • Ruijuan Zheng,
  • Yonghong Feng,
  • Zhenling Cui,
  • Jie Wang,
  • Jinming Liu,
  • Zhongyi Hu

DOI
https://doi.org/10.1371/journal.pone.0052848
Journal volume & issue
Vol. 8, no. 1
p. e52848

Abstract

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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.