title: A novel B-cell epitope identified within Mycobacterium tuberculosis CFP10/ESAT-6 protein.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors: Shanghai Key Laboratory of Tuberculosis, Shanghai Pulmonary Hospital, Tongji University School of Medicine, Shanghai, China.
authors: Hua
authors: H
authors: Yang
authors: Haizhen
authors: H
authors: Chen
authors: Zhonghua
authors: Z
authors: Liu
authors: Hui
authors: H
authors: Ma
authors: Lianhua
authors: L
authors: Qin
authors: Ruiliang
authors: R
authors: Jin
authors: Ruijuan
authors: R
authors: Zheng
authors: Yonghong
authors: Y
authors: Feng
authors: Zhenling
authors: Z
authors: Cui
authors: Jie
authors: J
authors: Wang
authors: Jinming
authors: J
authors: Liu
authors: Zhongyi
authors: Z
authors: Hu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D000942:Antigens, Bacterial / Q000032:analysis / Q000276:immunology*; D018985:Epitopes, B-Lymphocyte / Q000032:analysis* / Q000276:immunology*; D005260:Female; D006801:Humans; D051379:Mice; D008807:Mice, Inbred BALB C; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009169:Mycobacterium tuberculosis / Q000737:chemistry / Q000276:immunology* / Q000472:pathogenicity*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D016415:Sequence Alignment; D014376:Tuberculosis / Q000097:blood / Q000276:immunology / Q000382:microbiology*
chemical_list: D000907:Antibodies, Bacterial; D000942:Antigens, Bacterial; D018985:Epitopes, B-Lymphocyte; D019151:Peptide Library; D010455:Peptides; C072681:Mycobacterium tuberculosis antigens