title: A novel strategy to screen Bacillus Calmette-Guérin protein antigen recognized by γδ TCR.
abstract: BACKGROUND
  Phosphoantigen was originally identified as the main γδ TCR-recognized antigen that could activate γδ T cells to promote immune protection against mycobacterial infection. However, new evidence shows that the γδ T cells activated by phosphoantigen can only provide partial immune protection against mycobacterial infection. In contrast, whole lysates of Mycobacterium could activate immune protection more potently, implying that other γδ TCR-recognized antigens that elicit protective immune responses. To date, only a few distinct mycobacterial antigens recognized by the γδ TCR have been characterized.
  
  
  RESULTS
  In the present study, we established a new approach to screen epitopes or protein antigens recognized by the γδ TCR using Bacillus Calmette-Guérin- (BCG-) specific γ TCR transfected cells as probes to pan a 12-mer random-peptide phage-displayed library. Through binding assays and functional analysis, we identified a peptide (BP3) that not only binds to the BCG-specific γδ TCR but also effectively activates γδ T cells isolated from human subjects inoculated with BCG. Importantly, the γδ T cells activated by peptide BP3 had a cytotoxic effect on THP-1 cells infected with BCG. Moreover, the oxidative stress response regulatory protein (OXYS), a BCG protein that matches perfectly with peptide BP3 according to bioinformatics analysis, was confirmed as a ligand for the γδ TCR and was found to activate γδ T cells from human subjects inoculated with BCG.
  
  
  CONCLUSIONS
  In conclusion, our study provides a novel strategy to identify epitopes or protein antigens for the γδ TCR, and provides a potential means to screen mycobacterial vaccines or candidates for adjuvant.
authors.affiliation: State Key Laboratory for Molecular Virology and Genetic Engineering, Institute of Pathogen Biology, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China.
authors.forename: XueYan
authors.initials: X
authors.lastname: Xi
authors.forename: XiaoYan
authors.initials: X
authors.lastname: Zhang
authors.forename: Bei
authors.initials: B
authors.lastname: Wang
authors.forename: Ji
authors.initials: J
authors.lastname: Wang
authors.forename: He
authors.initials: H
authors.lastname: Huang
authors.forename: LianXian
authors.initials: L
authors.lastname: Cui
authors.forename: XiQin
authors.initials: X
authors.lastname: Han
authors.forename: Liang
authors.initials: L
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: He
authors.forename: ZhenDong
authors.initials: Z
authors.lastname: Zhao
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry / Q000276:immunology*; D001426:Bacterial Proteins / Q000737:chemistry / Q000276:immunology*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology; D005260:Female; D006801:Humans; D008213:Lymphocyte Activation / Q000276:immunology; D008297:Male; D008969:Molecular Sequence Data; D009163:Mycobacterium bovis / Q000276:immunology*; D019151:Peptide Library; D010455:Peptides / Q000737:chemistry / Q000276:immunology; D011485:Protein Binding; D016692:Receptors, Antigen, T-Cell, gamma-delta / Q000276:immunology*; D015203:Reproducibility of Results; D017386:Sequence Homology, Amino Acid; D013601:T-Lymphocytes / Q000276:immunology; D014162:Transfection; D014611:Vaccination; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D000939:Epitopes; D019151:Peptide Library; D010455:Peptides; D016692:Receptors, Antigen, T-Cell, gamma-delta