Identification of human T-cell epitopes on Mycobacterium tuberculosis small molecular weight proteins and development of DNA vaccines based on the epitopes

点击翻译按钮获取中文摘要

CD8^+ cytotoxic T lymphocytes (CTL) play a pivotal role in protection against Mycobacterium tuberculosis infection. We identified a novel CTL epitope on a protective antigen of M. tuberculosis, MPT51, in HLA-A^*0201-transgenic HHD mice. HHD mice were immunized with plasmid DNA encoding MPT51 using gene gun and interferon (IFN)-y production from the immune splenocytes was analyzed. In response to synthetic overlapping peptide library covering the mature MPT51 sequence, only one peptide, p51-70, stimulated the splenocytes to produce IFN-y. Three-color flow cytometric analysis of cell-surface CD4 and CD8 staining revealed that p51-70 peptide contains an immunodominant CD8^+ T-cell epitope. Further analysis using computer-assisted algorithms permitted identification of a bona fide T-cell epitope, p53-62. MHC class I stabilization assay using T2 cells confirmed that the epitope is presented by HLA-A^*0201. MPT51 p53-62/HLA-A^*0201 tetramer was observed to bind to the specific CD8^+ T cells of immune HHD splenocytes. In addition, MPT51 p53-62-specific memory CD8^+ T cells were found in tuberculin skin test-positive HLA-A^*0201^+ healthy individuals. This HLA-A^*0201-restricted CD8^+ T-cell epitope would be feasible for analysis of the role of MPT51-specific T cells in protective immunity and for future vaccine design against M. tuberculosis infection.