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Identification of an HLA-A*0201-Restricted T-Cell Epitope on the MPT51 Protein, a Major Secreted Protein Derived from Mycobacterium tuberculosis, by MPT51 Overlapping Peptide Screening

Aoshi, Taiki, Nagata, Toshi, Suzuki, Mina, Uchijima, Masato, Hashimoto, Dai, Rafiei, Alireza, Suda, Takafumi, Chida, Kingo, Koide, Yukio
Infection and immunity 2008 v.76 no.4 pp. 1565-1571
CD8-positive T-lymphocytes, Mycobacterium tuberculosis, algorithms, epitopes, flow cytometry, interferon-gamma, major histocompatibility complex, mice, plasmids, screening, splenocytes, synthetic peptides, tuberculin, tuberculosis, vaccine development
CD8⁺ T cells play a pivotal role in protection against Mycobacterium tuberculosis infection. We identified a novel HLA-A*0201-restricted CD8⁺ T-cell epitope on a dominant secreted antigen of M. tuberculosis, MPT51, in HLA-A*0201 transgenic HHD mice. HHD mice were immunized with plasmid DNA encoding MPT51 with gene gun bombardment, and gamma interferon (IFN-γ) production by the immune splenocytes was analyzed. In response to overlapping synthetic peptides covering the mature MPT51 sequence, the splenocytes were stimulated to produce IFN-γ by only one peptide, p51-70. Three-color flow cytometric analysis of intracellular IFN-γ and cell surface CD4 and CD8 staining revealed that the MPT51 p51-70 peptide contains an immunodominant CD8⁺ T-cell epitope. Further analysis using computer algorithms permitted identification of a bona fide T-cell epitope, p53-62. A major histocompatibility complex class I stabilization assay using T2 cells confirmed that this epitope binds to HLA-A*0201. The T cells were capable of lysing MPT51 p53-62 peptide-pulsed T2 cells. In addition, MPT51 p53-62-specific memory CD8⁺ T cells were found in tuberculin skin test-positive HLA-A*0201⁺ healthy individuals. Use of this HLA-A*0201-restricted CD8⁺ T-cell epitope for analysis of the role of MPT51-specific T cells in M. tuberculosis infection and for design of vaccines against tuberculosis is feasible.