Here we describe, to our knowledge, the most TCRβ focused CD8 T cell response to date. This TCR is specific for a conserved Plasmodium-derived epitope in mice (GAP5041-48), presented by H-2Db. After various immunization regimens, >99% of epitope-specific CD8 T cells detected by tetramer staining expressed TCR Vβ8.1 (TRB). Interestingly, priming with dendritic cells coated with GAP5041-48 peptide resulted in the same TCR Vβ distribution, suggesting that the observed bias does not evolve with multiple antigen exposures. Additionally, DC-priming induced exceptionally strong responses only 4 days post-immunization (~20% of total CD8 T cells were tetramer positive), suggesting an unusually large antigen-specific naïve CD8 T cell repertoire. Currently, the upper limit for the size of antigen-specific naive CD8 T cell repertoire ranges from 600-1500 cells (VacV B8R, MCMV M45). We show that GAP5041-48-specific naïve CD8 T cell repertoire, with its size of ~2,200 cells, extends this upper limit by more than 40%. Finally, classical Ala-substitution screening of the peptide (SQLLNAKYL), showed that amino acids (aa) at positions 6 and 7 are critical for TCR recognition. This epitope could be used as a valuable tool for better understanding the relation between a TCR structure and thymic selection. Moreover, the unique property of GAP5041-48-specific response make it a powerful tool to study fundamental processes underlying CD8 T cell activation upon Plasmodium infection.