The selected peptides were tested for their cytotoxic T cell stimulating ability in vivo using a HHD transgenic mouse model. HHD is a special mouse type which lacks mouse b 2 -microglobulin and MHC I, but contains human b 2 -microglobulin and HLA-A*0201 a-1, a-2, as well as a mouse a-3 fusion gene. This genetically modified mouse immune system can impersonate a human system's immune response to stimulation restricted to the reaction between HLA-A*0201 and T-cell receptors only, eliminating the background caused by mouse MHC class-I molecules [21] . In our experiment, cytotoxicity and ELISPOT assays showed that the NP373-381 AMDSNT-LEL and NP458-466 FQGRGVFEL are the most immunogenic peptides. The reactivity of the two peptides was consistent with all the tests during the process of epitope identification. Another target peptide, NP189, although it showed good responses in the T2-cell binding assay and in vitro stimulation of human CD8+ T cells, it induced a weak response in animal experiments. This is another indication that the in vitro system does not reflect the in vivo situation. Nonetheless, in vitro experiments are essential for acquiring basic information to verify the characteristics of these potential peptides and discovered immunogenic peptides, since the testing of the peptides cannot be performed in clinical trials without extensive investigation. The T2-cell binding assay is a good methodology for examining the potential binding affinity of the target peptides to the groove of HLA-A*0201 molecules. The antigen processing and presentation, and the magnitude of the CD8+ T-cell responses corresponding to the stimulants can be investigated via in vitro stimulation of the CD8+ T cells. We believe that the HHD transgenic mouse model is an appropriate animal model for investigating the stimulating effects of the peptide-HLA complex to the corresponding T-cell responses.