Amongst the identified epitopes, all NP epitopes are categorized as HLA-B types. We decided to examine the NP epitope binding specificity of HLA-A*0201 to CD8+ T cells. A desirable peptide sequence for inducing cytotoxic T-cell response should be presented as an endogenous peptide epitope through proteasome digestion and have a high binding affinity towards human MHC class-I molecules. Therefore, apart from the T2-cell binding assay, the stimulating ability of the predicted peptides was also accessed via an in vitro stimulation using human PBMC. In vitro stimulation was carried out by priming the T cells with the naturally processed NP peptides from autologous DC. Our results showed that the NP189 peptide stimulated the strongest immune response amongst the four peptides used. The binding affinity of NP158 in the T2-cell binding assay was relatively high but no significant change in the immune response was observed during in vitro administration of human PBMC, and the result produced was similar to the negative control. This suggests that the peptide prediction software can only give a computational estimation of immunogenicity of potential vaccine candidates. Hence, the predicted epitopes may not truly reflect experimental conditions in vitro nor mimic the real state in vivo. Natural processing and peptide presentation on the HLA molecule significantly contribute to the magnitude of the immune response [5, 8] . In our experiment, the number of CD8+ T cells detected via intracellular cytokine staining was not as high as expected compared to the whole pool of CD8+ T cells. In normal natural processing, all epitopes on NP-loaded DC are presented to the CD8+ T cells, based on the cross-presentation characteristics of the DC [4, 16, 27] . Therefore all activated CD8+ T cells should be responsive to the immunogenic epitopes presented on NP. In our experiment, our target cells were loaded with only a single type of the target peptide which may explain why such a low percentage of cell activation caused by the corresponding peptide-specific CD8+ T cells is observed.