It was subsequently cloned into a pBudCE4.1 vector (Invitrogen). Plasmids encoding different peptide sequences were constructed by adding the corresponding DNA fragments after the leader sequence of the HHD using PCR with the following primers: sense (NP158: 5 0 -ATCGACCGGTCTATATGCTGG AATGGACCCTCGGATGTGTTCCCTGGGAGGA GGTGCTAG-3 0 , NP189: 5 0 -ATCGACCGGTCTATA TGCTATGGTGATGGAGCTGATCAGAATGATCG GAGGAGGTGCTAG-3 0 , NP373: 5 0 -ATCGACCGG TCTATATGCTGCCATGGACAGCAACACCCTGG AGCTGGGAGGAGGTGCTAG-3 0 , NP458: 5 0 -ATC GACCGGTCTATATGCTTTCCAGGGACGGGGA GTGTTCGAGCTGGGAGGAGGTGCTAG-3 0 ) and antisense (5 0 -ATCGCTCGAGTCACGCTTTACAAT C-3 0 ) primers. The constructed fragments were cloned into HHDpBudCE4.1 at Age I and Xho I sites. The N220HHDpBudCE4.1 expressing an identified HLA-A*0201 epitope (N220) was used as a control plasmid [2] .