[Screening and identification of HLA-A0201 restricted cytotoxic T lymphocyte epitopes from hepatitis B virus E antigen in vitro]

To identify HLA-A0201 restricted cytotoxic T lymphocyte (CTL) epitopes derived from the hepatitis B virus e (HBe) antigen, for future use in a specific immunotherapy based on the identified epitope(s).

HBe gene sequences from the hepatitis B virus serotypes with the highest frequencies in China were analyzed by bioinformatic web-based interfaces for quantitative motif prediction, extended motif prediction, and peptide super-motif prediction. Four candidate peptides were identified: HBe1, HBe2, HBe3, and HBe4. The affinities of each were tested in vitro with T2 cells, which lack the transporter-associated with antigen transport (TAP) protein but express low levels of the MHC class I surface molecule, and measured by the T2 binding assay and DC50 assay. Flow cytometry was used to detect the fluorescence index of control and experimental groups.

The peptides HBe1 (LLWFHISCL), HBe2 (YLVSFGVWI), HBe3 (CLTFGRETV), and HBe4 (DLLDTASAL) were identified and tested as candidate targets. HBe2 and HBe3 showed higher HLA-A0201 affinity. HBe1, HBe2, and HBe3 showed better binding stability.

Two peptides based on HBe antigen, YLVSFGVWI and CLTFGRETV, possess both sufficient binding affinity and stability and may represent useful HLA-A0201-restricted CTL epitopes. Further study is needed to determine the immunogenic properties of these two peptides in vivo.