Identification of H-2~d Restricted Th Epitope in Hepatitis E Virus Particulate Vaccine HEV 239

Recombinant particulate hepatitis E virus(HEV) vaccine HEV 239 is a potential candidate of poly-valent vaccine vector.In this paper,a dominant H-2~d restricted Th epitope in HEV 239 was identified.Groups of BALB/c mice were subcutaneously(s.c.) immunized twice by 50μg HEV 239 protein mixed with complete Freund's adjuvant(239-CFA).A peptide library covering the whole HEV 239 protein,containing 46 peptides with 10 amino acids overlapping,was synthesized and used to stimulate the spleen cells separated from the immunized mice in vitro. IFN-γ-ELISPOT assay results showed that P34(HEV PORF2 533-547aa,HSKTF FVLPL RGKLS)could stimulate the spleen cells to produce 413 spots/million spleen cells which was similar to HEV 239 protein.Thus,the peptide P34 was identified as a dominant H-2~d restricted T cell epitope.After depletion of the CD4~+ T cells in the immunized spleen cells by magnetic bead separation,the IFN-γ spots/million spleen cells decreased to the background level while almost no influence was observed after CD8~+ T cell depletion.This result showed that P34 was a H-2~d restricted Th epitope.