T Cell Epitope Analysis of Structural Protein of Adenovirus

Hwang, Jae Won; Kim, Mi Hyung; Kim, Kil Hyoun

Abstract

Thelper (Th) cells play a pivotal role in the regulation of immune responses. Since Th epitopes in adenovirus have not yet been defined, in this study, it was attempted to search for Th epitopes of adenovirus antigens that are restricted by MHC class II (H-2E). Among candidate viral proteins to be screened for Th epitopes, structural protein was selected, since they induced strong IL-2 release from adenovirus immune lyrnph node (LN) cells and the presence of E1 protein, which contains immunodominant cytotoxic T lymphocyte epitopes, did not potentiate the T cell responses. To confirm the presence of Th epitopes in the structural protein, virions were trypsinized and the resulting polypeptides whose molecular weights were lower than 5,000 were fractionated by HPLC. Some of the HPLC fraction turned out to induce LN cell proliferation. Ten synthetic peptides were designed as candidate Th epitopes from the primary amino acid sequences of adenovirus hexon and penton protein which are major constituents of the virion. The selected sequences share the common features of other known H-2E' binding ligands. Among these ten synthetic peptides, peptide of hexon protein amino acid residue 709-721 induced noticeable proliferation of LN cells from preimmune mice, and also able to induce IL-2 secretion from adenovirus-specific T hybridomas, suggesting that the peptide was the most immunodominant Th epitope. Hexon protein 221-233 and hexon protein 676-688 are considered as epitopes also. This study revealed three epitope sequences from adenovirus structural protein that are presented by class II MHC, H-2E.