The Screening Of Minmetic Oligo-peptide Of JEV E Glycoprotein From Random Peptide Library

Japanese encephalitis (JE) is an acute central nerve system infection caused by Japanese encephalitis virus (JEV), which is endemic in Southeast Asia. Vaccinating is an efficient measure to control JE incidence in epidemic areas. However, the JE vaccines applied in the world are not good enough. The early formalin-inactivated JE vaccine, purified from infeted mouse brain, infrequently induced side-effects and requires three doses. Attenuated live vaccine avoids the disadvantages of inactivated JE vaccine, but has the possibility of virulence reversion. Therefore, it is necessary to develop novel vaccines against JEV with safety and effectiveness. The envelope (E) glycoprotein, the major structure protein of JEV and major component to induce protective immunity, become the primary target for vaccine development. Although in recent years there were some helpflul achievements in the study of subunit vaccine and recombinant DNA vaccines against JEV, the development of these novel vaccines are limited by the unclear knowledge about epitopes of E protein. Phage random peptide library (RPL) technique has recently become a powerful tool to explore interactive sites between receptors and ligands, seek high affinity bioactive ligands, detect discontinuous epitopes of unknown protein, and now is applied widely in the fields of vaccine development, new drug discovery and diseases diagnosis. A great number difference peptides of RPL may be the mimic peptide of target antigen, which provide a new research method to confirm sequence of protein epitope. The specific peptides screened from RPL with mAb may identify the combined sites of mAb or be used as virus protective antigen, which can be beneficial to researching structure and function of virus key epitopes, even to designing novel vaccine. To investigate the mimic peptide of JEV E protein, two mAbs (2114 and 2F2 )against JEV E protein with strong protective activity have been used to screen from a 1 5-mer phage random peptide library . Two 1 5-mer peptides from the 1 5-mer peptide library, named m2H4 (RQDPQWPYANSTIAR) and m2F2 (HTPQWSPSQYRPSLR) can specifically react with 2H4 arid 2F2, respectively, and the reaction could be inhibited by JEV native antigen. By homologous analysis, two consensus sequences, STXAR and PXXSPS may be the mimotope recognized by 2H4 and 2F2, respectively. The pliage- displayed m2H4 and m2F2 can elicit antibody in the serum of mice against m2H4 and m2F2, respectively. Moreover, m2H4 and 2F2 can specifically react with antibodies in the serum of mice induced by JEV native antigen. In summary, these two phage-displayed oligo peptides may be used as mimic peptides of JEV E protein and provide some helpful clue for the development of novel JE vaccine.