Objective To design and testify a novel strategy for acquiring mimetic epitope mapping by screening for a phage random peptide library using polyclonal anti keratin autoantibodies (AK auto Ab). Methods AK auto Ab were isolated and purified from pooled human sera by keratin affinity column in which keratin had been linked with CNBr Sepharose 4B,then biotinylated by the biotin ester. A 15 mer phage random peptide library was biopanned for 3 cycles and positive clones were identified by ELISA,competition assay and DNA sequencing. ResultsBy sequence comparison 23 positive clones were selected randomly and three epitopes were confirmed. Among the three epitopes SLSPMPTTNRR was the dominant epitope. The phages carrying positive clones reacted with AK auto Ab specifically and keratin could prevent interaction between AK auto Ab and positive phages. Conclusion The designed strategy is successfully applied in acquiring epitopes of polyclonal autoantibodies to keratin, which could provide a new approach for the discovery of epitope mapping which binds to natural autoantibodies.

Aim To study the mimicry peptide of JEV E protein by screening a phage 15-mer peptide library with anti-JEV E protein mAb 2H4. Methods After three rounds biopanning, the enriched positive phage clones were identified by ELISA. 10 positive phage clones were sequenced and compared homologously with JEV E protein. Results The short peptide displayed on screened positive phage could bind specifically to mAb 2H4, and the binding could be inhibited by natural JEV Ag. Amino acid sequences of the 10 positive phage clones were consensus, that is, RQDPQWPYANSTIAR. By homology analysis, two higher homologous sequences STXAR and WXXAXST were found in different regions of JEV E protein. The peptide displayed on positive phage could react specifically with the mouse antiserum against natural JEV Ag . Conclusion This peptide displayed on positive phage may mimic partial antigenicity of JEV E protein.