[Identification of epitope of 22.6 kDa antigen of Schistosoma japonicum with phage-displayed random peptide library].

Objective: To identify the epitopes of 22.6 kDa antigen of Schistosoma japonicum (Sj22.6).

Methods: A 12-mer library displayed on pIII of fd phage was used to screen the epitopes of Sj22.6 with the purified multiple clone IgG antibody against the Sj22.6 antigen. Five rounds of biopanning were carried out and fourteen clones from the fifth round biopanning were randomly selected and identified by Western blotting. The mice were immunized with the obtained positive clones and the antibody titers of sera from the mice were detected. The clones which could stimulate the mice to produce anti-Sj22.6 antibodies were sequenced and their amino acid sequences were compared with that of Sj22.6.

Results: Six clones selected from the fourteen ones could stimulate the mice to produce anti-Sj22.6 antibodies analysed by Western blotting. The amino acid sequence of one epitope showed high homology with Sj22.6.

Conclusion: Four epitopes of Sj22.6 were obtained. One may be a structure epitope and the other three were mimic epitopes.