Abstract: 　Objective To identify the T cell epitopes on 22.6kDa antigen of Schistosoma japonicum (Sj22.6). Methods The primary structure of Sj22.6 molecule was analysed using various predictive algorithms and a panel of 4 peptides were acquired. Their oligonucleotides were designed, synthesized and inserted into the multiple cloning site of plasmid pET-32c(+). The recombinant plasmids were transformed into E.coli BL21 and identified by endonuclease digestion and sequencing. The positive clones containing the recombinant plasmids could express specific fusion proteins (trx-epitope, MW≈20kDa) induced by IPTG. The fusion protein with 6×His could be coupled with NTA resin specifically, and purified by elusion of the column with buffer containing imidazole. The purified fusion proteins were incubated with splenocytes of C3H mice and then, the proliferation of splenocytes was determined by~3H-TdR incorporation assay. Results The recombinant plasmids were constructed successfully and the positive clones containing the recombinant plasmids expressed specific fusion proteins. Three of the purified fusion proteins (P4、P5、P6) could stimulate the lymphocyte proliferation. Conclusion Three T cell epitopes on Sj22.6 antigen were identified.

Key words: Schistosoma japonicum, 22.6 kDa antigen, T cell epitope, identification