Abstract: 　Objective To clone and express the structural gene encoding a 31 kDa antigen of Trichinella spiralis (Henan isolate) pre encysted larvae (TspE1). Methods On the Day 17 after being infected with Trichinella spiralis ,pre encysted larvae were collected and total RNA of the larvae was obtained.The target gene in the recombinant plasmid (pUC18/Ts HN3) was sub cloned into the prokaryotic expression vector pGEMEX 1 and the recombinant pGEMEX 1/Ts HN3 was constructed. After IPTG induced incubation, the fusion protein was expressed in E.coli JM109(DE 3)competent cells, analysed by SDS PAGE and identified by Western blotting. Results The results of SDS PAGE demonstrated that the target gene was efficiently expressed and the level of expression peaked at 4 h post incubation. The molecular weight of the recombinant protein was 31 kDa. The portion of the fusion protein accounted for 26% of all the proteins by thin layer gel optical scanning. The fusion protein could be recognized by sera from rats infected with Trichinella spiralis and from patients with trichinellosis. Conclusion The gene encoding a 31 kDa antigen of Trichinella spiralis ( Henan isolate) pre encysted larvae ( TspE1) was cloned and expressed successfully in prokaryotic vector.

Key words: Trichinella spiralis (Henan isolate), pre encysted larvae, 31 kDa antigen, molecular cloning, expression