[Cloning, expression and immunogenicity analysis of cathepsin L-like protease of Fasciola hepatica].

Objective To clone and express the cathepsin L-like protease gene of Fasciola hepatica (FhCL) and investigate the immunogenicity of the recombinant FhCL protein. Methods Specific primers were designed according to the reported FhCL gene in GenBank. Using total RNA from adult worms of F. hepatica, FhCL gene was amplified by RT-PCR. The PCR product was cloned into pMD18-T vector and then subcloned into pET30a(+) vector. The recombinant plasmid was transformed into E. coli BL21 (DE3) and followed by expression of the protein induced by IPTG. The ex- pression situation of recombinant FhCL was analyzed by SDS-PAGE. Its immunoresponse to the sera of infected goat and the antisera of SD rats against FhCL was examined by Western blotting analysis. Results PCR and double enzyme di- gestion showed that the FhCL gene fragment was about 1 000 bp in length. The constructed recombinant plasmid pET30a (+)-FhCL was identified by sequencing. The recombinant protein (Mr 42 000) was expressed in the form of inclusion body. The protein was recognized respectively by the sera of infected goat and the sera from rat immunized with FhCL. Conclusion The recombinant plasmid pET30a(+)-FhCL has been constructed, which shows high antigenicity.