[Comparison between two expression ways on cysteine protease of Clonorchis sinensis].

Objective: To compare the prokaryotic expression system and eukaryotic expression system for the expression of cysteine protease of Clonorchis sinensis, and the diagnostic efficiency of their objective products.

Methods: According to the sequence of cysteine protease of C. sinensis, two pairs of primers were designed to amplify the genes from the total cDNA of C. sinensis. The genes were cloned into plasmid pET28a (+) and pPIC9K, respectively, and these recombinant plasmids were transformed into E. coli BL21 and GS115 separately after they were identified through double digests and sequencing. The cysteine protease of C. sinensis was expressed and purified, and then the sero-diagnostic effects of the purified proteins for clonorchiasis by ELISA were compared.

Results: The cysteine protease of C. sinensis was expressed as inclusion bodies in BL21, and its yield was 6.8 mg/L, while it was expressed as a kind of soluble protein in GS115, and its yield reached to 65.00 mg/L. Their sensitivities for serodiagnosis of clonorchiasis were 95.00% and 93.30%, respectively, and their specifities were 91.67% and 94.10%, respectively, with no statistically significant differences between them (all P values were above 0.05).

Conclusion: The application value on cysteine protease of C. sinensis expressed through eukaryotic expression system is higher than that expressed through prokaryotic expression system.