[Cloning, expression and immunodiagnostic evaluation of antigen EPC1 from Echinococcus granulosus].

Objective: To clone and express EPCl gene of Echinococcus granulosus, and investigate its immunogenicity and diagnostic value.

Methods: Total RNA was extracted from hydatid cyst protoscoleces and EPC1 gene of Echinococcus granulosus was amplified by RT-PCR. The PCR product was cloned into pGEM-T vector, and then subcloned into the prokaryotic expression vector PET28a(+). The positive recombinants were transformed into Escherichia coli BL21 (DE3), and followed by expression of the protein induced by IPTG. The recombinant protein was identified by SDS-PAGE and Western blotting, and used to establish ELISA. Serum samples from patients with cystic echinococcosis (60 cases), alve-olar echinococcosis (37 cases), cysticercosis (16 cases), clonorchiasis sinensis (7 cases), schistosomiasis japonica (4 cases) and healthy persons (33 cases) were examined.

Results: The recombinant plasmid PET28a-EgEPC1 was identified by restriction enzyme digestion and sequencing. SDS-PAGE result showed that the recombinant containing recombinant plasmid PET28a-EgEPC1 expressed a soluble fission protein of EgEPC1 (about M, 11 000). The protein was recognized by pool sera of cystic echinococcosis patients. The overall sensitivity and specificity of diagnosis by ELISA for cystic echinococcosis were 78.3% (47/60), and 98.3% (59/60), respectively. The cross reaction with sera of alveolar echinococcosis was 40.5% (15/37).

Conclusion: The recombinant EgEPC1 antigen has diagnostic value in cystic echinococcosis.