OBJECTIVETo clone the coding gene of the stage-specific antigen cC1 from Cysticercus cellulosae and express high levels of soluble cC1 in E.coli.

METHODSThe cC1 gene was amplified from Cysticercus cellulosae by RT-PCR and cloned into pMD18-T vector, followed by subcloning into the prokaryotic expression plasmid pET28a. The recombinant plasmid was transformed into E.coli BL21(DE3) and the expression conditions were optimized. The expressed product was purified by Ni(+)-affinity chromatography, analyzed by high-performance liquid chromatography (HPLC), and identified with SDS-PAGE and Western blotting.

RESULTSThe fragment length of the amplification product by RT-PCR was 1056 bp. Comparison of the amplified gene sequence with the cC1 gene in Genbank identified a samesense point mutation at 423 position in the gene cloned into the expression plasmids. After a 6-h induction with 0.05 mmol/L IPTG at 37 degrees celsius;, the expression of the 40 kd soluble fusion protein exceeded 60% of the total bacterial protein, and the fusion protein was recognized by Cysticercus-infected human sera. The purity of the fusion protein was about 94% after purification by affinity chromatography.

CONCLUSIONThe stage-specific antigen cC1 from Cysticercus cellulosae has been successfully cloned and the soluble protein efficiently expressed in E.coli, which provides the basis for its further study and application.