Abstract: 　Objective To clone and express the cDNA encoding Schistosoma japonicum tropomyosin. Methods The cDNA was amplified by reverse transcription polymerase chain reaction (RT PCR). The PCR products were ligated with pGEM T vectors and then for transformations. After characterization of white clones by agarose gel electrophoresis, endonucleases digestion and PCR, some recombinant plasmids with inserts were used for sequencing. Then the gene was subcloned into prokaryotic expression vector pQE30 and expression was induced by IPTG. Results The PCR products was 823 bp judged by agarose gel electrophoresis and sequencing. A cDNA encoding S japonicum tropomyosin, except for 14 amino acids at the amino terminus and 2 at the carboxyl terminus, has been constructed and cloned successfully. The colony, designated pGSjcTM12, was sequenced and shown to be 91 1% identical at the nuclei acid level and 98.1% identical in deduced amino acid sequence to that of S mansoni tropomyosin. The gene was subcloned into pQE30 and an expressed protein of about 32 kDa was obtained.Conclusion The cloning and expression of the gene encoding S japonicum tropomyosin had been successfully made.

Key words: Schistosoma japonicum (Chinese strain), tropomyosin, RT PCR, molecular cloning, cDNA sequence, expression