Abstract:

【Objective】 The present study was intended to clone a cDNA encoding cyclophilin A in Schistosoma japonicum and subsequently investigate its molecular functions as well as immunoprotective potential as a vaccine candidate for schistosomasis . 【Method】 Polymerase chain reaction (PCR) technique was employed to amplify the full-length cDNA encoding cyclophilin A of schistosomula (Sj CyPA) by employing a schistosomula specific enrichment cDNA library as the template. The expression profiles of Sj CyPA were determined at several different development stages by using real-time RT-PCR. The cDNA containing the open reading frame (ORF) of CyPA was subcloned into a pET28a(+) vector and the recombinant plasmid was transformed into competent E.coil/BL21 for producing recombinant protein. The PPIase activity of recombinant protein was determined by chymotrypsin-coupled chromogenic assay, and its antigenicity was confirmed by Western blot. The immunoprotective potential immunized by recombinant Sj CyPA in mice was also evaluated in the present study. 【Result】 The length of cDNA containing Sj CyPA ORF is 519 base pairs, encoding 172 amino acids. As determined by real-time PCR, the highest expression of Sj CyPA was observed at the transcript level at 13-day schistosomula stage, indicating that Sj CyPA was a abundant expression gene at schistosomula stage. The expressions of Sj CyPA both at transprict level and at protein level were not significantly alternated upon the treatment by cyclosporin A as determined by real time PCR and Western blot. Expectly, chymotrypsin- coupled chromogenic assay confirmed that Sj CyPA had PPIase activity and Western blot indicated that Sj CyPA was able to induce specific antibodies. Additionally, animal experiment showed that 18.72% worm reduction and 44.6% egg reduction were achieved in mice vaccinated with recombinant CyPA protein, respectively. 【Conclusion】 A full-length cDNA encoding Sj CyPA was obtained and its molecular characterizations were preliminarily investigated. Moreover, it was observed that the vaccination of recombinant protein of Sj CyPA could induce certain potential against schistosome schistosomasis.

Key words: Schistosoma japonnicum, CyclophilinA (Sj CyPA), gene clone and expression, PPIase activity, immunoprotective effect