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For further research of the apoptosis mechanism of Schistosoma japonicum (S. japonicum). The cDNA encoding Sjcaspase3 of Schistosoma japonicum was amplified by polymerase chain reaction (PCR) technique, which contained 900 nucleotides and encoded 299 amino acids. The theory molecular weight and isoelectric point (PI) of the deduced protein is 33.5 kDa and 6.39, respectively. Real-time PCR was used to analyze the transcription profiles of Sjcaspase3 at different development stages of S. japonicum. The results showed that this gene was expressed in all stages of S. japonicum with the highest expression in 21d worms, and the level of gene transcription in 42 d female worms was higher than that of male worms. The recombinant plasmid pXJ40-FLAG-Sjcaspase3 was constructed and transfection into Hela cells successfully. Real-time PCR and Western blotting analysis showed Sjcaspase3 was successfully expressed in Hela cells. Enzyme activity analysis revealed that recombinant Sjcaspase3 possessed the activity to cut substrate DEVD. Flow cytometry proved that Sjcaspase3 could induce early apoptosis of Hela cells. The results provide the basis for proceeding further study on the biological function of Sjcaspase3 and better understand the apoptosis mechanism of S. japonicum.

To identify SJCHGC01743 gene of Schistosoma japonicum and evaluate the potential of the recombinant protein as a new vaccine candidate for schistosomiasis, polymerase chain reaction (PCR) technique was used to amplify the cDNA of the gene and real-time RT-PCR was used to analyze the transcription profiles of SJCHGC01743 at different development stages. Recombinant plasmid was successfully constructed and transformed into competent Escherichia coli BL21 (DE3). Then the recombinant protein was expressed, purified and emulsified with ISA206 adjuvant to immunize BALB/c mice for three times. The immunogenicity was confirmed by Western blotting and tissue localization was detected by indirect immunofluorescent assay. The specific antibody level was detected by ELISA. The immunoprotection of rSjOST48 was evaluated by the reduction in worm and egg counts in mice. A cDNA with 1 248 nucleotides was isolated from 28-day-old schistosomes cDNAs by PCR. Sequence analysis revealed that SJCHGC01743 was a 48-kDa subunit of the oligosaccharyltransferase complex (OST48) and named as SjOST48. Real-time PCR analysis indicated that this gene was expressed in all investigated stages and had the highest expression level in 28 d worms, the level of gene transcription in female worms was significantly higher than that of male worms. Then recombinant plasmid pET28a(+)-SjOST48 was successfully constructed and expressed in E. coli BL21 (DE3). Western blotting analysis showed that rSjOST48 had good immunogenicity. Indirect immunofluorescent analysis revealed that SjOST48 was mainly distributed on the tegument of the worms. The result of ELISA indicated that the rSjOST48 vaccinated group could induce a significant increase in the level of specific IgG, IgG1 and IgG2a. An immunoprotection experiment showed that the vaccination of rSjOST48 in mice induced 32.62% (P < 0.05) reduction in the numbers of worms and 57.61% (P < 0.01) in eggs in liver, compared with that of the control group. This study provides the foundation for proceeding further research on the biological function of SjOST48 and screening new vaccine candidates for schistosomiasis.

Radiation sensitive protein 23 (RAD23) is a nucleotide excision repair (NER) protein that plays an important role in Ubiquitin-proteasome pathway (UPP). Schistosoma japonicum radiation sensitive protein23 (SjRAD23) cDNA sequences were amplified by PCR and cloned into pET28a (+) vector to construct recombinant expression plasmid pET28a(+)-SjRAD23. The recombinant protein was expressed as both inclusion bodies and the supernatant in Escherichia coli BL21 (DE3) cell. Immunofluorescence observation shows that SjRAD23 was mainly distributed on the tegument surface of the worms. ELISA assay reveals that specific IgG, IgG1 and IgG2a antibodies could be detected in the sera of rSjRAD23 immunized mice. Western blotting analysis shows that the recombinant SjRAD23 could be recognized by serum specific to soluble adult worm antigen of S. japonicum. BALB/c mice vaccinated with rSjRAD23 combined with 206 adjuvant revealed 35.94% worm reduction and 40.59% liver egg reduction when compared with that of the adjuvant control