OBJECTIVETo prepare Sj14-3-3 DNA vaccine and observe its immunoprotection against Schistosoma japonicum in mice.

METHODSThe Sj14-3-3 gene was amplified by reverse transcription-polymerase chain reaction (RT-PCR) and subcloned into eukaryotic expression vector pBK. The recombinant plasmid pBK-Sj14-3-3 was extracted, purified and inoculated into BALB/c mice by intramuscular injection. Mice were attacked by Schistosoma japonicum cercariae and then killed. Adult worm and egg were counted, respectively. Diameter of the egg granulomas in the liver of infected mice was measured.

RESULTSElectrophoresis on 1% agarose gel showed that the product of RT-PCR and the inserted fragment of recombinant plasmid digested with EcoR I and Xho I had the same size, about 765 bp, confirming the latter was the 14-3-3 encoding gene by nucleotide sequencing. Adult worm load declined by 27%, average egg load of per gram (EPG) of the liver tissues by 79%, average egg production per couple of adult worm (EPWP) by 51%, and mean diameter of egg granulomas by 29% in vaccinated mice.

CONCLUSIONThe recombinant plasmid pBK-Sj14-3-3 was successfully constructed, which had some immunoprotection against Schistosoma japonicum in infected mice, indicating its potential to be vaccine candidate molecule of Schistosoma japonicum.