SHEN Jijia, JIANG Zuojun and
YY Xinbing
Dept. of Parasitology, Anhui
Medical University Hefei 230032
Dept. of Parasitology, Sun-Yat-Sen University of Medical Sciences
Guangzhou
Objective: To screening new schistosome vaccine candidate,
Methods: S. japonicum adult cDNA library was screened using the mAb against membrane antigen of S. japonicum schistosomula, and also using sera from immune rabbits vaccinated with irradiated cercariae. Three different pieces of S. japonicum cDNA gene fragments were cloned into pGEM-T vector. The sequences of the inserts were determined using an automated DNA sequencer. One of the unknown gene (SjB8) was picked up and its ORF sequence (291 bp) was subcloned into pBK-CMV eukaryotic expression vector. pBK/SjGST recombinants was successfully constructed by the same methods. The recombinant plasmids were identified by restrictive enzymes and PCR amplification. Then, Large-scale preparation of pBK/SjB8 and pBK/SjGST were purified with PEG 8000, adjusted to 1¶Ãg /¶Ãl using normal saline as solvent, injected into BALB/c mice muscle. Three weeks later, the expressed results were observed using histochemistry technique. After that, BALB/c mice were vaccinated with single dosage of 100¶Ãg /mice using pBK/SjB8 and pBK/SjGST plasmid DNA, respectively. Two group mice and a normal group mice were challenged with 40 + 1 S. japonicum cercariae after 3 weeks vaccination. All mice were sacrificed at 6th week after challenge.
Results:The results demonstrated that ORF of SjB8 gene was subcloned into the plasmid pBK-CMV and the antigen and antibody reactions were seen in the mice muscular tissue. Compared with the control group, the worm reduction rates of pBK/SjB8 and pBK/SjGST plasmid DNA were 28.9% and 30.5%, respectively (P>0.05). Compared with the control group, the egg reduction rates of pBK/SjB8 and pBK/SjGST were 25.1% and 34.6%, (P<0.05) respectively.
Conclusions: a gene of new schistosome vaccine candidate
(SjB8) was cloned into pBK-CMV eukaryotic expression vector and
could express schistosome protein. The pBK/SjB8 recombinants were
used as DNA vaccine and showed its protective function.
Supported by National Nature Science Foundation of China(No.39570646)
and Nature Science Foundation of Anhui Province (No.00022031)
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created 21/12/00
