[Protective effect induced by vaccination with a partial cDNA expression library of Schistosoma japonicum in mice]

The cDNA fragments of interest were amplified using Sj lambda ZipLox library as the templates by PCR and then cloned into a eukaryotic expression vector p-CMV-GH; A small number of DNA fragments inserted in the recombinants was identified by restriction cleavage, EST sequencing and bioinformatical analysis; mice were injected intramuscularly with the expression library (L-CMV-SjR) or sublibraries(L-CMV-SjR1, L-CMV-SjR2 and L-CMV-SjR3), immunized mice were challenged with Schistosoma japonicum cercariae on day 35, the levels of IgG antibodies in sera from the immunized mice were detected by ELISA. The results demonstrated that a partial cDNA expression library of S.j, with approximately 10(5) transformants, was constructed, most of the recombinants contained the insert DNA fragments of interest, and these fragments had the features of protein-coding sequences for Schistosome. There were no significant differences for the levels of IgG antibodies in sera from all of the immunized groups. Mice immunized with L-CMV-SjR, L-CMV-SjR1 and L-CMV-SjR2 developed significant protective effect against Sj infection compared to control mice injected with the empty plasmid, the rate of worm reduction was about 30%.