Construction of the nucleic acid vaccine pcDNA3/SjCWL01 against Schistosoma japonicum and evaluation of its immuno-protective effect on mice

To evaluate the potential value of the novel gene of S. japonicum SjCWL01 as a nucleic acid candidate vaccine by the construction of pcDNA3/SjCWL01 followed by observation of its immunological protection effect on mice. A novel gene of S. japonicum SjCWL01 was subcloned into the eukaryotic expression vector pcDNA3. The positive recombinants were identified by PCR and restriction enzyme digestion. Preparation of the DNA vaccine was made by transforming the plasmid pcDNA3/SjCWL01 into E.coli DH5α. The experimental mice were immunized with purified pcDNA3/SjCWL01 DNA vaccine and challenged with 40±1 S. japonicum cercariae percutaneously at the 2nd week after the third immunization. Levels of the specific antibody were detected by ELISA before infection. The reduction rates of the worm burden, liver eggs per gram and fecal eggs per gram were examined 45 days after challenge infection. Compared with the control group, the reduction rates of the worm burden, liver eggs per gram and fecal eggs per gram were 27.6%, 39.5% and 45.9% in the experimental mice, respectively. The pcDNA3/SjCWL01 nucleic acid vaccine can induce partial protective immunity against S. japonicum infection in mice.