PROTECTIVE IMMUNITY OF DNA VACCINE ENCODING SCHISTOSOMA JAPONICUM CHINESE STRAIN TRIOSE-PHOSPHATE ISOMERASE IN INFECTED BALB/c MICE

Objective To develop SjCTPI DNA vaccine for schistosomiasis japonica, and test the immune responses and the protective efficacy after immunization and challenge in BALB/c mice. Methods 39 of BALB/c mice were devided into three groups, group A (control group), each mice was injected with 100 μg of pcDNA3.1 by intramuscle, group B (experimental group) was injected with 100 μg of pcDNA3.1-SjCTPI, group C (strengthen group) was injected with 100 μg of pcDNA3.1-SjCTPI and 100 μg of mixture of pcDNA3.1-P35 and pcDNA3.1-P40. Eath mice was immunized three times at a two-week interval and challenged with 45 cercariae of Schistosoma japonicum Chinese strain four weeks post-immunization. Then the mice were sacrificed and perfused at 45 days after challenge, the numbers of recovered worms and hepatic eggs were counted. Cytotoxic activity mediated by SjCTPI was detected with the 51 Cr release assay. ELISA were performed for detection of anti-rTPI antibodies. Results The anti-rTPI antibody detection with ELISA showed that ten sera samples from the control group were negative, five of ten serum samples from group B were weak positive, six of ten from group C were weak positive too. The cytotoxic activity of the control group was 9.1%, while the cytotoxic activities of group B and group C were 27.6% and 54.4% respectively. The worm and egg reduction rates of group B and group C were 30.2 %, 52.9% and 32.7%, 47.0% respectively in comparison with the control group. Conclusion The results further proved the possibility of SjCTPI DNA vaccine as a potential DNA vaccine of schistosomiasis.