PROTECTIVE EFFECTS OF DNA-PLASMID VACCINE OF SCHISTOSOMA JAPONICUM CHINESE STRAIN TRIOSE-PHOSPHATE ISOMERASE IN INFECTED PIGS

Objective To induce protective effects immunized with DNA-plasmid vaccine of Schistosoma japonicum Chinese strain triose-phosplate isomerase in infected pigs. Methods Construction and preparation of pcDNA3.1-SjCTPI DNA vaccine and pcDNA3 1-P35, pcDNA3 1-P40 (two subunits of IL-12) DNA vaccines were performed. Thirty Chinese Songjang native pigs which were castrated were divided into A,B and C three groups. In group A (TPI group), each pig was immunized with 500μg of SjCTPI plasmid DNA by intramuscle (i.m.) in both buttocks. In group B (TPI+IL-12 group), each pig was immunized with 500μg of SjCTPI plasmid DNA and 500 μg of pcDNA3 1-P35 DNA, pcDNA3 1-P40 DNA by i m. In group C, each pig was immunized (i.m.)with 500 μg of pcDNA3 1 as control. All pigs in the three groups were immunized for three times with three weeks interval. At day 30 after last immunization, each pig was challenged with 600 of cercariae of Schistosoma japonicum on the back of pigs. At day 45, the pigs were sacrificed and perfused. The recovered adult worms were counted. Small piece of each pig's liver was cut and dis-solved in 5% of KOH, and the eggs were counted. The worm reduction rate, female worm reduction rate and eggs per gram liver tissue reduction rate between groups were compared. The sera be- fore immunization, after last immunization and after challenge were collected from pig 's ear vein. The anti-SjCTPI antibody was detected with ELISA. Results In TPI group and TPI+IL-12 group, the worm reduction rates were 48 3% and 46 2% compared with that in control group respectively, the female worm reduction rates were 53 6% and 59 6%, the egg reduction rates were 49 4% and 65 8% respectively. In 6 of 10 pigs of TPI group anti-SjCTPI antibody could be detected, and in TPI+IL-12 group, in 5 of 10 pigs anti-SjCTPI antibody could be detected. Conclusion SjCTPI plasmid DNA vaccine could induce higher protective immunity effects in infectd pigs. It indicated that SjCTPI DNA vaccine is a good potential anti-schistosomiasis vaccine.