Protective immunity effect of Schistosoma japonicum multivalent DNA vaccine in infected BALB/c mice / 中国血吸虫病防治杂志

ABSTRACT

Objective To test the protective effect of multivalent DNA vaccine against Schistosoma japonicum infection. Methods Sixty-five female BALB/c mice of 5-6 weeks old were randomly divided into 5 groups pcDNA3.1 group (control group), pcDNA3.1-TPI group (TPI), pcDNA3.1-(CDR3)_6 group [(CDR3)_6], pcDNA3.1-TPI-linker-(CDR3)_6 group (TLC) and pcDNA3.1-(CDR3)_6-linker-TPI group (CLT). Each mouse was immunized with 100 ?g of pcDNA3.1 , pcDNA3.1-TPI,pcDNA3.1-(CDR3)_6 ,pcDNA3.1-TPI-linker-(CDR3)_6 or pcDNA3.1-(CDR3)_6-linker-TPI plasmid DNA by intramuscular injection, respectively. All animals were boosted at week 2 and week 4 with the same dosage and same method. Four weeks after the 3rd immunization, all mice were challenged with (45?1) cercariae of Schistosoma japonicum by abdominal skin penetration. Forty-five days post-challenge, the mice were sacrificed and perfused, and the numbers of recoveredworms and hepatic eggs were counted. The blood was collected from the tail veins of all mice 2 days before the 1st immunization and challenge, respectively. Serum was prepared for detection of IgG, IgG_1 and IgG_ 2a . Two weeks after the 3rd immunization, the spleen cells of 2 mice from each group were cultured and stimulated with ConA and rSjCTPI peptide, and the supernatant was collected for detection of IL-2, IL-4 and IFN-?. Results The worm reduction rates in TPI group, (CDR3)_6 group, TLC group and CLT group were 26.25%, 24.10%, 37.30% and 39.09%, the hepatic egg reduction rates were 32.64%, 32.27%, 41.61% and 49.54% respectively compared with the control group. The levels of protection in TLC group and CLT group both were higher than those in TPI group and (CDR3)_6 group(P