Abstract: Objective To observe the anti-schistosomiasis effect in mice immunized with Sjc97 DNA vaccine.Methods C57BL/6 mice were vaccinated intramuscularly with the Sjc97 DNA twice at an interval of 3 weeks， and challenged with 30±2 cercariae of Schistosoma japonicum three weeks after immunization. Mice in blank plasmid vector control and infection control groups were also infected with same number of cercariae. The mice were sacrificed 7 weeks after challenge infection. The size of single egg granulomas in livers was measured with micrometer. The level of hyaluronic acid （HA） and laminin （LN） in sera of the mice was determined by ELISA. PCR-ELISA was used to examine the expression of TGF-β1 mRNA in liver. Results The mean hepatic egg granuloma diameters of the three groups， the Sjc97 DNA， blank plasmid vector and infection control， were 183.75±42.36 microns， 303.12±37.36 microns and 304.38±53.23 microns， respectively. The hepatic granuloma was significantly smaller in the Sjc97 DNA group than that in control. The level of HA and LN in sera of Sjc97 DNA vaccinated mice was markedly lower than those in the two control groups（P<0.01）. The amount of TGF-β1 mRNA isolated from the livers of mice in Sjc97 DNA group decreased significantly. Conclusion The results showed that Sjc97 DNA vaccine may act as an effective inhibitor against formation of egg granuloma and reduce immunopathological damage caused by Schistosoma japonicum in the host.

Key words: Schistosoma japonicum, Paramyosin, Nucleic acid vaccine, Granuloma, Fibrosis, TGF-β1 mRNA