Abstract: Tetraspanin 2-A （SjTsp2-A） gene was amplified by PCR. pcDNA3.1（+）/SjTsp2-A recombinant plasmids were constructed and transformed into E. coli DH5α. Twenty four BALB/c mice were randomly divided into pcDNA3.1（+）/SjTsp2-A group （A）, pcDNA3.1（+）/SjGST group （B） and pcDNA3.1（+） group （C）. Each mouse was injected through musculus quadriceps femoris by three times （two weeks interval） respectively with 100 μg pcDNA3.1（+）/SjTsp2-A, pcDNA3.1（+）/SjGST, or pcDNA3.1（+）. At two weeks after the final inoculation, mice were each challenged by 40±2 cercariae of S. japonicum. Forty-five days after infection， all mice were sacrificed, the number of worms collected and eggs in liver tisssue was counted. Anti-pcDNA3.1（+）/SjTsp2-A antibody was detected by ELISA and protein expression in quadriceps muscle by immunohistochemical staining. The worm reduction rate （44.4%） and egg reduction rate （28.4%） of group A was higher than those of group B and C （P＜0.05）, but no significant difference between groups B （3.9%, 19.3%） and C. Higher antibody titer （1 ∶ 25 600） was detected in sera of group A. Immunohistochemistry analysis showed an expression of specific antigens in quadriceps muscles of groups A and B. The DNA candidate vaccine induces partial protective immunity against S. japonicum in BALB/c mice.

Key words: Schistosoma japonicum, Surface membrane protein, DNA vaccine, Protective immunity