Abstract：To test immune protection of SjIR3 against challenge infection of Schistosoma japonicum(Sj) in mice.The special primers were designed according the sequence of SjIR3 in GeneBank (Ay25148). SjIR3 was amplified using Sj adult worm cDNA library as temple. The obtained sequence of SjIR3 was analyzed in internet. The recombinant plasmid pET-32(a) / SjIR3 was constructed by routine methods. The recombinant protein rSjIR3 was expressed by induced with IPIG. rSjIR3 was analyzed by SDS-PAGE and western-blot. Forty-four Kun-Ming mice (female, 20g) were randomly divided into 4 group each with per 11. Group A.B were control immunized with PBS and FCA respectively. Groups C,D were immunized with 50µg rSjIR3,50µg rSjIR3 + FCA respectively in 0-2-4-6th week. Levels specific antibody were detected by ELISA. The mice were challenged with 40±1 S.j cercariae per mouse 2 after the fourth vaccination. Forty-five days later, mice were killed and perfused, and the adult worms and eggs were counted. Results showed DNA segment of SjIR3 is 890 bp long and 100% identify with SjIR3 in GeneBank (AY251481). Protein expressed by SjIR3 is trans-membrane, the worm reduction rate was 26.63% and 34.79%. The egg reduction rate was 36.38% and 44.09%.
