Abstract: 【Abstract】 Objective To study the protective immunity induced by recombinant vaccination of Cs-Rho GTPase of Clonorchis sinensis（Cs）． Methods 20 SD-rats（8 weeks） were divided into two groups： A（recombinant protein experiment group） and B （PBS control group）. Rats in group A were immunized with l ml protein of Cs-Rho GTPase （90 μg/ml） and 1 ml Freund′s complete adjuvant through back and vola. 2 week later， the rats were given 1 ml protein of Cs-Rho GTPase （90 μg/ml） and 1 ml Freund′s incomplete adjuvant, followed by 1 ml protein of Cs-Rho GTPase （90 μg/ml） through intraperitoneal injection at 4, 7, 11 week after the first immunization． Rats in group B were given PBS in the same way as group A． All rats were challenged each with 50 Clonorchis sinensis metacercariae after the last immunization． 21 d later， fecal samples were collected from all rats for examining eggs （number of eggs per gram feces, EPG） in every 3-5 d． When eggs were found， the rats were sacrificed and worms were collected. IgG、 IgG1 and IgG2a in sera were detected by ELISA before every immunization． Mean number of worms and eggs, and antibody level in the experiment group were calculated and statistically compared with the controls． Results The mean number of worms and EPG were （9.2±9.9） and （956.8±1 062.5） respectively in group A， which were significantly lower than those of group B ［（23.25±15.75） and （3 062.5±2 501.8） respectively］ （P<0.05）． The absorbency values of serum IgG （0.1, 0.45, 0.65, 0.6, 0.65）, IgG1 （0.1, 0.45, 1.1, 1.0, 1.1）, and IgG2a （0.1, 0.7, 1.1, 1.1, 1.1） before every immunization in group A were significantly higher than those of group B（almost always 0.1）（P<0.05）． Conclusion Recombinant vaccination of Cs-Rho GTPase induces partial protective immunity against Clonorchis sinensis infection in rats.

Key words: Clonorchis sinensis, Rho GTPase, Immunity