Abstract: Objective To investig ate the development of different mucosal site immune responses induced by intransal immunization with CpG ODN plus Tox oplasma gondii soluble tachyzoite antigen(STAg)and the adjuvant effect of CpG ODN acting as complex mucosal vaccine adjuvant against Toxoplasma gondii.Methods Seventy-two 5-to-6 week-old female BA LB/c mice were divided into control group and infected group.The mice of infected group were immunized intranasally two times at 14-day intervals with 10Lg CpG ODN plus 20Lg STAg.The mice of control group were immunized intranasally with PBS at the same time.Six mice in each group were killed by dislocation of cervical vertebra on week 1,2,3,4,5,6 respectively after last immunity.IgA inrinse solution of nasopharynx,lung,intestinal,and vaginal were detected by ELISA.Results The average IgA level in each of the infected group was higher than that of the control group.IgA in nasopharynx wash samles was the highest on week 1 and it washigher than that of the control on each week but the difference was not significant.IgA inlung wash samples achieved the peak value on the 5th week and was higher than that of the control on week 4,5.6(P<0.001).IgA in intestine wash samples was higher than that of the control in each week and increased significantly on week 2,3(P<0.01)and the level was the highest on week 5.Conclusion Intranasal immunization with CpG ODN adjuvant and STAg can effectively induce persistent mucosal immune responses.