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用昆虫细胞中表达的弓形虫主要表面抗原(SAGI)为试剂检测弓形虫IgG抗体.方法将昆虫细胞中表达的重组蛋白(rSAGI)通过单克隆抗体制备的亲和层析柱纯化.用纯化的rSAGI为抗原试剂检测弓形虫病血清,与其他试剂盒检测结果比较,然后再用免疫印迹试验确认.结果重组杆状病毒Bac304感染的Sf9细胞与空载bacmid感染的细胞比较,Bac304的SDS裂解物比空载株在SDS?PAGE考马斯亮蓝染色胶上明显多出一条带,分子量约为30kDa.在恒定条件下,分批收集Bac304感染的昆虫细胞,用免疫荧光鉴定,95％以上的细胞可被感染.在Balb/C小鼠中生产的抗SAGI的单抗XllA10C与Bac304的表达产物发生反应,用纯化的单抗与CNBr?Sepharose4B偶联制备的亲和层析柱从1.3X109感染Bac304的昆虫细胞裂解液中获得1.4mgrSAGI,以纯化rSAGI为抗原,采用EIA法检测了412份妇产科就诊者及不明原因淋巴结肿大等病人血清,检出弓形虫lgG抗体阳性13例,其中10例经全虫体蛋白印迹法确认为阳性.结论昆虫细胞表达的重组SAG1能识别人弓形虫病血清,可以用作诊断试剂.“,”aim Toxoplasma major surface antigen(SAG1 ) expressed in Sf9 cells was use as a diagnostic reagent in EIA to detect IgG antibodies to Toxoplasma gondii. Methods The recombinant protein(rSAG1) was purified by immunoabsorption with anti--SAG1 mAb linked to CNBr--Sepharose 4B. EIA used rSAGI as an antigen was compared with other commercial EIA kits in detection of IgG antibody against T. gondii from patients'sera.. All positive results in any EIA tests were then confirmed by Western blot. Results The pattern of SDS--PAGE showed that the lysate of Sf9 cells infected with the recombinant baculovirus (Bac304) had one more band clearly seen in the gel stained with Coomasiae blue than that infected with bacmid,which has a molec-ular weight about 30KDa. In examination with immunofluorescent test,it was found that more than 95% of the cells harvested in batches could be infected with Bac304 under the condition of identical cultivation. The protein expressed in the infected cells could react with the ascites fluids XllA10C produced in Ballb/C mice. About 1. 4mg of the recombinant protein(rSAG1 ) was obtained by the immunoabsorption in which CNBr--Sepharose 4B was linked with the purified XllA10C. Four hundred twelve serum specimens collected from the outpatients of some maternal and child health care centers and patients with enlargement of lymphnodes with unknown reasons etc,were detected by EIA that used rSAGI as an antigen. In consequence, 13 specimens showed positive in anti-SAGI IgG antibody and 10 of which were confirmed by Western blot analysis. Conclusions The results suggest that the purified rSAGI can be recognized by human sera with the antibody to T. gondii, indicating that it can be used as a diagnostic reagent'