Camargo M E, da Silva S M, Leser P G, Granato C H
Laboratório Fleury de Análises Clínicas, São Paulo, Brasil.
Rev Inst Med Trop Sao Paulo. 1991 May-Jun;33(3):213-8.
For serologically characterizing a recent primary toxoplasma infection, the low avidity of IgG specific antibodies was studied. Avidity was evaluated as the decrease of IgG antibody titers in ELISA after treating plates with 6 M urea, as a dissociating solution of low avidity antigen-antibody complexes. Sixty nine serum samples were studied, presenting characteristic patterns of recent, transitional or chronic toxoplasmosis. Serological patterns were determined according to results of IgG and IgM immunofluorescence, IgM-capture, and hemagglutination tests. Twenty three serum samples from each of the referred patterns I, II and III were titrated. For chronic toxoplasmosis infections, which presented a serological pattern III, observed decrease of titers was 3% +/- 3%. For pattern I recent toxoplasmosis sera it was 34% +/- 12%, and for transition pattern II, 12% +/- 9%. Thus, a low avidity of IgG specific antibodies can be applicable for the diagnosis of a recent toxoplasmosis infection.
为了从血清学角度鉴定近期原发性弓形虫感染，研究了IgG特异性抗体的低亲和力。亲和力通过用6M尿素处理酶联免疫吸附测定（ELISA）板后IgG抗体滴度的降低来评估，6M尿素作为低亲和力抗原-抗体复合物的解离溶液。研究了69份血清样本，呈现近期、过渡性或慢性弓形虫病的特征模式。根据IgG和IgM免疫荧光、IgM捕获及血凝试验结果确定血清学模式。对上述模式I、II和III中的每组23份血清样本进行滴定。对于呈现血清学模式III的慢性弓形虫病感染，观察到的滴度降低为3%±3%。对于模式I近期弓形虫病血清，滴度降低为34%±12%，对于过渡模式II，滴度降低为12%±9%。因此，IgG特异性抗体的低亲和力可用于诊断近期弓形虫感染。
