Costa Juan G, Peretti Leandro E, García Valeria S, Peverengo Luz, González Verónica D G, Gugliotta Luis M, Dalla Fontana Maria L, Lagier Claudia M, Marcipar Iván S
Clin Chem Lab Med. 2017 Mar 1;55(4):595-604. doi: 10.1515/cclm-2016-0331.
P35 and P22 Toxoplasma gondii proteins are recognized by specific IgG at the early infection stage, making them ideal for acute toxoplasmosis pregnancy control. Both proteins have been studied to discriminate between acute and chronic toxoplasmosis. However, results were hardly comparable because different protein obtainment procedures led to different antigens, the reference panels used were not optimally typified, and avidity tests were either not performed or narrowly examined.
We bioinformatically predicted P35 and P22 regions with the highest density of epitopes, and expressed them in pET32/BL21DE3 alternative expression system, obtaining the soluble proteins rP35a and rP22a. We assessed their diagnostic performance using pregnant woman serum samples typified as: not infected, NI (IgG-, IgM-), typical-chronic, TC (IgM-, IgG+), presumably acute, A (IgG+, IgM+, low-avidity IgG), and recently chronic, RC (IgG+, IgM+, high-avidity IgG).
rP35a performed better than rP22a to differentiate A from RC, the areas under the curve (AUC) being 0.911 and 0.818, respectively. They, however, performed similarly to differentiate A from TC+RC (AUC: 0.915 and 0.907, respectively). rP35a and rP22a evaluation by avidity ELISA to discriminate A from RC rendered AUC values of 0.974 and 0.921, respectively. The indirect ELISA and avidity ELISA results analyzed in tandem were consistent with those obtained using commercial kits.
rP35a and rP22a features suggest that, with complementary use, they could replace parasite lysate for toxoplasmosis infection screening and for acute toxoplasmosis diagnosis. Our proposal should be validated by a longitudinal study and may lead to a reliable toxoplasmosis pregnancy control, performing tests in only one serum sample.
刚地弓形虫的P35和P22蛋白在感染早期可被特异性IgG识别，使其成为孕期急性弓形虫病控制的理想选择。这两种蛋白均已用于鉴别急性和慢性弓形虫病。然而，由于不同的蛋白获取程序导致抗原不同、所使用的参考样本未得到最佳分型，且未进行亲和力测试或测试范围狭窄，因此结果难以比较。
我们通过生物信息学方法预测了P35和P22中表位密度最高的区域，并在pET32/BL21DE3替代表达系统中进行表达，获得可溶性蛋白rP35a和rP22a。我们使用以下分型的孕妇血清样本评估它们的诊断性能：未感染（NI，IgG-，IgM-）、典型慢性感染（TC，IgM-，IgG+）、疑似急性感染（A，IgG+，IgM+，低亲和力IgG）和近期慢性感染（RC，IgG+，IgM+，高亲和力IgG）。
在区分A和RC方面，rP35a的表现优于rP22a，曲线下面积（AUC）分别为0.911和0.818。然而，在区分A和TC+RC方面，它们的表现相似（AUC分别为0.915和0.907）。通过亲和力ELISA评估rP35a和rP22a以区分A和RC，AUC值分别为0.974和0.921。串联分析的间接ELISA和亲和力ELISA结果与使用商业试剂盒获得的结果一致。
rP35a和rP22a的特性表明，联合使用时，它们可替代寄生虫裂解物用于弓形虫病感染筛查和急性弓形虫病诊断。我们的提议应通过纵向研究进行验证，并且可能实现可靠的孕期弓形虫病控制，仅需检测一份血清样本。
