Abstract：
Felids are definitive hosts of Toxoplasma gondii, being the only hosts that can spread the infection through oocyst shedding in their feces. The elevated presence of this parasite in the domestic cat (Felis catus), and its close contact with humans, make it necessary to obtain reliable diagnostic methods to detect positive animals as a public health measure. For this reason, in this study, the diagnostic performance of five different recombinant antigen-based techniques was assessed to diagnose T. gondii infection in cat blood plasma samples. Specifically, four T. gondii recombinant antigens (GRA7, truncated GRA7, SAG2, and truncated SAG2) and a chimeric antigen (SAG1-GRA8) were used. A time-resolved fluorescence immunoassay (TRFIA) was developed for each antigen, and the results of each of these techniques were compared with those obtained by a commercial enzyme-linked immunoassay (ELISA) and a modified agglutination test (MAT) as reference techniques. The TRFIA based on SAG1-GRA8 antigen showed better discrimination between seropositive and seronegative cats (p < 0.001), as well as a better area under the curve (0.95), sensitivity (93.6%), and specificity (89.5%) values for the optimal cut-off, versus the other TRFIAs. In addition, SAG1-GRA8 TRFIA showed substantial agreement (kappa value = 0.78) and a moderate significant correlation (Spearman\'s correlation: r = 0.62, p < 0.001) compared with the reference techniques. On the other hand, since plasma samples were obtained from 101 cats in Bangkok city and four of them were Neospora caninum seropositive by indirect immunofluorescence assay (IFAT), this is the first time that anti-N. caninum antibodies are detected in cats in Thailand. In conclusion, our study highlights that the TRFIA with TgSAG1-GRA8 antigen is an accurate and recommended diagnostic technique for detecting anti-T. gondii antibodies in cats.
摘要：
Felids是弓形虫的确定宿主,是唯一可以通过卵囊在粪便中脱落来传播感染的宿主。这种寄生虫在家猫（Feliscatus）中的升高，以及它与人类的亲密接触，有必要获得可靠的诊断方法来检测阳性动物作为公共卫生措施。出于这个原因,在这项研究中，评估了5种不同的基于重组抗原的技术的诊断性能,以诊断猫血浆样本中的弓形虫感染.具体来说,使用四种弓形虫重组抗原(GRA7、截短的GRA7、SAG2和截短的SAG2)和嵌合抗原(SAG1-GRA8)。针对每种抗原开发了时间分辨荧光免疫测定（TRFIA），并将每种技术的结果与通过商业酶联免疫测定（ELISA）和改良的凝集测试（MAT）作为参考技术获得的结果进行了比较。基于SAG1-GRA8抗原的TRFIA在血清阳性和血清阴性猫之间显示出更好的区别（p<0.001），以及更好的曲线下面积（0.95），灵敏度（93.6%），和最佳截止值的特异性(89.5%)，与其他TRFIA相比。此外,与参考技术相比，SAG1-GRA8TRFIA显示出实质性的一致性（kappa值=0.78）和中等的显着相关性（Spearman\的相关性：r=0.62，p<0.001）。另一方面,由于血浆样本来自曼谷的101只猫，其中4只通过间接免疫荧光法（IFAT）检测为犬新孢子虫血清阳性，这是第一次反N。在泰国的猫中检测到犬抗体。总之,我们的研究强调，带有TgSAG1-GRA8抗原的TRFIA是检测抗T的准确和推荐的诊断技术。猫的刚地抗体。
