Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Espinardo, 30100 Murcia, Spain.
Interdisciplinary Laboratory of Clinical Analysis, Interlab-UMU, University of Murcia, Regional Campus of International Excellence "Campus Mare Nostrum", Espinardo, 30100 Murcia, Spain.
Vet Parasitol. 2022 Apr;304:109703. doi: 10.1016/j.vetpar.2022.109703. Epub 2022 Mar 28.
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.
猫科动物是刚地弓形虫的明确宿主，是唯一能够通过粪便中的卵囊脱落传播感染的宿主。这种寄生虫在家猫（Felis catus）中的高存在率，以及它与人类的密切接触，使得有必要获得可靠的诊断方法来检测阳性动物，作为一项公共卫生措施。出于这个原因，在这项研究中，评估了五种不同的基于重组抗原的技术的诊断性能，以检测猫血浆样本中的刚地弓形虫感染。具体来说，使用了四种刚地弓形虫重组抗原（GRA7、截短 GRA7、SAG2 和截短 SAG2）和一种嵌合抗原（SAG1-GRA8）。为每个抗原开发了时间分辨荧光免疫分析（TRFIA），并将这些技术中的每一种的结果与商业酶联免疫吸附测定（ELISA）和改良凝集试验（MAT）的结果进行比较，作为参考技术。基于 SAG1-GRA8 抗原的 TRFIA 显示出更好的区分血清阳性和血清阴性猫的能力（p<0.001），以及更好的曲线下面积（0.95）、敏感性（93.6%）和特异性（89.5%）值，用于最佳截断值，与其他 TRFIAs 相比。此外，SAG1-GRA8 TRFIA 与参考技术相比，具有实质性一致性（kappa 值=0.78）和中度显著相关性（Spearman 相关性：r=0.62，p<0.001）。另一方面，由于从曼谷市的 101 只猫中获得了血浆样本，其中 4 只通过间接免疫荧光测定（IFAT）呈新孢子虫阳性，这是首次在泰国猫中检测到抗新孢子虫抗体。总之，我们的研究表明，TgSAG1-GRA8 抗原的 TRFIA 是一种准确且推荐的诊断技术，可用于检测猫中的抗刚地弓形虫抗体。
