Institute of Parasitology, Vetsuisse-Faculty, University of Bern, Länggassstrasse 122, CH-3012 Bern, Switzerland.
Anses, INRAE, Ecole Nationale Vétérinaire d'Alfort, Laboratoire de Santé Animale, BIPAR, Maisons-Alfort F-94700, France.
Int J Parasitol. 2023 Aug;53(9):523-530. doi: 10.1016/j.ijpara.2022.11.003. Epub 2022 Dec 29.
Toxoplasma gondii is a major food-borne parasite and undercooked meat of infected pigs represents an important source of infection for humans. Since infections in pigs are mostly subclinical, adequate diagnostic tests for use at the farm level are pursued. Oral fluid (OF) was shown to be a promising matrix for direct and indirect detection of infections with various pathogens in pigs. The objective of this study was to assess whether T. gondii infections in pigs could be diagnosed using an indirect ELISA kit adapted for OF samples (OF-ELISA). Routine serology and OF-immunoblot (IB) were used as standards for the comparison. For this, serial OF samples from sows (n = 8) and fatteners (n = 3) experimentally inoculated with T. gondii oocysts, individual field samples from potentially exposed sows (n = 9) and pooled OF samples from potentially exposed group-housed fatteners (n = 195 pig groups, including 2,248 animals) were analysed for antibodies against T. gondii by ELISA. For individual animals, OF-ELISA exhibited a relative diagnostic specificity of 97.3% and a relative diagnostic sensitivity of 78.8%. In experimentally infected animals, positive OF-ELISA results were observed from 1.5 weeks post inoculation (pi) until the end of the experimental setup (8 to 30 weeks pi); however, values below the estimated cut-off were occasionally observed in some animals despite constant seropositivity. In potentially exposed individual animals, OF- and serum-ELISA results showed 100% agreement. In group-housed fatteners, antibodies against T. gondii could be reliably detected by OF-ELISA in groups in which at least 25% of the animals were seropositive. This OF-ELISA, based on a commercially available serum-ELISA, may represent an interesting non-invasive screening tool for detecting pig groups with a high exposure to T. gondii at the farm level. The OF-ELISA may need further adjustments to consistently detect individual infected pigs, probably due to variations in OF antibody concentration over time.
刚地弓形虫是一种重要的食源性寄生虫，未煮熟的感染猪肉代表了人类感染的重要来源。由于猪的感染大多是亚临床的，因此需要在农场层面上进行足够的诊断测试。口腔液（OF）已被证明是一种很有前途的基质，可以直接和间接检测猪体内各种病原体的感染。本研究的目的是评估是否可以使用适应 OF 样本的间接 ELISA 试剂盒（OF-ELISA）诊断猪的弓形虫感染。常规血清学和 OF 免疫印迹（IB）被用作比较的标准。为此，对经弓形虫卵囊实验接种的母猪（n=8）和育肥猪（n=3）的连续 OF 样本、可能暴露的母猪（n=9）的个体田间样本以及可能暴露的群养猪的 OF 混合样本（n=195 个猪群，包括 2248 只动物）进行了 ELISA 检测，以分析针对弓形虫的抗体。对于个体动物，OF-ELISA 的相对诊断特异性为 97.3%，相对诊断敏感性为 78.8%。在实验感染的动物中，从接种后 1.5 周（pi）开始到实验结束（8 至 30 周 pi）可以观察到 OF-ELISA 阳性结果；然而，尽管持续血清阳性，但一些动物的数值偶尔低于估计的截止值。在可能暴露的个体动物中，OF 和血清 ELISA 结果完全一致。在群养猪中，至少 25%的动物血清阳性的猪群中，可通过 OF-ELISA 可靠地检测到弓形虫抗体。该 OF-ELISA 基于市售的血清 ELISA，可能是一种在农场层面上检测高弓形虫暴露猪群的非侵入性筛选工具。由于 OF 抗体浓度随时间的变化，该 OF-ELISA 可能需要进一步调整，以始终如一地检测单个感染的猪。
