Aguado-Martínez A, Alvarez-García G, Fernández-García A, Risco-Castillo V, Arnaiz-Seco I, Rebordosa-Trigueros X, Navarro-Lozano V, Ortega-Mora L M
SALUVET, Animal Health Department, Complutense University of Madrid, Ciudad Universitaria s/n, 28040-Madrid, Spain.
Vet Parasitol. 2008 Nov 7;157(3-4):182-95. doi: 10.1016/j.vetpar.2008.08.002. Epub 2008 Aug 13.
Bovine reproductive failure caused by the parasite Neospora caninum is a major problem and is responsible for severe economic losses worldwide. Currently, appropriate control measures depend on the predominant transmission route in a particular herd. Therefore, the development of diagnostic tools capable of discriminating between primo-infection, recrudescence, re-infection, and chronic infection is a major challenge in the serodiagnosis of bovine neosporosis. Here, two recombinant protein-based ELISAs utilizing the immunodominant NcGRA7 dense granule protein and the NcSAG4 bradyzoite stage-specific protein were developed and showed good diagnostic performances. Their usefulness for discerning between primo-infection, recrudescence, re-infection, and chronic infection was also studied by analyzing an appropriate panel of serum samples belonging to different groups of experimentally and naturally infected bovines. Our results suggest that anti-rNcGRA7 antibody levels may be indicative of acute infection (primo-infection, re-infection, and recrudescence), whereas the presence of anti-rNcSAG4 antibodies may be associated with chronic infection and could be a good indicator of infection establishment (tachyzoite-bradyzoite conversion). Moreover, primo-infection associated with a Neospora-associated epidemic abortion pattern is characterized by the detection of anti-rNcGRA7 antibodies together with the absence or detection of anti-rNcSAG4 antibody levels around the cut-off point. In contrast, the detection of antibody levels directed against both recombinant proteins may be quite indicative of recrudescence or re-infection associated with abortion and/or vertical transmission in herds with a Neospora-associated endemic abortion pattern. In conclusion, both serological tests developed in the present study offer additional information to conventional avidity tests and, consequently, improve the diagnosis of bovine neosporosis with perspectives for control measures.
由犬新孢子虫寄生虫引起的牛繁殖失败是一个主要问题，在全球范围内造成严重的经济损失。目前，适当的控制措施取决于特定牛群中的主要传播途径。因此，开发能够区分初次感染、复发感染、再次感染和慢性感染的诊断工具是牛新孢子虫病血清诊断中的一项重大挑战。在此，开发了两种基于重组蛋白的酶联免疫吸附测定（ELISA），它们利用免疫显性的NcGRA7致密颗粒蛋白和NcSAG4缓殖子阶段特异性蛋白，并且显示出良好的诊断性能。通过分析属于不同组的实验性和自然感染牛的合适血清样本面板，还研究了它们在区分初次感染、复发感染、再次感染和慢性感染方面的有用性。我们的结果表明，抗rNcGRA7抗体水平可能指示急性感染（初次感染、再次感染和复发感染），而抗rNcSAG4抗体的存在可能与慢性感染相关，并且可能是感染确立（速殖子-缓殖子转化）的良好指标。此外，与新孢子虫相关的流行性流产模式相关的初次感染的特征是检测到抗rNcGRA7抗体，同时抗rNcSAG4抗体水平在临界值附近不存在或检测到。相比之下，针对两种重组蛋白的抗体水平的检测可能相当指示与新孢子虫相关的地方性流产模式的牛群中与流产和/或垂直传播相关的复发感染或再次感染。总之，本研究中开发的两种血清学检测方法为传统的亲和力检测提供了额外信息，并因此改善了牛新孢子虫病的诊断，为控制措施提供了前景。
