Department of Veterinary Science, Gluck Equine Research Center, University of Kentucky, Lexington KY, USA.
Vet Rec. 2013 Feb 23;172(8):210. doi: 10.1136/vr-2012-100735. Epub 2012 Nov 16.
Serological diagnosis of equine infectious anaemia virus (EIAV) infections has depended mainly on the agar gel immunodiffusion test (AGIDT). This study documents the presence of EIAV genetic sequences in a number of persistently infected horses and mules whose serums were interpreted as negative/equivocal on AGIDT, but positive on more than one ELISA test and in immunoblot tests. Strategies designed to take advantage of the combined strengths of the ELISA and AGIDT are shown effective in a national surveillance program for EIA in Italy where 17 per cent (25/149) of the equids considered to be infected with EIAV on combined/comparative serological data had reactions in the AGIDT that were interpreted as negative or equivocal. These data document the benefits of using a three-tiered laboratory system for the diagnosis of EIA. Although the ELISA-first strategy introduces some confusing results, the discovery of up to 20 per cent more cases of EIA makes it compelling. In our opinion, it is better and more defensible to find two samples in 1000 with resolvable but falsely positive ELISA tests for EIA than to release two to three horses in 10,000 with falsely negative test results for EIA (the rates seen in the Italian surveillance presented here).
马传染性贫血病毒(EIAV)感染的血清学诊断主要依赖于琼脂凝胶免疫扩散试验(AGIDT)。本研究记录了一些持续性感染马和骡子的 EIAV 遗传序列的存在,其血清在 AGIDT 上被解释为阴性/可疑,但在多个 ELISA 检测和免疫印迹检测中呈阳性。在意大利的 EIA 国家监测计划中,利用 ELISA 和 AGIDT 的联合优势的策略被证明是有效的,在该计划中,根据联合/比较血清学数据,17%(25/149)被认为感染了 EIAV 的马在 AGIDT 中出现了被解释为阴性或可疑的反应。这些数据记录了使用三层实验室系统诊断 EIA 的好处。尽管 ELISA 优先策略会引入一些混淆的结果,但发现多达 20%的更多 EIA 病例使其变得引人注目。在我们看来,发现 1000 个样本中有两个样本的 ELISA 检测结果存在可解决但假阳性的情况,比在 10000 个样本中发现两个到三个 EIA 检测结果假阴性的情况要好得多,也更有说服力(这里呈现的意大利监测数据中就存在这种情况)。