INGENASA (Inmunología y Genética Aplicada, SA), Madrid 28037, Spain.
ANSES, Animal Health Laboratory, Maisons-Alfort 94706, France.
Biomed Res Int. 2018 Sep 25;2018:8309816. doi: 10.1155/2018/8309816. eCollection 2018.
West Nile virus (WNV) is a zoonotic arboviral pathogen affecting humans, birds, and horses. Vaccines are available for veterinary use, which efficiently prevent the infection in horses. Most common diagnostic tools rely on the identification of the agent (RT-PCR, virus isolation), or on the detection of antibodies (IgM and IgG) recognizing structural proteins of the virus or neutralizing virus infection in cell cultures (virus-neutralization tests). The recent emergence of WNV in different parts of the world has resulted in an increase in the vaccination of horses in many countries. Methods for differentiation between infected and vaccinated animals ("DIVA" assays) would be useful for surveillance and control purposes but are still not available. A usual approach in this regard is the use of antibodies to nonstructural proteins as markers of nonvaccinated, infected animals, and the nonstructural NS1 protein of WNV has been proposed as a candidate for such a marker. The aim of this study was to test the hypothesis that NS1 can be a useful antigen in DIVA assays for differentiating WNV vaccinated and infected horses in field conditions. For that, we examined serum samples from either vaccinated and infected horses both from experimental infections/vaccinations (under controlled conditions) and from the field, exposed to natural infection or vaccinated in response to a risk of infection. The overall conclusion of the study is that NS1 antigen can effectively differentiate WNV infected from vaccinated horses in experimental (controlled) conditions, but this differentiation might be difficult depending on the conditions prevailing in the field.
西尼罗河病毒（WNV）是一种影响人类、鸟类和马的人畜共患虫媒病毒病原体。兽医用疫苗可有效预防马感染。最常见的诊断工具依赖于病原体的鉴定（RT-PCR、病毒分离），或识别病毒结构蛋白的抗体（IgM 和 IgG）或在细胞培养物中中和病毒感染的抗体（病毒中和试验）。WNV 在世界不同地区的最近出现导致许多国家增加了对马的疫苗接种。用于区分感染和接种动物的方法（“DIVA”检测）将有助于监测和控制目的，但仍不可用。在这方面的常用方法是使用非结构蛋白抗体作为未接种、感染动物的标志物，WNV 的非结构 NS1 蛋白已被提议作为此类标志物的候选物。本研究的目的是检验假设，即 NS1 可作为区分田间条件下接种和感染 WNV 的马的 DIVA 检测中的有用抗原。为此，我们检查了来自实验感染/接种（在受控条件下）和现场的接种和感染马的血清样本，这些马暴露于自然感染或因感染风险而接种。该研究的总体结论是，NS1 抗原可在实验（受控）条件下有效区分感染和接种的 WNV 马，但这种区分可能因现场的条件而异。
