Centre for Biological Threats and Special Pathogens 1 (ZBS1) - Highly Pathogenic Viruses, Robert Koch-Institut, Nordufer, Berlin, Germany.
PLoS Negl Trop Dis. 2013 Apr 25;7(4):e2184. doi: 10.1371/journal.pntd.0002184. Print 2013.
In recent decades, sporadic cases and outbreaks in humans of West Nile virus (WNV) infection have increased. Serological diagnosis of WNV infection can be performed by enzyme-linked immunosorbent assay (ELISA), immunofluorescence assay (IFA) neutralization test (NT) and by hemagglutination-inhibition assay. The aim of this study is to collect updated information regarding the performance accuracy of WNV serological diagnostics.
METHODOLOGY/PRINCIPAL FINDINGS: In 2011, the European Network for the Diagnostics of Imported Viral Diseases-Collaborative Laboratory Response Network (ENIVD-CLRN) organized the second external quality assurance (EQA) study for the serological diagnosis of WNV infection. A serum panel of 13 samples (included sera reactive against WNV, plus specificity and negative controls) was sent to 48 laboratories involved in WNV diagnostics. Forty-seven of 48 laboratories from 30 countries participated in the study. Eight laboratories achieved 100% of concurrent and correct results. The main obstacle in other laboratories to achieving similar performances was the cross-reactivity of antibodies amongst heterologous flaviviruses. No differences were observed in performances of in-house and commercial test used by the laboratories. IFA was significantly more specific compared to ELISA in detecting IgG antibodies. The overall analytical sensitivity and specificity of diagnostic tests for IgM detection were 50% and 95%, respectively. In comparison, the overall sensitivity and specificity of diagnostic tests for IgG detection were 86% and 69%, respectively.
CONCLUSIONS/SIGNIFICANCE: This EQA study demonstrates that there is still need to improve serological tests for WNV diagnosis. The low sensitivity of IgM detection suggests that there is a risk of overlooking WNV acute infections, whereas the low specificity for IgG detection demonstrates a high level of cross-reactivity with heterologous flaviviruses.
近几十年来，人类感染西尼罗河病毒（WNV）的散发病例和暴发有所增加。WNV 感染的血清学诊断可通过酶联免疫吸附试验（ELISA）、免疫荧光试验（IFA）、中和试验（NT）和血凝抑制试验（HAI）进行。本研究旨在收集有关 WNV 血清学诊断准确性的最新信息。
方法/主要发现：2011 年，欧洲进口病毒病诊断网络-合作实验室反应网络（ENIVD-CLRN）组织了第二次西尼罗河病毒血清学诊断的外部质量保证（EQA）研究。向参与 WNV 诊断的 48 个实验室发送了包含 13 个样本的血清面板（包括对 WNV 有反应的血清，以及特异性和阴性对照）。来自 30 个国家的 47 个/48 个实验室参加了该研究。有 8 个实验室获得了 100%的同步和正确结果。其他实验室在获得类似结果方面的主要障碍是异源黄病毒抗体的交叉反应性。实验室使用的内部和商业测试在性能上没有差异。IFA 检测 IgG 抗体的特异性明显高于 ELISA。用于 IgM 检测的诊断测试的总体分析灵敏度和特异性分别为 50%和 95%。相比之下，用于 IgG 检测的诊断测试的总体灵敏度和特异性分别为 86%和 69%。
结论/意义：这项 EQA 研究表明，WNV 诊断的血清学检测仍需改进。IgM 检测的低灵敏度表明，WNV 急性感染可能被忽视，而 IgG 检测的低特异性表明与异源黄病毒的交叉反应性很高。
