Pezzoni Giulia, Caminiti Antonino, Stercoli Lidia, Grazioli Santina, Galletti Giorgio, Santi Annalisa, Tamba Marco, Brocchi Emiliana
Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia-Romagna, Via Bianchi 9, 25124 Brescia, Italy.
J Virol Methods. 2014 Oct;207:95-103. doi: 10.1016/j.jviromet.2014.06.025. Epub 2014 Jul 7.
Hepatitis E virus (HEV) is a RNA non-enveloped virus that comprises four genotypes. The genome of HEV is organized into three Open Reading Frames (ORFs), and the ORF2 is responsible for encoding capsid proteins. HEV can infect a wide range of hosts, and pigs are considered the main reservoir. HEV infection is considered a zoonosis and it is responsible for acute hepatitis in humans, especially in developing countries. The development of a blocking ELISA would be of high value for screening purpose, because there is no need of species specific reagents. The present study was conducted to assess three in-house ELISAs for the detection of HEV infection in 779 sera collected from breeding and fattening farms under field conditions. Two assays were indirect ELISAs, while the third was a blocking ELISA. Two different recombinant antigens were generated from specific sequences of the HEV-ORF2, and a Latent Class approach in a Bayesian framework was used to evaluate the diagnostic accuracy of each ELISA. Because the three ELISAs cannot be thought of as independent, all possible dependence structures were modelled starting from the general case of conditional independence to the most complex situation of three mutually dependent assays. Results showed that none of the three ELISAs was significantly superior to the others in terms of sensitivity (posterior median value ranging from 89% to 94%, all 95% posterior credible intervals (95%PCI) overlapped). In terms of specificity, one of the indirect ELISAs was superior to blocking ELISA (posterior median indirect ELISA: 99%, 95%PCI: 98-100%; blocking ELISA: 90%; 95%PCI: 86-94%). However, this difference could be due to the potential wider spectrum of antibodies that blocking ELISA can actually detect.
戊型肝炎病毒（HEV）是一种RNA无包膜病毒，包括四种基因型。HEV基因组由三个开放阅读框（ORF）组成，其中ORF2负责编码衣壳蛋白。HEV可感染多种宿主，猪被认为是主要储存宿主。HEV感染被视为一种人畜共患病，它是导致人类急性肝炎的原因，尤其是在发展中国家。开发一种阻断ELISA用于筛查具有很高的价值，因为不需要种属特异性试剂。本研究旨在评估三种自制ELISA，以检测在田间条件下从繁殖场和育肥场采集的779份血清中的HEV感染情况。两种检测方法是间接ELISA，而第三种是阻断ELISA。从HEV-ORF2的特定序列产生了两种不同的重组抗原，并采用贝叶斯框架下的潜在类别方法来评估每种ELISA的诊断准确性。由于这三种ELISA不能被视为相互独立，所有可能的依赖结构都从条件独立的一般情况到三种相互依赖检测的最复杂情况进行建模。结果表明，在敏感性方面，三种ELISA均无显著优于其他方法（后验中位数范围为89%至94%，所有95%后验可信区间（95%PCI）重叠）。在特异性方面，一种间接ELISA优于阻断ELISA（间接ELISA后验中位数：99%，95%PCI：98 - 100%；阻断ELISA：90%；95%PCI：86 - 94%）。然而，这种差异可能是由于阻断ELISA实际能检测的抗体谱可能更宽。
