Centro de Investigación en Sanidad Animal, Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA-CISA), Valdeolmos, Spain.
Centro Militar de Veterinaria de la Defensa, Madrid, Spain.
Transbound Emerg Dis. 2019 Sep;66(5):2100-2106. doi: 10.1111/tbed.13262. Epub 2019 Jun 28.
This study aims at assessing the serological cross-reactions existing between three mosquito-borne flaviviruses with avian reservoirs co-circulating in Europe: West Nile (WNV), Usutu (USUV) and Bagaza (BAGV). The study is useful for a better interpretation of serological results in diagnostics and surveillance. Serum samples obtained from a natural host, the red-legged partridge (Alectoris rufa), experimentally infected with WNV, USUV or BAGV were analysed using two commercially available WNV competition ELISAs suitable for serological surveillance, and by the confirmatory virus neutralization test (VNT). The ELISAs examined showed different levels of specificity for WNV, as judged by cross-reaction observed with the other flaviviruses. By VNT, virus-specific antibodies were confirmed in 80%, 50% or 0% of sera from WNV-, BAGV-, or USUV-inoculated birds, respectively. The results indicate how the co-circulation of cross-reacting flaviviruses may affect the outcomes of WNV serological surveillance when applying currently available serological tools. On the one hand, the choice of the ELISA test for antibody screening should consider the differences found in specificity, since one test is more specific for WNV while the other one is more suitable for detection of a broader range of flavivirus antibodies. On the other hand, besides corroborating that cross-neutralization occurs between flaviviruses from different serocomplexes (WNV/USUV and BAGV), this study points out that cross-neutralization between WNV and USUV is not symmetric, and reveals the difficulty to identify USUV infections serologically. This finding indicates that actual USUV infections might be underestimated in the current diagnostic schemes.
本研究旨在评估三种在欧洲流行的具有鸟类宿主的蚊媒黄病毒（WNV、USUV 和 BAGV）之间存在的血清学交叉反应。该研究有助于更好地解释诊断和监测中的血清学结果。使用两种市售的适用于血清学监测的 WNV 竞争 ELISA 以及确认性病毒中和试验（VNT），对从实验感染 WNV、USUV 或 BAGV 的天然宿主红腿石鸡（Alectoris rufa）获得的血清样本进行分析。通过交叉反应观察到的交叉反应，所检查的 ELISA 显示出对 WNV 的不同特异性水平。通过 VNT，分别从接种 WNV、BAGV 或 USUV 的鸟类的血清中确认了 80%、50%或 0%的病毒特异性抗体。结果表明，当应用当前可用的血清学工具时，交叉反应的黄病毒的共同流行可能如何影响 WNV 血清学监测的结果。一方面，抗体筛选的 ELISA 测试的选择应考虑到特异性方面的差异，因为一种测试对 WNV 更具特异性，而另一种测试更适合检测更广泛范围的黄病毒抗体。另一方面，除了证实不同血清复合物（WNV/USUV 和 BAGV）之间存在交叉中和外，本研究还指出 WNV 和 USUV 之间的交叉中和不对称，并揭示了血清学识别 USUV 感染的困难。这一发现表明，在当前的诊断方案中，实际的 USUV 感染可能被低估。
