Legnardi Matteo, Franzo Giovanni, Tucciarone Claudia Maria, Koutoulis Konstantinos, Cecchinato Mattia
Department of Animal Medicine, Production and Health, University of Padova, Legnaro (PD), Italy.
Department of Poultry Diseases, Faculty of Veterinary Science, University of Thessaly, Karditsa, Greece.
Avian Pathol. 2023 Feb;52(1):25-35. doi: 10.1080/03079457.2022.2130172. Epub 2022 Oct 26.
Infectious bursal disease virus (IBDV) is a highly contagious birnavirus causing a burdensome immunosuppressive disease in chickens. IBDV features a remarkable antigenic, pathogenic and genetic heterogeneity, with significant implications on disease manifestation, control measures and diagnostic approaches. The recent proposals of comprehensive phylogenetic classification systems offered the ideal platform for large-scale molecular surveys, which are crucial to gather epidemiological data and inform control efforts. In this study, the IBDV scenario was investigated in most of Western Europe by considering the results of diagnostic activities performed internationally throughout 2021. In total, 470 bursal samples from nine different countries were analysed by RT-PCR targeting the VP2. When a field virus was identified, the VP1 was also characterized. Most of the 132 detected field viruses were highly homologous reassortants featuring a very virulent-like VP2 and a classical-like VP1 (genotype A3B1). Despite emerging recently, these reassortants were already signalled in several countries in North-Western Europe and associated with subclinical infections. Here, we report their further spread in the region, where they currently represent the dominant field threat. Two other IBDV types were found, one in Italy, where all the identified viruses clustered in a clade of the A3B1 genotype previously reported only in Russia and the Middle East, and the other in Portugal, where the recently characterized A9B1 genotype was confirmed to circulate. The obtained data suggest the recent occurrence of a major shift in the Western European epidemiological landscape of IBDV, stressing the importance of steady monitoring and sharing of information among different countries and laboratories. The IBDV scenario in Western Europe seems to have radically changed in recent years.IBDV reassortants were found to be the dominant field type in the region.Local circulation of two other IBDV types was detected in Italy and Portugal.
传染性法氏囊病病毒（IBDV）是一种高度传染性的双RNA病毒，可在鸡群中引发严重的免疫抑制性疾病。IBDV具有显著的抗原性、致病性和遗传异质性，这对疾病表现、防控措施及诊断方法都具有重要影响。近期提出的全面系统发育分类体系为大规模分子调查提供了理想平台，而大规模分子调查对于收集流行病学数据及指导防控工作至关重要。在本研究中，通过考量2021年全年在国际上开展的诊断活动结果，对西欧大部分地区的IBDV情况进行了调查。总共对来自9个不同国家的470份法氏囊样本进行了针对VP2的逆转录聚合酶链反应（RT-PCR）分析。当检测到野外病毒时，还对VP1进行了特征分析。所检测到的132种野外病毒中，大多数是高度同源的重配体，其VP2具有很强的致病性，VP1具有典型特征（A3B1基因型）。尽管这些重配体最近才出现，但在西北欧的几个国家已被发现，并与亚临床感染有关。在此，我们报告了它们在该地区的进一步传播情况，目前它们是该地区主要的野外威胁。还发现了另外两种IBDV类型，一种在意大利，所有鉴定出的病毒都聚集在一个先前仅在俄罗斯和中东报道过的A3B1基因型分支中；另一种在葡萄牙，新近鉴定的A9B1基因型被证实正在传播。所获数据表明，西欧IBDV的流行病学格局近期发生了重大变化，凸显了不同国家和实验室之间持续监测和信息共享的重要性。近年来，西欧的IBDV情况似乎发生了根本性变化。IBDV重配体被发现是该地区主要的野外类型。在意大利和葡萄牙检测到另外两种IBDV类型的本地传播。
