Cheng Kwang, Jones Megan E B, Jancovich James K, Burchell Jennifer, Schrenzel Mark D, Reavill Drury R, Imai Denise M, Urban Abby, Kirkendall Maryanne, Woods Leslie W, Chinchar V Gregory, Pessier Allan P
Department of Microbiology, University of Mississippi Medical Center, Jackson, MS 39216, USA.
Dis Aquat Organ. 2014 Sep 30;111(2):139-52. doi: 10.3354/dao02770.
A captive 'survival assurance' population of 56 endangered boreal toads Anaxyrus boreas boreas, housed within a cosmopolitan collection of amphibians originating from Southeast Asia and other locations, experienced high mortality (91%) in April to July 2010. Histological examination demonstrated lesions consistent with ranaviral disease, including multicentric necrosis of skin, kidney, liver, spleen, and hematopoietic tissue, vasculitis, and myriad basophilic intracytoplasmic inclusion bodies. Initial confirmation of ranavirus infection was made by Taqman real-time PCR analysis of a portion of the major capsid protein (MCP) gene and detection of iridovirus-like particles by transmission electron microscopy. Preliminary DNA sequence analysis of the MCP, DNA polymerase, and neurofilament protein (NFP) genes demonstrated highest identity with Bohle iridovirus (BIV). A virus, tentatively designated zoo ranavirus (ZRV), was subsequently isolated, and viral protein profiles, restriction fragment length polymorphism analysis, and next generation DNA sequencing were performed. Comparison of a concatenated set of 4 ZRV genes, for which BIV sequence data are available, with sequence data from representative ranaviruses confirmed that ZRV was most similar to BIV. This is the first report of a BIV-like agent outside of Australia. However, it is not clear whether ZRV is a novel North American variant of BIV or whether it was acquired by exposure to amphibians co-inhabiting the same facility and originating from different geographic locations. Lastly, several surviving toads remained PCR-positive 10 wk after the conclusion of the outbreak. This finding has implications for the management of amphibians destined for use in reintroduction programs, as their release may inadvertently lead to viral dissemination.
在一个来自东南亚和其他地区的两栖动物国际收集群体中，圈养着56只濒危的北方蟾蜍（Anaxyrus boreas boreas），它们组成了“生存保障”种群。在2010年4月至7月期间，该种群经历了高死亡率（91%）。组织学检查显示出与蛙病毒病相符的病变，包括皮肤、肾脏、肝脏、脾脏和造血组织的多中心坏死、血管炎以及无数嗜碱性胞质内包涵体。通过对主要衣壳蛋白（MCP）基因的一部分进行Taqman实时PCR分析以及通过透射电子显微镜检测虹彩病毒样颗粒，初步确认了蛙病毒感染。对MCP、DNA聚合酶和神经丝蛋白（NFP）基因的初步DNA序列分析显示与博勒虹彩病毒（BIV）具有最高的同源性。随后分离出一种暂定为动物园蛙病毒（ZRV）的病毒，并进行了病毒蛋白谱分析、限制性片段长度多态性分析和下一代DNA测序。将一组有BIV序列数据的4个ZRV基因与代表性蛙病毒的序列数据进行比较，证实ZRV与BIV最为相似。这是澳大利亚以外首次报道类似BIV的病原体。然而，尚不清楚ZRV是BIV的一种新型北美变体，还是通过接触共同生活在同一设施中且来自不同地理位置的两栖动物而获得的。最后，在疫情结束10周后，几只存活的蟾蜍PCR检测仍为阳性。这一发现对用于重新引入计划的两栖动物管理具有重要意义，因为它们的放归可能会无意中导致病毒传播。
