Johnson A J, Pessier A P, Jacobson E R
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.
Vet Pathol. 2007 May;44(3):285-97. doi: 10.1354/vp.44-3-285.
An experimental transmission study was designed to determine whether a causal relationship exists between a Ranavirus (BSTRV) isolated from a Burmese star tortoise that died and the lesions observed in that tortoise. A pilot study was performed with 3 box turtles (Terrapene ornata ornata) and 3 red-eared sliders (RESs; Trachemys scripta elegans) to assess their suitability in a larger study. Based on the outcome of this study, RESs were selected, and 2 groups of 4 RESs received either an oral (PO) or intramuscular (IM) inoculum containing10(5) 50% Tissue Culture Infecting Dose (TCID(50)) of a BSTRV-infected cell lysate. One turtle each was mock inoculated PO or IM with the same volume of uninfected cell lysate. Three of four IM-inoculated RESs developed clinical signs (nasal and ocular discharge [3 of 3], oral plaques [1 of 3], conjunctivitis and hyphema [1 of 3] and extreme lethargy [3 of 3]). A Ranavirus was isolated from kidney homogenates of 3 euthanatized turtles; DNA sequences of a portion of the major capsid protein gene were amplified by polymerase chain reaction. Consistent histologic lesions were observed only in IM-inoculated turtles and included fibrinoid vasculitis centered on splenic ellipsoids, multifocal hepatic necrosis, and multicentric fibrin thrombi in a variety of locations, including hepatic sinusoids, glomerular capillary loops, and pulmonary capillaries. Virions compatible with Ranavirus were observed within necrotic cells of the spleen of 1 IM-inoculated turtle using transmission electron microscopy. This study fulfills Koch's postulates, confirming a causal relationship between BSTRV and the clinical and histologic changes in chelonians infected with this virus.
设计了一项实验性传播研究，以确定从一只死亡的缅甸星龟分离出的一种蛙病毒（缅甸星龟蛙病毒，BSTRV）与在该龟身上观察到的病变之间是否存在因果关系。对3只锦龟（西部锦龟指名亚种，Terrapene ornata ornata）和3只红耳龟（红耳彩龟，Trachemys scripta elegans）进行了一项初步研究，以评估它们在更大规模研究中的适用性。根据这项研究的结果，选择了红耳龟，两组各4只红耳龟分别接受含有10(5) 50%组织培养感染剂量（TCID(50)）的BSTRV感染细胞裂解物的口服（PO）或肌肉注射（IM）接种物。各有一只龟分别用相同体积的未感染细胞裂解物进行假PO或IM接种。4只接受IM接种的红耳龟中有3只出现了临床症状（鼻和眼分泌物[3/3]、口腔斑块[1/3]、结膜炎和前房积血[1/3]以及极度嗜睡[3/3]）。从3只安乐死龟肾脏匀浆中分离出一种蛙病毒；通过聚合酶链反应扩增主要衣壳蛋白基因部分的DNA序列。仅在接受IM接种的龟中观察到一致的组织学病变，包括以脾椭球体为中心的纤维蛋白样血管炎、多灶性肝坏死以及在包括肝血窦、肾小球毛细血管袢和肺毛细血管在内的多个部位的多中心纤维蛋白血栓。使用透射电子显微镜在1只接受IM接种的龟脾脏坏死细胞内观察到与蛙病毒相符的病毒粒子。本研究满足了科赫法则，证实了BSTRV与感染该病毒的士鳖临床和组织学变化之间的因果关系。
