Experimental transmission and induction of ranaviral disease in Western Ornate box turtles (Terrapene ornata ornata) and red-eared sliders (Trachemys scripta elegans).
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.
Johnson
A J
AJ
Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL 32610, USA.
Pessier
A P
AP
Jacobson
E R
ER
D000820:Animal Diseases / Q000473:pathology / Q000635:transmission* / Q000821:virology*; D000818:Animals; D003106:Colon / Q000473:pathology; D004266:DNA Virus Infections / Q000473:pathology / Q000635:transmission / Q000662:veterinary*; D006257:Head / Q000473:pathology; D008099:Liver / Q000473:pathology; D009061:Mouth Mucosa / Q000473:pathology; D017995:Ranavirus / Q000502:physiology*; D013154:Spleen / Q000473:pathology; D014426:Turtles / Q000821:virology*