28th Annual Meeting and Symposium of the
Desert Tortoise Council, February 21-23, 2003
Abstracts

STUDENT PAPER

Herpesvirus Infection in a Captive Desert Tortoise (Gopherus agassizii)

April J. Johnson¹, E. R. Jacobson¹, F. C. Origgi², R. Brown^3
1Department of Small Animal Clinical Sciences, University of Florida, Gainesville, Florida 32610
²Human Virology Unit, Department of Infectious Diseases and Immunology, San Raffaele Scientific Institute (Dibit), Milano, Italy
³Rancho San Diego Animal Hospital, El Cajon, California 92019

Herpesvirus infections have been reported in a variety of tortoises including Greek (Testudo graeca) and Hermann's (Testudo hermanni) tortoises in Europe, Chilean tortoises imported into the United States from South America and several species of tortoises imported into Japan for the pet trade (Drury et al, 1998, Jacobson et al, 1985, Muro et al, 1998, Une et al 1999) . Herpesvirus infections also have been reported in captive desert tortoises (Gopherus agassizii) (Harper et al, 1982, Pettan Brewer et al, 1996). Until now, the virus infecting desert tortoises has not been isolated or sequenced. Thus, comparisons have not been made between herpesvirus infecting desert tortoises and isolates from Greek and Hermann's tortoises. Recently, a desert tortoise owned by the San Diego Turtle and Tortoise Society was submitted to a consulting veterinarian for clinical evaluation. The tortoise had emerged at an unusual time from hibernation and exhibited anorexia and lethargy. Upon clinical examination, necrotizing lesions were observed in the oral cavity, with the tongue extensively affected. Biopsies were obtained and submitted to the College of Veterinary Medicine, University of Florida for light microscopic evaluation, viral isolation attempts, and gene. Light microscopy revealed epithelial cell necrosis and proliferation. Many epithelial cells contained intranuclear inclusions consistent with those seen in herpesvirus infections. Using a set of consensus primers used to detect herpesvirus in multiple species of animals (VanDevanter et al, 1996), a 215 bp segment of the polymerase gene was amplified. A set of primers designed specifically for the ribonucleotide reductase (RR) gene of herpesvirus found in a Hermann's tortoise was also used successfully to amplify a 386 bp segment. Subsequent sequencing of both products were compared to existing known sequences of genes and found to be most closely related to other tortoise herpesviruses. Comparisons made with isolates from Hermann's tortoises indicated a 72% homology with the RR gene. Viral isolation attempts are in progress. Isolation of the herpesvirus in desert tortoises will be important in interpreting ELISA testing that is currently ongoing. Once the virus is isolated, it will be purified and used as the antigen in the test. Transmission studies are necessary to demonstrate a causal relationship between this virus and disease in desert tortoises.

References

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