Development of a Quantitative PCR Diagnostic Test for a Novel Adrenal Coccidian Parasite of Leatherback Sea Turtles, (Dermochelys coriacea)
American Association of Zoo Veterinarians Conference 2014
Sara D. Ferguson1; Brian A. Stacy2, DVM, DACVP; Salvatore Frasca Jr3, VMD, PhD, DACVP; Charles J. Innis4, VMD, DABVP (Reptiles and Amphibians); April L. Childress1; James F.X. Wellehan Jr1, DVM, PhD, DACZM, DACVM (Virology, Bacteriology/Mycology)
1College of Veterinary Medicine, University of Florida, Gainesville, FL, USA; 2NOAA, NMFS, Office of Protected Resources, Gainesville, FL, USA; 3Northeastern Research Center for Wildlife Diseases, Department of Pathobiology and Veterinary Science, University of Connecticut, Storrs, CT, USA; 4New England Aquarium, Central Wharf, Boston, MA, USA
Abstract
Leatherback turtles (Dermochelys coriacea) are the most critically endangered sea turtle species, with populations decreasing over 70% globally in less than one generation.1 Recently, a novel parasite has been identified histologically in adrenal lesions. While this parasite does not present with typical coccidian morphology, consensus PCR and sequencing yielded a novel coccidian 18S rRNA sequence.2 Bayesian and maximum likelihood phylogenetic analyses identified this as a novel member of the Eimeriidae. A quantitative PCR (qPCR) assay was then designed to determine whether the adrenal lesions corresponded to the coccidian sequence. Specificity was confirmed against leatherback turtle samples without lesions and a variety of other coccidia. Samples taken from various leatherback necropsies known to have the coccidian parasite present were run on the qPCR assay. Copies detected by qPCR correlated significantly with the total histological score with central bodies present, as well as with the overall density with a cellular component. This supports the classification of this parasite as a coccidian life stage, likely a schizont. The development of a qPCR assay greatly decreases the time and cost to test for this parasite and improves the efficiency of diagnosis. This test is useful for screening additional animals and other samples to further understand the life cycle and epidemiology of this adrenal parasite and its possible impacts on the leatherback population as a whole.
Acknowledgments
We thank Morris Animal Foundation for a Morris Veterinary Student Scholars Program award to Sara Ferguson and thank Dr. Ammon Peck for additional student funding.
Literature Cited
1. Spotila J, Dunham A, Leslie A, Steyermark A, Plotkin P, Paladino F. Worldwide population decline of Dermochelys coriacea: are leatherback turtles going extinct? Chelonian Conservation Biology. 1996;2(2):209–222.
2. Wellehan J, Stacy B, Fransca S Jr., Innis CJ. Molecular characterization of a novel coccidian parasite with adrenal gland lesions in leatherback turtles (Dermochelys coriacea). Proceedings of the American Association of Zoo Veterinarians Conference. Knoxville, Tennessee; October 20th–26th, 2007.