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Identification of a novel Neorickettsia species in a Kemp's ridley sea turtle with granulomatous nephritis and development of a quantitative PCR assay
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  • James F.X. Wellehan,
  • Brittany L. Liguori,
  • Brian A. Stacy,
  • Peter U. Fischer,
  • Kerstin Fischer,
  • Linda L. Archer,
  • April L. Childress,
  • Donna J. Shaver,
  • Subhashinie Kariyawasam
James F.X. Wellehan
University of Florida College of Veterinary Medicine
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Brittany L. Liguori
University of Florida College of Veterinary Medicine
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Brian A. Stacy
NOAA Fisheries
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Peter U. Fischer
Washington University in St Louis
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Kerstin Fischer
Washington University in St Louis
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Linda L. Archer
University of Florida College of Veterinary Medicine
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April L. Childress
University of Florida College of Veterinary Medicine
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Donna J. Shaver
National Park Service
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Subhashinie Kariyawasam
University of Florida College of Veterinary Medicine
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Abstract

An adult male Kemp’s ridley was found dead on the coast of Kenedy County, Texas in August 2019 with bilateral severe, diffuse granulomatous nephritis. Pan-bacterial 16S rRNA gene PCR and amplicon sequencing of affected tissue indicated the presence of a Neorickettsia. Neorickettsia is a genus of obligate intracellular Alphaproteobacteria that are transmitted by digenean trematodes. For further characterization, primers were designed to amplify and sequence the groEL gene. Phylogenetic analysis found that the organism was distinct from other known species to a degree consistent with a novel species. Immunohistochemistry using an antibody directed against a Neorickettsia surface protein showed bacterial clusters within the renal granulomas. A species-specific quantitative PCR was designed, and detected the organism within the liver and colon of the index case. A qPCR survey of grossly normal kidneys opportunistically collected from additional stranded sea turtle kidneys detected this organism in five of 15 Kemp’s ridley turtles, two of nine green turtles, and neither of two loggerhead turtles. Recognition of this novel organism in an endangered species is concerning; additional work is underway to further characterize the potential of this organism as a pathogen of sea turtles.
26 Jul 2022Submitted to Transboundary and Emerging Diseases
02 Aug 2022Submission Checks Completed
02 Aug 2022Assigned to Editor
20 Aug 2022Reviewer(s) Assigned
22 Sep 2022Review(s) Completed, Editorial Evaluation Pending
22 Sep 2022Editorial Decision: Revise Minor
30 Sep 20221st Revision Received
01 Oct 2022Assigned to Editor
01 Oct 2022Submission Checks Completed