Proteobacteria Associated with Epitheliocystis-Like Inclusions in Two Captive-Born Bonnethead Sharks (Sphyrna tiburo)
IAAAM 2016
Sarah A. Cannizzo1,2*+; Janice B. Harvey3; J. McHugh Law3; Jennifer A. Dill4; Emily F. Christiansen5; Esteban Soto6; Craig A. Harms1,2; Alvin C. Camus4
1Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; 2Center for Marine Sciences and Technology, North Carolina State University, Morehead City, NC, USA; 3Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA; 4Department of Pathology, College of Veterinary Medicine, Aquatic Diagnostic Service Athens, University of Georgia, Athens, GA, USA; 5North Carolina Aquariums, Morehead City, NC, USA; 6Department of Medicine and Epidemiology, School of Veterinary Medicine, University of California-Davis, Davis, CA, USA


Epitheliocystis is a condition affecting gills and skin of teleost fish.1 It refers to basophilic cytoplasmic bacterial "inclusions" identified in the gills.1-4 Lesions consistent with epitheliocystis in elasmobranchs have been reported in hammerhead sharks (Sphyrna spp.), spotted eagle rays (Aetobatus narinari), spiny dogfish (Squalus acanthias), smooth dogfish (Mustelus canis), and a leopard shark (Triakis semifasciata).5-8 Lesions have been historically associated with Chlamydiales species and pan-chlamydial primers have been successfully used to obtain sequence data for a spotted eagle ray and a leopard shark.6,8,9 Recently, advanced diagnostic techniques and molecular analysis have suggested the lesions are actually associated with proteobacteria.2,3 Inclusions morphologically similar to epitheliocystis were found in gills of two captive-born, wild-conceived, bonnethead shark (Sphyrna tiburo) pups. Histopathology of gills revealed typical spherical, granular, basophilic inclusions containing fine filamentous bacterial rods within epithelial cells arising from the lamellae. The organisms are gram negative, and highlighted with Giemsa and Macchiavello stains, but do not stain with periodic acid-Schiff. Immunohistochemistry was performed using monoclonal mouse and polyclonal rabbit anti-chlamydial antibodies, showing strong positive staining with the polyclonal antibody, but not with the monoclonal product. Polymerase chain reactions (PCR) and Sanger sequencing were performed on samples from one pup. Initial PCR with pan-Chlamydiales 16S rRNA gene primers and resultant molecular sequence data support findings that epitheliocystis could be caused by unclassified proteobacteria species. Two adult, wild-caught bonnethead sharks screened for epitheliocystis-like inclusions revealed a similar inclusion indicating that this condition occurs in free-ranging populations.


The authors thank Heather Broadhurst, Hap Fatzinger, Kent Passingham, Emily Peele, and Clint Taylor for their support of this project.

* Presenting author
+ Student presenter

Literature Cited

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Speaker Information
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Sarah A. Cannizzo, DVM
Department of Clinical Sciences
College of Veterinary Medicine
North Carolina State University
Raleigh, NC, USA

Center for Marine Sciences and Technology
North Carolina State University
Morehead City, NC, USA

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