DAO 91:75-81 (2010)  -  DOI: https://doi.org/10.3354/dao02255

NOTE
Novel Chlamydiales associated with epitheliocystis in a leopard shark Triakis semifasciata

A. Polkinghorne1,5, H. Schmidt-Posthaus2, A. Meijer3, A. Lehner4, L. Vaughan1,*

1Institute of Veterinary Pathology, University of Zurich, Winterthurerstrasse 268, Zurich 8057, Switzerland
2Centre for Fish and Wildlife Health, Institute of Animal Pathology, University of Bern, Laenggassstrasse 122, Bern 3012, Switzerland
3Diagnostic Laboratory for Infectious Diseases and Screening, National Institute for Public Health and the Environment, PO Box 1, 3720 Bilthoven, The Netherlands
4Institute for Food Safety and Hygiene, University of Zurich, Winterthurerstrasse 272, Zurich 8057, Switzerland
5Present address: Institute of Health and Biomedical Innovation and School of Life Sciences, Queensland University of Technology, 60 Musk Avenue, Kelvin Grove 4059, Australia
*Corresponding author. Email:

ABSTRACT: The Chlamydiales is a diverse order of obligate intracellular gram-negative bacteria that are known to cause a wide range of diseases in terrestrial animals, including humans. Molecular analyses have revealed that these organisms are also associated with epitheliocystis in teleost fish species, highlighting the suspected deep evolutionary origin of members of this bacterial order. However, our knowledge of their fish host range and of the diversity of the bacteria themselves is still very limited. In this study, we provide molecular evidence for a novel member of the Order Chlamydiales in a nonteleost species, the leopard shark Triakis semifasciata. Based on phylogenetic analysis of the 16S rRNA gene, this novel organism appears to represent a unique lineage in the Order Chlamydiales despite appearing histologically similar to epitheliocystis-causing organisms in other fish species. A greater understanding of the genetic diversity of marine Chlamydiales will assist our attempts to manage and control epitheliocystis outbreaks and to understand the evolution of this unique obligate intracellular pathogen.


KEY WORDS: Epitheliocystis · Chlamydia · Leopard shark · 16S rRNA · Phylogenetic analysis · Gill pathology


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Cite this article as: Polkinghorne A, Schmidt-Posthaus H, Meijer A, Lehner A, Vaughan L (2010) Novel Chlamydiales associated with epitheliocystis in a leopard shark Triakis semifasciata. Dis Aquat Org 91:75-81. https://doi.org/10.3354/dao02255

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