DAO 69:101-110 (2006)  -  doi:10.3354/dao069101

Viruses: agents of coral disease?

S. K. Davy1,2,4,*, S. G. Burchett1,2, A. L. Dale1,3,5, P. Davies1,2,6, J. E. Davy1,7, C. Muncke1,2,7,8, O. Hoegh-Guldberg7, W. H. Wilson1,6

1Marine Biological Association of the UK, Citadel Hill, Plymouth PL1 2PB, UK
2Institute of Marine Studies, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
3School of Biological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, UK
4Present address: School of Biological Sciences, Victoria University of Wellington, PO Box 600, Wellington, New Zealand
5Present address: Department of Zoology, Ecology and Plant Science, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland
6Present address: Plymouth Marine Laboratory, Prospect Place, The Hoe, Plymouth PL1 3DH, UK
7Present address: Centre for Marine Studies, University of Queensland, Brisbane QLD 4072, Australia
8Present address: EM Unit, School of Biomedical Sciences, Nuffield Building, University of Liverpool, Crown Street, Liverpool L69 3BX, UK

ABSTRACT: The potential role of viruses in coral disease has only recently begun to receive attention. Here we describe our attempts to determine whether viruses are present in thermally stressed corals Pavona danai, Acropora formosa and Stylophora pistillata and zoanthids Zoanthus sp., and their zooxanthellae. Heat-shocked P. danai, A. formosa and Zoanthus sp. all produced numerous virus-like particles (VLPs) that were evident in the animal tissue, zooxanthellae and the surrounding seawater; VLPs were also seen around heat-shocked freshly isolated zooxanthellae (FIZ) from P. danai and S. pistillata. The most commonly seen VLPs were tail-less, hexagonal and about 40 to 50 nm in diameter, though a diverse range of other VLP morphotypes (e.g. rounded, rod-shaped, droplet-shaped, filamentous) were also present around corals. When VLPs around heat-shocked FIZ from S. pistillata were added to non-stressed FIZ from this coral, they resulted in cell lysis, suggesting that an infectious agent was present; however, analysis with transmission electron microscopy provided no clear evidence of viral infection. The release of diverse VLPs was again apparent when flow cytometry was used to enumerate release by heat-stressed A. formosa nubbins. Our data support the infection of reef corals by viruses, though we cannot yet determine the precise origin (i.e. coral, zooxanthellae and/or surface microbes) of the VLPs seen. Furthermore, genome sequence data are required to establish the presence of viruses unequivocally.


KEY WORDS: Viruses · Corals · Zooxanthellae· Coral disease · Coral health · Stress


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