Journal article
Isolation of Tasmanian Rickettsia-like organism (RLO) from farmed salmonids: Identification of multiple serotypes and confirmation of pathogenicity
RN Morrison, ND Young, G Knowles, MC Cornish, J Carson
Diseases of Aquatic Organisms | INTER-RESEARCH | Published : 2016
DOI: 10.3354/dao03057
Abstract
Atlantic salmon Salmo salar L. farmed in south-east Tasmania, Australia, are susceptible to infection by the Tasmanian Rickettsia-like organism (TRLO), a Gram-negative bacterium. Here, we report the first isolation of TRLO from south-east Tasmania in pure culture and show that the bacterium is culturable on both specialised enriched agar and in cell culture using the CHSE- 214 cell line. In vitro cultured TRLO was used to reproducibly elicit disease in Atlantic salmon parr held in fresh water. In inoculated fish, TRLO was observed intracytoplasmically in peripheral blood leucocytes, suggesting that these cells are responsible for haematogenous dispersal of the bacterium within the host. Fish..
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Funding Acknowledgements
This project was supported by funding from the Fisheries Research and Development Corporation on behalf of the Australian Government, the Tasmanian Salmonid Growers' Association (TSGA) and the State Government of Tasmania through the Department of Primary Industries, Parks, Water and Environment. We thank Pheroze Jungalwalla and Dr. Adam Main (TSGA) for their support of this project. We also thank the following DPIPWE staff: Kevin Ellard and Robert Chandler for their assistance with field work through the Tasmanian Salmonid Health Surveillance Program (TSHSP), Dr. Marianne Douglas and Susan Renilson (molecular diagnostics), Rebecca Wilkes (media preparation), and Dane Hayes, Catherine Marshall and Belinda Jones (histology and IHC). All farms gave generous access to fish for samples. Special mention goes to Dr. Steve Percival (Huon Aquaculture Co.), David Kiemele (Tassal Ltd.), Lance Hubbert (Tassal Ltd.) and Mick Hortle (Van Diemen Aquaculture) for providing assistance with field work in addition to the TSHSP sampling.