Northwest Fisheries Science Center

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Document Type: Journal Article
Center: NWFSC
Document ID: 1100
Title: Pathological and immunological responses associated with differential survival of Chinook salmon following Renibacterium salmoninarum challenge
Author: David C. Metzger, Diane G. Elliott, Andrew Wargo, Linda K. Park, Maureen K. Purcell
Publication Year: 2010
Journal: Diseases of Aquatic Organisms
Volume: 90
Issue: 1
Pages: 31-41
Keywords: bacterial kidney disease (BKD), histopathology, reverse-transcriptase quantitative PCR, interferon, immune-mediated pathology, resistance tolerance
Abstract: Chinook salmon Oncorhynchus tshawytscha are highly susceptible to Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD). Previously we demonstrated that introduced Chinook salmon from Lake Michigan, Wisconsin (WI), USA, have higher survival following R. salmoninarum challenge relative to the progenitor stock from Green River, Washington, USA. In the present study, we investigated the pathological and immunological responses that are associated with differential survival in the 2 Chinook salmon stocks following intra-peritoneal R. salmoninarum challenge of 2 different cohort years (2003 and 2005). Histological evaluation revealed delayed appearance of severe granulomatous lesions in the kidney and lower overall prevalence of membranous glomerulopathy in the higher surviving WI stock. The higher survival WI stock had a lower bacterial load at 28 d post-infection, as measured by reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR). However, at all other time points, bacterial load levels were similar despite higher mortality in the more susceptible Green River stock, suggesting the possibility that the stocks may differ in their tolerance to infection by the bacterium. Interferon-gamma, inducible nitric oxide synthase (iNOS), Mx-1, and transferrin gene expression were up-regulated in both stocks following challenge. A trend of higher iNOS gene expression at later time points (> or = 28 d post-infection) was observed in the lower surviving Green River stock, suggesting the possibility that higher iNOS expression may contribute to greater pathology in that stock.
Official Citation: Metzger, D. C., D. G. Elliott, A. Wargo, L. K. Park, M. K. Purcell. 2010. Pathological and immunological responses associated with differential survival of Chinook salmon following Renibacterium salmoninarum challenge. Dis Aquat Organ. 2010 May 18;90(1):31-41.