DAO 90:31-41 (2010)  -  DOI: https://doi.org/10.3354/dao02214

Pathological and immunological responses associated with differential survival of Chinook salmon following Renibacterium salmoninarum challenge

David C. Metzger1,2, Diane G. Elliott1, Andrew Wargo3, Linda K. Park2, Maureen K. Purcell1,*

1Western Fisheries Research Center, US Geological Survey, 6505 NE 65th Street, Seattle, Washington 98115, USA
2Northwest Fisheries Science Center, National Marine Fisheries Service, 2725 Montlake Boulevard East, Seattle, Washington 98112, USA
3Department of Biology, University of Washington, Box 351800, Seattle, Washington 98195, USA
*Corresponding author. Email:

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-γ, 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 (≥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.


KEY WORDS: Bacterial kidney disease · BKD · Histopathology · Reverse-transcriptase quantitative PCR · Interferon · Immune-mediated pathology · Resistance · Tolerance


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Cite this article as: Metzger DC, Elliott DG, Wargo A, Park LK, Purcell MK (2010) Pathological and immunological responses associated with differential survival of Chinook salmon following Renibacterium salmoninarum challenge. Dis Aquat Org 90:31-41. https://doi.org/10.3354/dao02214

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