Inter-Research > DAO > v91 > n2 > p113-119  
Diseases of Aquatic Organisms

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DAO 91:113-119 (2010)  -  DOI:

Interpreting dual ELISA and qPCR data for bacterial kidney disease of salmonids

Shelly L. Nance1, Michael Riederer2, Tyler Zubkowski3, Marc Trudel3, Linda D. Rhodes4,*

1Aquatic Farms, Ltd., 49–139 Kamehameha Highway, Kaneohe, Hawaii 96744, USA
2Department of Biology, University of Washington, Seattle, Washington 98195, USA
3Pacific Biological Station, Department of Fisheries and Oceans, 3190 Hammond Bay Road, Nanaimo, British Columbia V9T 6N7, Canada
4Northwest Fisheries Science Center, National Marine Fisheries Service, 2725 Montlake Blvd. East, Seattle, Washington 98112, USA
*Corresponding author. Email:

ABSTRACT: Although there are a variety of methods available for the detection of Renibacterium salmoninarum, the causative agent of bacterial kidney disease in salmon and trout, the enzyme-linked immunosorbent assay (ELISA) is probably the most widely used method. However, ELISA measures bacterial antigen, which does not necessarily reflect the number of cells present. We hypothesized that dual analysis of kidney tissue by ELISA and a quantitative real-time polymerase chain reaction assay (qPCR) would provide complementary information about antigen level and the number of bacterial genomes. We found that DNA extracted from the insoluble fraction of the ELISA tissue preparation produced the same qPCR result as DNA extracted directly from frozen tissue, permitting true dual analysis of the same tissue sample. We examined kidney tissue in this manner from individual free-ranging juvenile Chinook salmon and antibiotic-treated captive subadult Chinook salmon and observed 3 different patterns of results. Among the majority of fish, there was a strong correlation between the ELISA value and the qPCR value. However, subsets of fish exhibited either low ELISA values with elevated qPCR values or higher ELISA values with very low qPCR values. These observations suggest a conceptual model that allows inferences about the state of infection of individual fish based on dual ELISA/qPCR results. Although this model requires further assessment through experimental infections and treatments, it may have utility in broodstock  selection programs that currently apply egg-culling practices based on ELISA alone.

KEY WORDS: Bacterial kidney disease · Renibacterium salmoninarum · Diagnostic assays · ELISA · qPCR · Infection state · Oncorhynchus tshawytscha

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Cite this article as: Nance SL, Riederer M, Zubkowski T, Trudel M, Rhodes LD (2010) Interpreting dual ELISA and qPCR data for bacterial kidney disease of salmonids. Dis Aquat Org 91:113-119.

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