The Use of Kidney Biopsy of Broodstock Steelhead Trout (Oncorhyncus Mykiss) to Determine the Status of Bacterial Kidney Disease Infection

Testing of candidate non-lethal sampling methods for detection of Renibacterium salmoninarum in juvenile Chinook salmon Oncorhynchus tshawytscha

“…When a gold standard assay does not exist, a composite reference standard combining several imperfect assays can provide a better perspective on infection status than a single imperfect assay (Naaktgeboren et al 2013). Several investigators have reported that use of results from more than 1 assay -including culture, ELISA, and nPCR (Faisal & Eissa 2009), ELISA and qPCR (Nance et al 2010), FAT and histopathology/ immunohistochemistry (White et al 1996), ELISA and FAT (Elliott et al 1997), and ELISA, culture, FAT, qPCR, and histopathology (Bruno et al 2007) -can improve evaluations of the presence and stage of R. salmoninarum infections in fish. Second, the kidney assays we used detect different R. salmoninarum analytes, and the occurrence and abundance of these analytes may vary at different stages of infection (Meyers et al 1993, Hamel & Anderson 2002, Cvitanich 2004, Faisal & Eissa 2009, Nance et al 2010, Kent et al 2013.…”

“…As a single gold standard assay has not been identified for detection and quantification of R. salmoninarum (Elliott et al 2013), and researchers have reported that use of data from more than 1 assay can provide complementary information resulting in improved assessment of R. salmoninarum infection status or stage (White et al 1996, Elliott et al 1997, Bruno et al 2007, Faisal & Eissa 2009, Nance et al 2010, we employed composite reference standards (Naaktgeboren et al 2013) for comparison of results between lethal kidney assays and non-lethal assays in addition to the comparisons between individual assays previously described. The kidney assays we used differ in estimated diagnostic sensitivity (Elliott et al 2013, Kent et al 2013, and results from these assays generally show greater concordance and correlation as infection intensity increases (Powell et al 2005, Bruno et al 2007, Nance et al 2010, Elliott et al 1997, Arnason et al 2013, with the highest agreement observed for severe active infections.…”

“…Several types of samples have been successfully employed for non-lethal detection of bacterial, viral, and parasitic pathogens in fish. Among the sample types that have been used for non-lethal pathogen detection in salmonids are fin clips (Skirpstunas et al 2006, Cornwell et al 2013, gill tissue snips (Badil et al 2011), blood samples (Altinok et al 2001, Giray et al 2005, López-Vázquez et al 2006, kidney biopsies (Noga et al 1988, White et al 1996, and mucus samples (LaPatra et al 1989, Cipriano et al 1992, Douglas-Helders et al 2001. Few of these candidate nonlethal samples have been tested for R. salmoninarum detection, however.…”

“…Few of these candidate nonlethal samples have been tested for R. salmoninarum detection, however. Kidney tissue is a standard lethal sample for R. salmoninarum detection (OIE 2003, Fisheries and Oceans Canada 1984, revised 2004, AFS-FHS 2014, and has been em ployed for non-lethal detection of R. salmoninarum in adult steel head trout Oncorhynchus mykiss by FAT and histopathology/ immunohistochemistry (White et al 1996). Sensitive detection of this pathogen in blood samples has been reported for ELISA (Pascho et al 1987) and PCR (Rhodes et al 1998, Bruno et al 2007.…”