Brood stock segregation of spring Chinook salmon Oncorhynchus tshawytscha by use of the enzyme-linked immunosorbent assay (ELISA) and the fluorescent antibody technique (FAT) affects the prevalence and levels of Renibacterium salmoninarum infection in progeny

Detection and Quantification of Renibacterium Salmoninarum DNA in Salmonid Tissues by Real-Time Quantitative Polymerase Chain Reaction Analysis

“…Kidney tissue samples positive for R. salmoninarum were assigned to low, medium, or high antigen amount categories on the basis of previous studies in which ELISA absorbances were compared with the concentrations of R. salmoninarum determined by the FAT and bacteriologic culture. 11,19 The ELISA absorbance (OD 405 ) ranges for these categories were: 0.074 to 0.199 (low), 0.200 to 0.999 (medium), and $1.000 (high).…”

“…24 In general, the levels of ECP in fish correlate with the severity of an R. salmoninarum infection. 19 Because primary isolation of the slowly replicating and fastidious R. salmoninarum in bacteriologic culture can require 6 to 19 weeks 1 and is often impractical for routine diagnosis, several nonculture methods have been developed for detection of the bacterium in fish populations. One commonly used method is the enzyme-linked immunosorbent assay (ELISA), which uses specific immunoglobulin to quantify the amount of MSA 24 or components of the ECP.…”

“…The DNA was extracted by use of the aforementioned kit b according to the manufacturer's instructions for bacteria. To determine the sensitivity of the qPCR, concentrations of R. salmoninarum representing a range between 1 cell and 10 7 cells/reaction were mixed with PBS buffer or with homogenized kidney tissue from adult Chinook salmon that had undetectable amounts of R. salmoninarum on the basis of prior testing by use of the ELISA II procedure 19 and nested PCR assay. 4 Kidney tissues from 38 juvenile Chinook salmon in a population naturally infected with R. salmoninarum were tested by the ELISA, the nested PCR, and the qPCR.…”

“…Unconjugated and horseradish peroxidase-conjugated polyclonal goat immunoglobulin to R. salmoninarum a and a positive-control antigen a were used at the same concentrations as described elsewhere. 19 The negative-positive threshold absorbances were calculated 18 ; the negativepositive absorbance for kidney tissue was 0.073. Kidney tissue samples positive for R. salmoninarum were assigned to low, medium, or high antigen amount categories on the basis of previous studies in which ELISA absorbances were compared with the concentrations of R. salmoninarum determined by the FAT and bacteriologic culture.…”

“…A double-antibody ELISA (ELISA II) 19 that measures the amount of a soluble antigen fraction of R. salmoninarum was used to test the fish kidney homogenates. Unconjugated and horseradish peroxidase-conjugated polyclonal goat immunoglobulin to R. salmoninarum a and a positive-control antigen a were used at the same concentrations as described elsewhere.…”