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

Experimental challenges with Renibacterium salmoninarum in Arctic charr Salvelinus alpinus

“…Several reports dealing with injection of inactivated or live R. salmoninarum have shown similar findings (Pascho et al 1997, Faisal & Eissa 2009, Nance et al 2010. It can be assumed that lymphoid tissue in the head-kidney and spleen as well as mucosa associated lymphoid tissues in the gut are involved in trapping of the bacterium (Press & Evensen 1999), but it remains an open question whether, or to what extent, the immune system manages to destroy R. salmoninarum and degrade its components.…”

“…There were 3 isolations of the bacterium in cohabitants at Week 7, but none at Week 15. At Week 15, the profile indicated a resolving infection, as modelled previously with kidney samples being ELISA positive and PCR negative (Nance et al 2010). However, it seems that there were still some fish with viable bacterium, as there was an isolation on agar from 1 fish at Week 25 and more PCR tests were positive at Week 34 than at Week 7.…”

Bench‐top validation testing of selected immunological and molecular Renibacterium salmoninarum diagnostic assays by comparison with quantitative bacteriological culture

“…Concordance can also be influenced by differences in R. salmoninarum infection stage in fish at the time of sampling, which can affect the amounts of various analytes present (Cvitanich ; Faisal & Eissa ; Nance et al . ). In naturally infected salmonid populations, fish representing various stages of infection would be expected to be present at the same time (Jansson et al .…”

“…; Faisal & Eissa ; Nance et al . ; Sandell & Jacobson ). A variety of factors have been hypothesized to impact assay concordance.…”

“…; Faisal & Eissa ; Nance et al . ; Sandell & Jacobson ). Experimental exposure of a group of fish to R. salmoninarum on a single date as occurred in our study may result in a reduction or skewing of the spectrum of infection stages manifested in the population.…”