Detection of T . bryosalmonae in rainbow trout kidney during clinical PKD. ( A ) T. bryosalmonae 18S rDNA relative to trout MCSF (DNA detection); ( B ) T. bryosalmonae RPL18 relative to trout EF-1α (mRNA detection). Average cCq value in grade 1 fish is provided above the bar; ( C ) Correlation between 18S rDNA and RPL18 parasite detection markers is shown (r = 0.94; P < 0.0001); ( D ) Linear relationship of RT-qPCR detection and molar concentration of T. bryosalmonae RPL18. A serial diluted RPL18 internal reference was included in the same PCR run to enable relative quantification.