PKD diagnostic results from an Interlaboratory Proficiency Test

In this study we present the results obtained from an Interlaboratory Proficiency Test (ILPT) for the detection of the parasite Tetracapsuloides bryosalmonae, the causative agent of proliferative kidney disease (PKD). This parasitic disease is widespread in fish populations in Europe and North America, causing significant economic losses in farmed fish and affecting wild fish populations, therefore the implementation of harmonised reliable diagnostic methods is needed. This proficiency test was designed and conducted to optimise and harmonise existing diagnostic methods for detec-tion of T. bryosalmonae across countries, strengthening the diagnostic capacity in Europe. A set of blind samples were distributed to the participating laboratories, representing both diagnostic and research university laboratories and laboratories belonging to the network of National Reference Laboratories for fish diseases involved in surveillance activities and official controls. Each partici¬pant had two tasks: (1) detection of the causative agent, T. bryosalmonae, in kidney tissue by im- munohistochemistry (IHC) and (2) detection of T. bryosalmonae DNA by PCR. IHC results showed that the commercial antibody used is robust and works well in different protocols. The results also suggested that the optimised real-time PCR protocol is robust and showed good sensitivity. Based on these results, we provide recommendations to harmonise the diagnostic protocols currently in use for the detection of T. bryosalmonae.