P-603 - Potato virus interlaboratory comparison as external proof of diagnostic laboratory competence

Accreditation of diagnostic laboratories to ISO 17025 (General requirements for the competence of testing and calibration laboratories) means that they must demonstrate their competence in detecting pathogens by regularly participating in interlaboratory comparisons, also known as proficiency testing (PT). The obligation for laboratories to participate and the lack of providers led to the development of a PT organized on their own initiative for the six viruses relevant for seed potato certification: PVY, PLRV, PVM, PVA, PVX and PVS. The PT took place for the first time in 2010 between three laboratories in Germany. This has since evolved into a major international proficiency test, with a total of 55 sample sets sent to 37 participating laboratories in 16 countries worldwide in 2024. This presentation summarizes the development of this PT and discusses the results obtained. Each laboratory participates with its own established protocols, ranging from serological methods (ELISA), arrays and rapid tests to RT-qPCR. This not only provides important information about the competence of the participating laboratories, but also allows comparisons within and between methods. Over the years, many laboratories have switched from the time-consuming cultivation of eye cuttings followed by ELISA to time-saving RT-qPCR on potato tubers. PT has helped to identify shortcomings in published methods for the detection of individual viruses, leading to improved detection reliability.