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Validation of diagnostic tests to support plant health

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Shaping the future of plant pest diagnostics in the EU

A multidisciplinary consortium is championing the fight against plant pests by enhancing the reliability of tests used for their detection and identification.

Food and Natural Resources

Each year, approximately 40 % of global food crops are lost due to pests and diseases. This has a detrimental effect on food security, the sustainability of agriculture and the economy. Quick, accurate and reliable detection and identification of pests are crucial to tackling this issue. However, such tests are mostly validated on an intra-laboratory basis or through limited test performance studies, putting into question their quality and validity as well as highlighting the need for harmonised test validation processes. The EU-funded VALITEST project set out to change this. “Our main objective was to improve the reliability of plant pest diagnostics,” explains Mathieu Rolland, deputy project coordinator. To achieve this, the project’s first goal was to complement existing or produce new validation data for the detection and identification of plant pests that are of interest to various stakeholders. This is alongside the goals of harmonising procedures and encouraging and improving the interactions between stakeholders for better diagnostics.

Transforming diagnostics

Validation data is not available for all the tests used in plant pest diagnostic laboratories. Therefore, to ensure the quality and validity of results, additional validation data is required. Meeting this need, the project organised 2 rounds of test performance studies, whereby the performance of 83 detection tests covering 11 pests and including about 10 000 samples were analysed. “As a result, we have generated validation data for these priority pests, and in the process validation procedures have been enhanced and further harmonised,” notes Rolland. The work of VALITEST has also led to an improved framework, proposing new statistical tools for the analysis of validation data and guidelines, to ensure the reliability of the results obtained with high-throughput sequencing. It will be used to revise relevant European and Mediterranean Plant Protection Organization (EPPO) PM 7/98 and PM 7/122 standards or draft new ones. “We have also developed new guidelines for the production of reference material, which are essential for the reliable validation of tests and for routine diagnostics,” adds Rolland.

The future of testing and plant health

Proficiency evaluation, following a horizontal approach, can aid laboratories in managing and demonstrating their competence and proficiency in testing. Optimising this evaluation, the needs and views of laboratories on horizontal proficiency tests were identified through a survey the project sent to laboratories registered in the EPPO database on diagnostic expertise. Discussions with accreditation bodies have started on a possible plant health approach regarding the level and frequency of proficiency testing in laboratories. “Furthermore, online training activities – webinar series and practical sessions – on the concept of validation, the organisation of test performance studies, and the development, validation and routine use of high-throughput sequencing tests have been organised for diagnostic laboratories,” confirms Rolland. VALITEST aims to bring to market tests that are validated according to international standards and produced by the SMEs manufacturing diagnostic kits. An EU Plant Health Diagnostics Charter describing the quality procedures for the production and the validation of commercial tests produced by EU manufacturers is being developed. This Charter will contribute to guaranteeing the quality and the reliability of products. In parallel, “the project and our partners are laying the foundations for an EU Association of the Plant Health Diagnostic Industry Association,” concludes Rolland. This will ensure the market sustainability of SMEs.

Keywords

VALITEST, diagnostics, plant pest, validation data, plant health, test performance studies, EPPO, plant protection

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