Harmonization and validation of diagnostic protocols for the detection of grapevine viruses covered by phytosanitary rules

The Italian Ministry of Agriculture funded in 2009 the “ARNADIA” Project, aimed at producing validated reference diagnostic protocols for the control and monitoring of plant pathogens of phytosanitary interest and, among them, grapevine viruses. In this framework, the “Working group ARNADIA – grapevine viruses (WG)”, composed of eight universities and research bodies, three accredited private laboratories, one plant health service and one association of grapevine nurseries, was established. The aim of the WG was to produce referenced and validated serological and molecular protocols allowing for the harmonization of diagnosis of eight grapevine viruses: Grapevine leafroll-associated virus 1, 2, 3, (GLRaV 1, 2, 3) Grapevine virus A (GVA), Grapevine virus B (GVB), Arabis mosaic virus (ArMV), Grapevine fanleaf virus (GFLV) and Grapevine fleck virus (GFkV). Specifically, 122 grapevine samples (varieties, rootstocks and “pools” of five plants, of which only one infected) were analyzed by ELISA, using 25 antisera from three commercial companies (Agritest, Bioreba, Sediag) and multiplex RTPCR protocols. ELISA proved to be a highly effective technique, comparable to the molecular method, although the latter turned out, as expected, to be more efficient for some viruses and on some specific samples (rootstocks and “pool”).