Building an international network of collections for reference of regulated and other important plant viruses and viroids (VirusCollect II)

The aim of the VirusCollect II project was to establish and extend an international network of collections of plant viruses and viroids thereby making virus isolates available for reference at diagnostic and research laboratories in Plant Health. At present access to isolates of regulated viruses is limited and only the plant virus collection at DSMZ is officially accredited as reference producer.

Strengthening the infrastructure of plant virus collections is required because diagnostic tests on regulated organisms have to be accredited under the new Plant Health rules of the European Union that apply from December 14^th 2019. The ability of laboratories of National Plant Protection Organizations (NPPOs) to fulfil this requirement will depend on public access to well-characterised virus isolates.

The collaboration between partners of the Euphresco projects NGS-detect and VirusCollect II and especially their joint meetings offered a fruitful platform for exchanging practices in characterisation and safeguarding of virus isolates for reference. Discussions on practices in High-throughput sequencing (HTS) and analysis, and on quality criteria for reference materials contributed to a common understanding of procedures, as well as to identify future needs and functions of plant virus collections.

Within the project more than 150 isolates of regulated and (related) non-regulated viruses have been made available. However, since identification of many isolates was based on only one technique, and/or sequence data were lacking or limited, not all of them qualify as reference material yet. Whether these isolates will be included in Q-bank depends on the criteria imposed on completeness of data and certainty of identification. The transfer of Q-bank to EPPO ensures the continuity of a platform for sharing data on availability and location of virus isolates for diagnostics and research.

Two successive VirusCollect projects have made clear that plant virus collections are not on the priority list of policy makers and researchers. Only those partners that benefited from allocated budgets were able to contribute substantially to Q-bank by characterising isolates and making them publicly accessible and available. In addition, the implementation of the Nagoya protocol appeared to increase administrative obligations of both curators and users of collection materials. Therefore, governments need to allocate specific budgets for the characterisation and maintenance of virus collections to enable NPPO laboratories to perform their official tasks.