Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut fü Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 1112, D-38104 Braunschweig, , Germany1
University of Ghent, , Belgium2
GBF, Braunschweig, , Germany3
University of Essex, , UK4
FAL, Braunschweig, , Germany5
NERC-Institute of Virology and Environmental Microbiology, Oxford, <, UK6
University of Birmingham, , UK7
University of York, , UK8
University of Athens, , Greece9
IPO-DLO, Wageningen, , The Netherlands10
University of Bergen, , Norway11
University of Milano, , Italy12
Technical University Berlin, , Germany13
School of Biology Georgia, Atlanta, , USA14
For correspondence. Kornelia Smalla. Tel: +49 531 299 3814. Fax: +49 531 299 3013. e-mail: k.smalla{at}bba.de