[1] Wageningen Univ Res, Cent Vet Inst, Div Virol, NL-8219 PH Lelystad, Netherlands
[2] Ist Super Sanita, I-00161 Rome, Italy
[3] Agence Francaise Securite Sanit Aliments, F-94706 Maisons Alfort, France
[4] Cent Sci Lab, York YO41 1LZ, N Yorkshire, England
[5] Danish Inst Food & Vet Res, DK-2860 Copenhagen, Denmark
[6] Univ Liege, Fac Vet Med, Dept Food Sci, B-4000 Liege, Belgium
[7] RIVM, Lab Zoonoses & Environm Microbiol, NL-3720 BA Bilthoven, Netherlands