[1] Univ Helsinki, Fac Vet Med, Dept Food Hyg & Environm Hlth, POB 66, FI-00014 Helsinki, Finland
[2] Univ Helsinki, Fac Vet Med, Dept Vet Biosci, Helsinki, Finland
[3] Univ Helsinki, Haartman Inst, Dept Virol, Helsinki, Finland
[4] Estonian Univ Life Sci, Inst Vet Med & Anim Sci, Dept Basic Vet Sci & Populat Med, Tartu, Estonia
[5] Helsinki Univ Cent Hosp, HUSLAB, Dept Virol & Immunol, Helsinki, Finland
[6] Finnish Food Safety Author Evira, Helsinki, Finland