[1] Hungarian Acad Sci, Vet Med Res Inst, H-1143 Budapest, Hungary
[2] State Publ Hlth Serv, Baranya Cty Inst, Reg Lab Virol, H-7623 Pecs, Hungary
[3] Univ Pecs, Fac Med, Dept Med Genet & Child Dev, H-7624 Pecs, Hungary
[4] Univ Bari, Dept Anim Hlth & Well Being, I-70010 Bari, Italy
[5] Ctr Dis Control & Prevent, Div Viral Dis, Natl Ctr Immunizat & Resp Dis, Atlanta, GA 30333 USA