[1] INTA, EEA Rafaela, Santa Fe, Argentina
[2] Consejo Nacl Invest Cient & Tecn, RA-1033 Buenos Aires, DF, Argentina
[3] Univ Nacl Litoral, Fac Bioquim & Ciencias Biol, Santa Fe, Argentina
[4] Uppsala Univ, Dept Clin Virol, Uppsala, Sweden
[5] Univ Nacl Litoral, Fac Ciencias Vet, Esperanza, Santa Fe, Argentina