[1] SEAL REHABIL & RES CTR, 9968 AG PIETERBUREN, NETHERLANDS
[2] INST ANIM HLTH, PIRBRIGHT LAB, WOKING GU24 0NF, SURREY, ENGLAND
[3] UNIV VALENCIA, FAC BIOL SCI, DEPT ANIM BIOL, E-46100 BURJASSOT, SPAIN
[4] NATL BACTERIOL LAB, DEPT VIROL, S-10521 STOCKHOLM, SWEDEN
[5] UNIV UTRECHT, UTRECHT, NETHERLANDS
[6] KAROLINSKA INST, S-10521 STOCKHOLM, SWEDEN