[1] Royal Vet Coll, Dept Vet Clin Sci, Hatfield AL9 7TA, Herts, England
[2] Colorado State Univ, Dept Clin Sci, Ft Collins, CO 80523 USA
[3] Univ Kentucky, Maxwell H Gluck Equine Res Ctr, Dept Vet Sci, Lexington, KY 40546 USA
[4] Cornell Univ, New York State Coll Vet Med, Ithaca, NY 14853 USA
[5] Univ Saskatchewan, VIDO, Saskatoon, SK S7N 5E3, Canada
[6] Ft Dodge Anim Hlth, Ft Dodge, IA 50501 USA
[7] Anim Hlth Trust, Newmarket CB8 7UU, Suffolk, England
[8] Univ London Royal Vet Coll, London NW1 0TY, England
[9] Inst Anim Hlth, Newbury RG20 7NN, Berks, England
[10] Macquarie Univ, Dept Biol Sci, Sydney, NSW 2109, Australia
[11] Univ Utrecht, Equine Sci Dept, Utrecht, Netherlands
[12] Ohio State Univ, Dept Vet Clin Sci, Columbus, OH 43210 USA
[13] Japan Racing Assoc, Equine Res Inst, Kokubunji, Tochigi 3290412, Japan
[14] Merial, F-69007 Lyon, France
[15] Univ Munich, Inst Med Microbiol Infect & Epidem Dis, Munich, Germany
[16] Louisiana State Univ, Med Ctr, Sch Med, Dept Microbiol & Immunol, Shreveport, LA 71130 USA
[17] Univ Saskatchewan, Western Coll Vet Med, Dept Large Anim Clin Sci, Saskatoon, SK S7N 5B5, Canada
[18] Univ Ghent, Fac Vet Med, Virol Lab, B-9000 Ghent, Belgium
[19] Univ Calif Davis, Sch Vet Med, Dept Med & Epidemiol, Davis, CA 95616 USA