1. The Pirbright Institute, Pirbright, Surrey, United Kingdom;
2. Société de Productions Pharmaceutiques et Vétérinaires, Laboratoire de Virologie, Rabat, Morocco;
3. China Animal Health and Epidemiology Center, Qingdao, Shandong, People's Republic of China;
4. Animal Health and Veterinary Laboratories Agency, Weybridge, Surrey, United Kingdom