1. The Pirbright Institute, Pirbright, Guildford, Surrey, United Kingdom
2. Shandong Binzhou Animal Science and Veterinary Medicine Academy & UK-China Centre of Excellence for Research on Avian Diseases, Binzhou, Shandong, PR China
3. The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
4. Department of Zoology, University of Oxford, Oxford, United Kingdom