1. Asia Pacific Centre for Animal Health, The University of Melbourne, Cnr. Park Dr. and Flemington Rd., Parkville, Victoria 3052, Australia;
2. Australian Wildlife Health Centre, Healesville Sanctuary, Badger Creek Rd., Healesville, Victoria 3777, Australia;
3. Veterinary Department, Melbourne Zoo, Elliott Ave., Parkville, Victoria 3052, Australia;
4. Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, 250 Princes Hwy., Werribee, Victoria 3030, Australia;
5. Centre for Equine Infectious Diseases, The University of Melbourne, Cnr. Park Dr. and Flemington Rd., Parkville, Victoria 3052, Australia;
6. These authors contributed equally;