1. United States Department of Agriculture, Agricultural Research Service, Avian Disease and Oncology Laboratory, East Lansing, Michigan.
2. College of Animal and Veterinary Science, Jilin University, Changchun, China.
3. Institute of Military Veterinary, Academy of Military Medical Sciences, Changchun, China.
4. Department of Animal Science, Michigan State University, East Lansing, Michigan.
5. Department of Pathobiology and Diagnostic Investigation, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan.
6. Diagnostic Center for Population and Animal Health, Michigan State University, East Lansing, Michigan.