1. National Research Institute for Veterinary Virology and Microbiology, Russian Academy of Agriculture Science, Pokrov, Russian Federation
2. Department of Pathobiology and Veterinary Science and Center of Excellence for Vaccine Research, University of Connecticut, Storrs, Connecticut, USA
3. United States Department of Agriculture, Agricultural Research Service, Southeast Poultry Research Laboratory, Athens, GA, USA
4. School of Veterinary and Biomedical Sciences and Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
5. Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, IL, USA