1. 1Federal Research Center for Virology and Microbiology, Pokrov, Russia
2. 2Department of Pathobiology and Veterinary Science and Center of Excellence for Vaccine Research, University of Connecticut, Storrs, Connecticut, USA
3. 3Department of Biomedical Science, College of Veterinary Medicine, Iowa State University, Ames, Iowa, USA
4. †Present address: 10 Xinghuo Road, Jiangbei New Area, Nanjing, PR China.
5. 4School of Veterinary Medicine & Biomedical Sciences and Nebraska Center for Virology, University of Nebraska, Lincoln, Nebraska, USA
6. 5Department of Pathobiology, College of Veterinary Medicine, University of Illinois, Urbana, Illinois, USA