1. Chemicals Assessment and Research Center, Chemicals Evaluation and Research Institute, Saitama, Japan
2. Laboratory of Veterinary Hygiene, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
3. Laboratory of Veterinary Microbiology, Joint Faculty of Veterinary Medicine, Yamaguchi University, Yamaguchi, Japan
4. Special Pathogens Laboratory, Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan