1. Division of Molecular Virology and Oncology, Department of Microbiology, Graduate School of Medicine, University of the Ryukyus, Okinawa, Japan.
2. Wildlife Section, Nature Conservation Department, Hokkaido Institute of Environmental Sciences, Hokkaido, Japan.
3. Department of Pathobiology, School of Veterinary Medicine, Rakuno Gakuen University, Hokkaido, Japan.