1. Department of Veterinary HygieneVeterinary SchoolNippon Veterinary & Life Science UniversityMusashinoTokyoJapan
2. Division of Molecular VirologyDepartment of Microbiology and ImmunologyThe University of TokyoThe Institute of Medical ScienceMinato‐kuTokyoJapan
3. Division of Molecular VirologyDepartment of Microbiology and ImmunologyDaiki Animal HospitalKatsushika‐kuTokyoJapan
4. Department of Veterinary Internal MedicineVeterinary SchoolNippon Veterinary & Life Science UniversityMusashinoTokyoJapan
5. Faculty of MedicineDepartment of BacteriologyJuntendo UniversityBunkyoTokyoJapan