1. Laboratory of Veterinary Infectious Disease, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
2. Laboratory of Molecular and Cellular Biology, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
3. Gene Research Center, Tokyo University of Agriculture and Technology, Fuchu, Tokyo, Japan
4. Laboratory of Veterinary Microbiology, Faculty of Applied Biological Sciences, Gifu University, Gifu, Gifu, Japan