Affiliation: | a Laboratory of Animal Experiments, Institute of Immunological Science, Hokkaido University, Sapporo 060-0818, Japan b Laboratory of Microbiology, Department of Disease Control, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo 060-0815, Japan c Division of Veterinary Microbiology, Kyoto Biken Laboratories, Uji 611-0041, Japan |