1. Laboratory of Cell Pathobiology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan
2. Veterinary Medical Center, Osaka Prefecture University, Osaka, Japan
3. Present address: Veterinary Medical Center, Osaka Metropolitan University, Osaka, Japan
4. Laboratory of Veterinary Pathology, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, Japan
5. Hirai Animal Hospital, Osaka, Japan
6. Present address: Laboratory of Cell Pathobiology, Graduate School of Veterinary Sciences, Osaka Metropolitan University, Osaka, Japan