1. Department of Microbiology, Faculty of Medicine, Juntendo University, Tokyo, Japan
2. Department of Infection Control Science, Graduate School of Medicine, Juntendo University, Tokyo, Japan
3. School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India
4. Animal Research Center, Sapporo Medical University School of Medicine, Sapporo, Japan
5. Research Centre for Infection Control Science, Juntendo University, Tokyo, Japan