1. International Centre for Diarrhoeal Disease Research, Dhaka, Bangladesh
2. Department of Microbiology and Immunology and Research Center for Infectious Diseases, Aichi Medical University School of Medicine, Aichi, Japan
3. Central Research Laboratories, Seikagaku Corporation, Tokyo, Japan
4. Department of Microbiology and Immunology and Research Center for Infectious Diseases, Aichi Medical University School of Medicine, Aichi, Japan,