1. Division of Microbiology; Department of Pathology and Microbiology; Nihon University School of Medicine; Tokyo Japan
2. Department of Developmental Medical Sciences; School of International Health, Graduate School of Medicine; The University of Tokyo; Tokyo Japan
3. Department of Microbiology; Faculty of Medicine; Chiang Mai University; Chiang Mai Thailand
4. Department of Virology II; National Institute of Infectious Disease; Tokyo Japan