1. Ibaraki Children's Hospital
2. The Research Center for Hepatitis and Immunology, National Center for Global Health and Medicine
3. Department of Viral Pathogenesis and Controls, National Center for Global Health and Medicine
4. Department of Pediatrics, Kindai University Nara Hospital
5. Department of Pediatric Hepatology and Gastroenterology, Saiseikai Yokohama-city Tobu Hospital
6. Department of Pediatrics, Nagoya University Graduate School of Medicine