1. Department of Virology III, Laboratory Animals, and Pathogen Bank, National Institute of Infectious Disease, Musashimurayama, Tokyo, Japan
2. Management Department of Biosafety, Laboratory Animals, and Pathogen Bank, National Institute of Infectious Disease, Musashimurayama, Tokyo, Japan
3. Department of Pediatrics, School of Medicine, Fukushima Medical University, Fukushima, Japan
4. Hoshi General Hospital, Koriyama, Fukushima 963-8501, Japan
5. Ohara General Hospital, Fukushima, Japan