1. Department of Virology, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
2. Section of Immunology, Department of Medical Sciences, National Institute of Health, Nonthaburi 11000, Thailand
3. Laboratory of Pathology, Osaka Prefectural Institute of Public Health, Higashinari-ku, Osaka 537-0025, Japan