1. 1Laboratory of Microbiology and Immunology, Gifu Pharmaceutical University, Gifu, Japan
2. †Present address: JCR Pharmaceuticals, Hyogo, Japan.
3. ‡Present address: Nagoya City Hall, Aichi, Japan.
4. §Present address: Hanshin Dispensing Pharmacy, Hyogo, Japan.
5. 2Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
6. ¶Present address: Eiken Chemical, Tochigi, Japan.