1. Department of Virology, Research Institute for Microbial Diseases; Osaka University; Suita Osaka 565-0871 Japan
2. Department of Pathology; National Institute of Infectious Diseases; Shinjuku-ku Tokyo 162-8640 Japan
3. Department of Microbiology, Leprosy Research Center; National Institute of Infectious Diseases; Higashimurayama Tokyo 189-0002 Japan
4. Department of Biochemistry; Nara Medical University; Kashihara Nara 634-8521 Japan