1. Department of Microbiology, School of Pharmaceutical Sciences; University of Shizuoka; Shizuoka Shizuoka 422 Japan
2. Department of Parasitology; Asahikawa Medical College; Asahikawa Hokkaido 078 Japan
3. Gamaleya Institute of Epidemiology and Microbiology; Russian Academy of Medical Sciences; Moscow 123098 Russia