1 National Research Center for Protozoan Diseases, Obihiro University of Agriculture and Veterinary Medicine, Nishi 2-13, Inada-cho Obihiro, Hokkaido, Japan 080-8555.
2 Department of Parasitology, University of the Philippines, Manila, Philippines .
3 Laboratory of Molecular Immunology, University of Tokyo, Tokyo, Japan .
4 Laboratory of Tropical Medicine and Parasitology, Dokkyo Medical University, Tochigi, Japan .