1. Institute of Basic Medical Sciences, University of Tsukuba, Tennodai, Tsukuba, Ibaraki
2. Tsukuba Primate Center for Medical Science, Hachimandai, Tsukuba, Ibaraki
3. Institute of Community Medicine, University of Tsukuba, Tennodai, Tsukuba, Ibaraki
4. Faculty of Agriculture, Gifu University, Yanagido, Gifu
5. National Institute of Animal Health, Kannondai, Tsukuba, Ibaraki, Japan