1 Development Department, Vaccine Division, The Chemo-Sero-Therapeutic Research Institute (KAKETSUKEN), Kita-ku Kumamoto-shi, Kumamoto, Japan yokote@kaketsuken.or.jp.
2 Development Department, Vaccine Division, The Chemo-Sero-Therapeutic Research Institute (KAKETSUKEN), Kita-ku Kumamoto-shi, Kumamoto, Japan.