1. Department of Microbiology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
2. Musashino Research Institute for Immunity, 790 Nishizatozoe, Gusukube, Miyako Island, Okinawa 906-0106, Japan
3. Transdisciplinary Research Organization for Subtropics and Island Studies, University of the Ryukyus, 1 Senbaru, Nishihara, Okinawa 903-0213, Japan