1. Department of Hygiene, Kanazawa University, Graduate School of Medical Science, Kanazawa, Japan.
2. Department of Viral Infection and International Health, Kanazawa University, Graduate School of Medical Science, Kanazawa, Japan.
3. Hai Phong Medical University, Hai Phong, Viet Nam.
4. Department of Medical microbiology, Hanoi Medical University, Hanoi, Viet Nam.
5. AIDS Research and Clinical Center, International Medical Center of Japan, Tokyo, Japan.