1. US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, Maryland, USA.
2. Henry M. Jackson Foundation for the Advancement of Military Medicine, Bethesda, Maryland, USA.
3. Vaccine Trial Centre, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
4. Royal Thai Army Component, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.
5. Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand.