1. Department of Bacterial and Parasitic Diseases, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
2. Division of Research, Armed Forces Research Institute of Medical Sciences, Bangkok, Thailand
3. Department of Pediatrics, Center for Vaccine Development and Global Health, University of Maryland School of Medicine, Baltimore, Maryland, USA
4. Bacterial Diseases Branch, Center for Infectious Diseases Research, Walter Reed Army Institute of Research (WRAIR), Maryland, USA