1. Department of Microbiology, Faculty of Medicine, Srinakharinwirot University, Bangkok, Thailand.
2. Department of Microbiology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
3. Center of Excellence in Clinical Virology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
4. GlaxoSmithKline Biologicals, Rixensart, Belgium.
5. Division of Allergy and Clinical Immunology, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.