1 Molecular Microbiology Section, Laboratory of Clinical Infectious Diseases, National Institutes of Allergy and Infectious Diseases, NIH, Bethesda, MD 20892, USA. june_kwonchung@nih.gov.
2 Second Department of Internal Medicine, Nagasaki University Hospital, Sakamoto 1-7-1, Nagasaki-city 851-8501, Japan. t-saijo@nagasaki-u.ac.jp.