1. Laboratory of Bacteria Microbiology and Immunology Department; Pasteur Institute of Ho Chi Minh City; 167 Pasteur Street District 3 Ho Chi Minh City Vietnam
2. Department of Bacteriology I; National Institute of Infectious Diseases; 1-23-1 Toyama Shinjuku Tokyo 162-8640 Japan
3. Center for Infectious Disease Research in Asia and Africa; Institute of Tropical Medicine; Nagasaki University; 1-12-4 Sakamoto Nagasaki City Nagasaki 852-8523 Japan
4. Vietnam Research Station; Institute of Tropical Medicine; Nagasaki University; c/o National Institute of Hygiene and Epidemiology; 1 Yersin Street Hanoi Vietnam