SEOUL—A scientist has discovered one of the mechanisms used by the microorganism Shigella - the bacteria that causes dysentery - to suppress immune responses in humans, thereby facilitating their infection. The study is expected to help accelerate the development of an effective new vaccine against bacillary dysentery.
Dr. Dong Wook Kim at the International Vaccine Institute (IVI, Director General: Dr. John Clemens) found that one of the secreted proteins from Shigella down-regulates the human immune responses and dodges the process to remove the pathogen. The study, which Dr. Kim lead- authored, appears in the September 27 issue of the Proceedings of the National Academy of Sciences (PNAS), one of the world´s leading scientific publications.
Shigellosis is a diarrheal disease caused by Shigella species and transmitted by fecal contamination. The invasion by Shigella of the large intestine in humans sets off an inflammation response, which could result in bloody diarrhea. There are around 150 million Shigella episodes per year worldwide and nearly 1 million deaths, but there is no effective vaccine against the highly infectious disease.
Human immune responses against Shigella are activated by proteins such as NF-kB present in epithelial cells of the intestine. Dr. Kim and his collaborators have discovered a protein of Shigella capable of inhibiting the activation of the NF-kB protein, thus effectively suppressing human immune responses against the dangerous pathogen. Dr. Kim conducted the study at the Pasteur Institute, France, where he served as a visiting fellow supported by the IVI´s program to cultivate talented young Korean scientists.
The IVI, based on the campus of Seoul National University, is striving to develop and introduce new vaccines against Shigella, cholera and typhoid fever as part of its Disease of the Most Impoverished Program, which is funded by the Bill & Melinda Gates Foundation. "The new finding will help spur the IVI´s ongoing efforts to develop a new Shigella vaccine," Dr. Kim said.
The IVI, the world´s only international research organization exclusively devoted to new vaccines for the poorest children, operates laboratory science programs at its headquarters to develop new vaccines, and translational research programs in 21 developing countries worldwide to accelerate the introduction of new vaccines.