Bacteria of the genus Shigella cause Shigellosis in humans, a severe diarrheal disease that claims over one million lives each year. In order to survive and cause disease, Shigella must adapt to each unique environment encountered during infection within the human host, and during transmission from one host to the next. The long-term goal of studies in the Murphy laboratory is to characterize the role that regulatory RNA molecules play in mediating the adaptation of Shigella species to environmental conditions encountered upon entry into the human host.