Basic research is helping scientists better understand how microbes spread by contaminated food or water cause disease in humans.
National Institute of Allergy and Infectious Diseases (NIAID)-supported researchers are studying the bacterial genes that help pathogens (germs) establish themselves in the human body and cause disease. For example, scientists have identified genes that appear to be involved in signaling certain immune system cells to cause inflammation and may contribute to the development of diarrhea.
Other NIAID-sponsored research focuses on methods by which the organism grows and interacts in cells. Scientists have discovered that some intestinal bacteria recognize when they are in a human and respond by activating a particular set of powerful genes that enable the organism to live in the body and cause disease. Future studies will define new ways to intervene, whether by prevention or treatment, in the disease process.
Scientists have determined the complete genome (genetic blueprint) sequences for Salmonella typhi, Salmonella typhimurium, Escherichia coli O157:H7, and Campylobacter jejuni. Sequencing studies are underway for Shigella, Yersinia, as well as other harmful strains of E. coli. Scientists hope this new information will speed the discovery of new targets for treatments and vaccines against foodborne pathogens.
Through preliminary tests of live, attenuated (weakened) S. flexneri vaccine candidates, scientists have discovered two new toxins that may contribute to the diarrhea associated with Shigella. Studies are under way to find out how these toxins cause fluid loss. The findings will provide crucial information on how to improve attenuated vaccines to prevent shigellosis.
Researchers are developing vaccines to prevent Shigella infections in animals or humans. Scientists also are developing and testing monoclonal antibodies to treat Shiga toxin (poison) infection, which can severely damage the lining of intestines and kidneys.
Investigators are further defining the ways by which the toxins produced by Shigella result in the kidney damage leading to hemolytic uremic syndrome (HUS), a life-threatening condition. The primary goal of this research is to better understand how kidney disease progresses. In addition, researchers are developing antitoxins that may help prevent HUS from developing.
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