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Researchers Find Bacteria Mutation
PHOTO: A three-dimensional reconstruction of the Campylobacter flagellar filament in the foreground, with an electron micrograph of these filaments in the background. Bacteria propel themselves by rotating their flagella, which is key to helping bacteria find food and continue to spread within a host. The structural differences in C. jejuni are significant, Egelman says, because it allows the bacteria to slip under the radar of the vertebrate Toll-like receptor 5 (TLR5). This receptor recognizes a region of the bacterial flagellin and can activate the immune system’s response, killing the bacteria and preventing it from multiplying or causing greater damage. “These bacteria evade the immune response, because they have evolved over millions of years to escape the surveillance system shared by many vertebrates, from fish to humans,” Egelman says. “It was long accepted they had the same structure as other bacteria, but we know this is not the case and it could lead to a major breakthrough in the treatment of diarrhea caused by C. jejuni.” If C. jejuni is able to evade a person’s immune system due to its mutation, the body will not be able to fight off the infection on its own or it could take much longer for the body to rid itself of the infection. Contaminated drinking water and unpasteurized milk are the most common means of transmission of C. jejuni. In addition, contaminated food is a major source of isolated infections, with incorrectly prepared meat and poultry normally the source of the bacteria. Antibiotics are created to respond like the body’s immune system in attacking a certain area of the bacteria. Knowing that all bacteria do not have the same structure could enable development of a new class of antibiotics that exploit this difference in the C. jejuni’s structure. “It could take some time for any new treatment to be developed, but now that we know for a fact that the bacteria’s structure is different, that can allow for a more effective treatment of the infection,” Egelman says.
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Researchers from the University of Virginia have shown that the widely held belief that all bacteria move by the same structures is not true. Led by Edward H. Egelman, Ph.D., Professor of Biochemistry and Molecular Genetics, the team showed that flagellar filaments from the bacteria Campylobacter jejuni have only seven protofilaments compared to the 11 found in Salmonella typhimurium. C. jejuni is one of the major causes of bacterial diarrhea, and the UVA team’s discovery could help scientists develop treatments for the disease.