The research, which could lead to the development of future treatments, was published today in the journal PLoS ONE. The study was led by Ohio University scientist Erin Murphy and doctoral student William Broach, with contributions from University of Nevada, Las Vegas and University of Texas at Austin researchers.
Bright spots among intestinal cells show where the shigella bacteria were able to replicate, indicating their ability to cause disease. Credit: Erin Murphy/Ohio University
When the disease-causing bacterium Shigella invades a human host, environmental conditions there, such as changes in temperature or pH, stimulate a genetic expression pathway within the bacterium that allows it to survive and cause disease. Central to this genetic pathway are two proteins, VirF and VirB. VirF functions to increase production of VirB which, in turn, promotes the production of factors that increases the bacterium's virulence, or ability to cause illness in its host.
"It's like a domino effect," said Murphy, assistant professor of bacteriology in the Ohio University Heritage College of Osteopathic Medicine.
Murphy and Broach's new study, however, suggests that production of VirB can be controlled independently of VirF. It also shows that the VirF-independent regulation is mediated by a specific small RNA, a special type of molecule whose job is to control the production of particular targets. This is the first study to demonstrate that transcription of virB is regulated by any factor other than VirF, Murphy explained.
The research not only reveals the intricate level of gene expression the bacteria employ to survive in the human body, but potentially could lead to new treatments. Currently, antibiotics are prescribed to patients with the disease.
"These findings are feeding into the basic understanding of this gene expression so that future researchers can work to disrupt it," Broach said. "The more we know about it, the more targets we have to disrupt it and to possibly develop targeted antibiotic treatments."
For those living in developing countries, where access to clean drinking water can be scarce, an improved medical treatment for shigellosis could mean the difference between life and death.
"In the United States, if we get severe diarrhea we can go to the store and get Gatorade," Murphy said. "But if you're already starving to begin with because you don't have access to good food and clean water, then you get shigellosis on top of that—and you don't have good water to rehydrate yourself—that's when the deaths happen."
The disease, which is transmitted person to person or through contaminated food or water sources, has an infectious dose of just 10 organisms, meaning as few as 10 organisms can cause disease in a healthy person. This infectious dose is exceedingly low compared to other bacteria that require tens of thousands of organisms to cause disease.
While it is often thought to be a third-world problem, shigellosis causes a reported 14,000 cases in the United States each year. The Centers for Disease Control suggests that the actual number may be 20 times higher, as mild cases often aren't reported or diagnosed.
"In the United States it's probably even more underreported than in developing countries because of access to healthy, clean drinking water," Murphy said. "If you're a healthy individual and you've got access to clean drinking water, chances are you're going to get severe diarrhea, but you're not going to die."
The research was funded by the National Institutes of Health, the Ohio University Research Committee and the Ohio University Heritage College of Osteopathic Medicine.
The collaborators on the PLoS ONE paper are University of Nevada, Las Vegas scientists Nicholas Egan and Helen Wing and University of Texas at Austin researcher Shelley Payne.
The PLoS ONE paper can be accessed online: http://dx.plos.org/10.1371/journal.pone.0038592
Andrea Gibson | EurekAlert!
Further reports about: > Las Vegas > Medicine > Nevada > Ohio > Osteopathic > Osteopathic Medicine > PLoS One > Shigella > VirF-independent regulation > antibiotic treatments > bacterium's virulence > clean drinking water > developing countries > diarrheal disease shigellosis > drinking water > environmental conditions > severe diarrhea > water source
Tiny Helpers that Clean Cells
14.08.2018 | Albert-Ludwigs-Universität Freiburg im Breisgau
Light-controlled molecules: Scientists develop new recycling strategy
14.08.2018 | Humboldt-Universität zu Berlin
Researchers from TU Graz and their industry partners have unveiled a world first: the prototype of a robot-controlled, high-speed combined charging system (CCS) for electric vehicles that enables series charging of cars in various parking positions.
Global demand for electric vehicles is forecast to rise sharply: by 2025, the number of new vehicle registrations is expected to reach 25 million per year....
Proteins must be folded correctly to fulfill their molecular functions in cells. Molecular assistants called chaperones help proteins exploit their inbuilt folding potential and reach the correct three-dimensional structure. Researchers at the Max Planck Institute of Biochemistry (MPIB) have demonstrated that actin, the most abundant protein in higher developed cells, does not have the inbuilt potential to fold and instead requires special assistance to fold into its active state. The chaperone TRiC uses a previously undescribed mechanism to perform actin folding. The study was recently published in the journal Cell.
Actin is the most abundant protein in highly developed cells and has diverse functions in processes like cell stabilization, cell division and muscle...
Scientists have discovered that the electrical resistance of a copper-oxide compound depends on the magnetic field in a very unusual way -- a finding that could help direct the search for materials that can perfectly conduct electricity at room temperatur
What happens when really powerful magnets--capable of producing magnetic fields nearly two million times stronger than Earth's--are applied to materials that...
The quality of materials often depends on the manufacturing process. In casting and welding, for example, the rate at which melts solidify and the resulting microstructure of the alloy is important. With metallic foams as well, it depends on exactly how the foaming process takes place. To understand these processes fully requires fast sensing capability. The fastest 3D tomographic images to date have now been achieved at the BESSY II X-ray source operated by the Helmholtz-Zentrum Berlin.
Dr. Francisco Garcia-Moreno and his team have designed a turntable that rotates ultra-stably about its axis at a constant rotational speed. This really depends...
If certain signaling cascades are misregulated, diseases like cancer, obesity and diabetes may occur. A mechanism recently discovered by scientists at the Leibniz- Forschungsinstitut für Molekulare Pharmakologie (FMP) in Berlin and at the University of Geneva has a crucial influence on such signaling cascades and may be an important key for the future development of therapies against these diseases. The results of the study have just been published in the prestigious scientific journal 'Molecular Cell'.
Cell growth and cell differentiation as well as the release and efficacy of hormones such as insulin depend on the presence of lipids. Lipids are small...
08.08.2018 | Event News
27.07.2018 | Event News
25.07.2018 | Event News
14.08.2018 | Medical Engineering
14.08.2018 | Life Sciences
14.08.2018 | Life Sciences