Hepatitis A spreads through the consumption of fecal particles from an infected person (in pollution-contaminated food or water, for example), but hepatitis C is generally transmitted only by direct contact with infected blood. Hepatitis A produces fever, nausea and abdominal pain that can last for weeks, but rarely lead to death; hepatitis C, by contrast, often spends decades quietly damaging the liver, until a victim’s only hope for survival is an organ transplant.
According to researchers at the University of Texas Medical Branch at Galveston (UTMB), though, these two otherwise unrelated liver viruses have one important thing in common: a trick for avoiding destruction by the immune system. Both dodge immune attacks by attacking the same protein — an essential link in a chain of molecular signals that triggers antiviral responses.
"With 30,000-plus proteins in the cell, it’s really remarkable that these two very different viruses have chosen to strike at the same one," said Dr. Stanley Lemon, director of UTMB’s Institute for Human Infections and Immunity and National Institutes of Health-funded Hepatitis C Research Center. Lemon is senior author of a paper on the research appearing online this week in the Proceedings of the National Academy of Sciences. "This identifies the protein — called MAVS, for mitochondrial antiviral signaling protein — as extremely important for the survival of any virus in the liver."
MAVS proteins project from tiny structures called mitochondria, which are found in large numbers in each liver cell. When specialized receptor molecules detect viruses in the cell, they dock with the MAVS proteins, thereby triggering a sequence of signals ending with the production of interferon beta— a potent inhibitor of virus replication. Recent research has shown that hepatitis C generates a protein called NS3/4A that chops up MAVS, interfering with immune signaling and possibly providing the cover the virus needs to survive so long in the liver. Now, Lemon and his group have demonstrated that hepatitis A does the same thing with a different protein, known as 3ABC.
"Hepatitis A never manages to establish a long-term infection like hepatitis C even though it also destroys MAVS," Lemon said. "This suggests that the degradation of this cell protein is not the main reason that hepatitis C becomes persistent. These results thus provide a new perspective on the chronicity of hepatitis C, which is a highly relevant virus clinically."
Hepatitis C has received far more research attention than hepatitis A in recent years, according to Lemon, largely because of hepatitis C’s chronic nature and the lack of a vaccine against it. But while better sanitation has driven a decline in hepatitis A cases in the United States, Lemon said, "It’s a significant risk for many people traveling overseas, because they fail to receive the vaccine." Hepatitis A has also been the cause of large food-borne outbreaks in the U.S. in recent years, including one in Pennsylvania that caused three deaths in otherwise healthy adults.
Jim Kelly | EurekAlert!
New technology offers fast peptide synthesis
28.02.2017 | Massachusetts Institute of Technology
Biofuel produced by microalgae
28.02.2017 | Tokyo Institute of Technology
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded after a glide flight with an Airbus A320 in ditching on the Hudson River. All 155 people on board were saved.
On January 15, 2009, Chesley B. Sullenberger was celebrated world-wide: after the two engines had failed due to bird strike, he and his flight crew succeeded...
Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...
The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.
The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...
Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...
13.02.2017 | Event News
10.02.2017 | Event News
09.02.2017 | Event News
28.02.2017 | Life Sciences
28.02.2017 | Power and Electrical Engineering
28.02.2017 | Information Technology