Researchers create a near replica of the Hepatitis C virus
a virus-like "replicon" that can like the hepatitis C virus (hcv) produce proteins has been created in the laboratory by a team led by Charles Rice at the Washington University in St Louis, us . Till now efforts to determine just how an infection develops and how to combat it with antiviral drugs have been stalled by difficulties faced in growing hcv s in the laboratory. An estimated one per cent of the us population alone -- more than two million people -- are infected with the virus, which can persist in the body for many years. The virus often shows little or no symptoms. But over time it can damage the liver and increase the risk of cancer. Twelve years ago, researchers identified hcv as the elusive pathogen that was causing liver related diseases in some people who had received blood transfusions.
Rice says his work is based on earlier research done by Ralf Bartenschlager and colleagues at the Institute for Virology at Johanes-Gutenberg University in Mainz, Germany. Bartenschlager's team took the hcv genome apart and reassembled it into a replicon, editing out parts and adding new pieces, including an antibiotic resistance gene that can be used to select the cell clones that produce the viral proteins. To improve the efficiency of Bartenschlager's initial system, Rice rebuilt the system, looking for genetic mutations that might enable the replicon to be more productive. They found 10 mutations. "This made a big difference. It means that we have to no longer rely on cumbersome cell techniques and it also allows us to do genetic studies on a much shorter time scale," claims Rice.
The replicon will help investigators study the effects of antiviral drugs and host control mechanisms that regulate hcv replication," says Frank Chisari of the Scripps Research Institute in La Jolla, California, usa . But the replicons lack the key genes that enable the virus to infect human cells and replicate normally.
Rice's new system may also elbow its way into a highly contentious industrial arena, where biotech firms and pharmaceutical companies are battling for priority. Already, Chiron Corporation of Emeryville, California, has filed a string of lawsuits to protect its patents on hcv . Rice has begun making his replicon system available through Apath LLC, a St Louis-based company. Other groups are said to be developing their own similar replicons.
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