VOA标准英语2013--Discovery Could Lead to New Drugs to Block Deadly Viruses（在线收听）

Discovery Could Lead to New Drugs to Block Deadly Viruses

Viruses are strange things. Though there is some scientific question about whether viruses are alive or not, they do have a basic genetic structure that allows them to be biologically active. But they don't have the built-in reproductive capacity of bacteria -- tiny, living organisms which, once they have infected a human host, can make copies of themselves using their own DNA. 

John Connor, a virologist at Boston University in Massachusetts, explains that in order for viruses to reproduce and become a disease threat, they must first hijack the genetic machinery of a living cell:

“They’re parasites," said Connor. "They get inside our cells and use a lot of our machinery in order to make extra copies of themselves. And so that poses a really delicate question of how do you destroy the virus without getting yourself.”

Connor and his colleagues screened thousands of chemical compounds, looking for ones that showed strong antiviral activity. 

They identified several small molecules that interfere with the replication of a class of pathogens known as NNS viruses, which cause the deadly Marburg and Ebola infections, as well as measles and mumps.

Once they have invaded a host cell, NNS viruses use their own genetic molecule -- known as RNA -- to hijack the host cell's DNA and force it to make copies of the virus.

The most effective compounds discovered by the Boston researchers shut down that replication process -- at least in cell-culture experiments -- by limiting the viruses' RNA production.

The compounds do not thwart all viruses -- they have no effect, for example, on HIV, the virus that causes AIDS -- because of differences in the way viral pathogens enter and commandeer cells.

Just as antibiotics are effective against many bacterial illnesses, Connor says he hopes this discovery leads to the development of broad-spectrum antiviral drugs to treat a variety of currently incurable viral infections.

“Basically, one of the things my lab is interested in is trying to find 'monkey wrenches' [disruptive agents] to throw into viral replication machinery so it doesn’t work anymore," said Connor. "And the idea there is, if we find good ways of keeping viruses from doing their basic replication, we can ideally develop a new drug to treat these viruses.”

An article by Boston University’s John Connor and colleagues on the discovery of compounds to combat Ebola, Marburg and other viral infections is published in the journal Chemistry and Biology.