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36 反口蹄疫的疫苗
VOICE ONE:
(Start at 1'00") American scientists are developing new vaccine medicines against Foot-and-Mouth Disease. They hope to stop serious infections like the one now affecting animals in Europe. Currently, Foot-and-Mouth Disease vaccines are made from a virus that causes the disease. Such vaccines use a killed or weakened virus.
However, experts say the current vaccines are difficult to use. They say such vaccines offer only short-term protection against Foot-and-Mouth disease. The United States Department of Agriculture is working to develop more powerful and longer-lasting vaccines. The Department operates the Plum Island Animal Disease Center. It is near the coast of Long Island, New York. The center is the only American laboratory with enough £±) security to safely study the virus.
VOICE TWO:
Peter Mason directs the Foot-and-Mouth Disease research team at Plum Island. He says the team is using genetic engineering to develop several new kinds of vaccines. One new kind of vaccine uses genetic material from the virus. It is injected into the animal. The D-N-A £²) molecules cause the animal to make proteins similar to those produced by the virus. This helps the animal to develop resistance to the disease.
Another method involves pieces of genetic material from the Foot-and-Mouth Disease virus. Scientists put this D-N-A material into other harmless viruses. When injected into a healthy animal, the changed viruses can cause resistance to fight Foot-and-Mouth and other diseases.
VOICE ONE:
Mister Mason says both experimental vaccines would be effective for controlling infections among large numbers of animals. He says the vaccines help build up natural resistance quickly and safely among animals near infected areas.
The American scientist says tests with the new vaccines are hopeful. However, the vaccines probably will not be ready to be used for several years.
(THEME)
VOICE TWO:
This SCIENCE IN THE NEWS program was written and produced by George Grow. This is Sarah Long.
VOICE ONE:
And this is Bob Doughty. Join us again next week for more news about science in Special English on the Voice of America.
(1) security [ si5kjuEriti ] n.安全
(2) molecules [ 5mClikju:l, 5mEu- ]n.[化]分子, 些微
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