2007年VOA标准英语-Inexpensive Vaccines Against Diseases May be So

By Steve Mort
Orlando, Florida
16 January 2007
 
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A U.S. scientist is developing a method to produce inexpensive vaccines against disease. Professor Henry Daniell, from the University of Central Florida, has found a way to genetically 3 engineer plants to make large amounts of certain vaccines.

The drugs, taken orally rather than by injection, would be much cheaper than traditional vaccines -- making them ideal for use in poor countries. And the U.S. government hopes the research will boost the availability of medicines to fight bio-terror threats like anthrax.

At this lab, scientists are working to revolutionize the way people around the world are vaccinated 4 for a range of diseases.

 
Professor Henry Daniell
Professor Henry Daniell has devised a way to produce oral vaccines at a fraction of the usual cost, making them affordable 5 in developing countries. "One third of the world population, two billion people, earn less than two dollars a day. And a $26,000 to $40,000 treatment is unimaginable for that population. So even though treatments are available they're beyond their reach. And now, through oral delivery, it is possible for the world, no matter where they live, to get this treatment in an affordable manner."

Scientists first inject plants, like tobacco, lettuce 6 or carrots, with vaccine 1 genes 7.

They are then planted in a greenhouse before being crushed and put into capsules to be taken by patients. The method skips a number of traditional processes involved in producing the therapeutic 8 proteins needed to make vaccines -- cutting the price of the final product.

Professor Daniell explains. “By doing this you completely eliminate all the other costs associated with the therapeutic proteins. But the major unanticipated advantage of this was our ability to cure certain autoimmune diseases which has never been done before. And so that was an added benefit which came in relation to reducing the cost of the therapeutic proteins".

And these oral vaccines, if approved, would be much easier to mass produce.

It's estimated just one acre of tobacco plants, for example, could produce enough anthrax vaccine to inoculate 9 everyone in the United States.

Professor Daniell says the possibilities are wide-ranging. "We have now developed this system for several vaccines -- for the bio-terrorism vaccines like anthrax and for plague, but for other important diseases in developing countries -- waterborne pathogens like cholera 10, amebiasis and also viruses like rotavirus. All of these vaccines have already been developed. We are also in the process of developing vaccines for malaria 11 and tuberculosis 12".

The U.S. government, including the National Institutes of Health, has provided $3 million of funding for the research. Tests in mice have been successful and it's believed there are fewer side effects than with traditional vaccines.

The next step, Professor Daniell describes, “is to move this to human clinical trials. And in the case of bioterrorism vaccines, these are on fast track approval. And so in those cases we have found additional support in the U.S. It is extremely expensive -- it costs $300-400 million to do these clinical trials".

Professor Daniell says he decided 13 to work on cheap vaccines after witnessing the impact of disease in his native India.

It's hoped the research will lead to treatments for further illnesses, including diabetes 14 and hepatitis, as well as other bioterrorism agents.