Vaccines：A new health food
GETTING two for the price of one is always a good bargain. And according to a paper in this week’s Proceedings of the National Academy of Sciences, that is what Tomonori Nochi of the University of Tokyo and his colleagues have done. Using genetic engineering, they have overcome two of the limitations of vaccines. One is that they are heat-sensitive and thus have to be transported along a “cold chain” of refrigerators to the clinics where they are used. The other is that, although they stimulate immune responses inside the body, they often fail to extend that protection to the outside, where it might prevent bacteria and viruses getting inside in the first place.In this context, the outside is not the skin: that is dry and hostile to germs. It is the damp and welcoming surface of places such as the lung and the gut that are at risk. Although these are casually called internal, technically they are not. Any nasties in the gut or lungs have to cross the walls of those organs before they can multiply inside the body.
Dr Nochi’s genetic engineering involved growing the vaccine in rice. To prove the principle, he chose cholera, but it should work with other vaccines as well. With cholera, the immune response is induced by what is known as the cholera toxin B-subunit. This is a protein, and Dr Nochi took the gene that encodes it and inserted that gene into the genome of rice. Next to the B-subunit gene itself, he inserted a second piece of DNA called a promoter. This, as its name suggests, promotes activity in an adjacent gene. Promoters themselves are activated by other molecules, and whether they are switched on or not depends on whether the cell they are in provides the necessary stimulation. In this case Dr Nochi picked a promoter that is active in the tissue of rice grains.
It was then just a question of growing the rice and feeding the resulting grains to some experimental mice to find out what would happen. The first thing that happened was that the grains protected the B-subunit from being broken down in the stomach, thus overcoming one of the regular bugbears of protein-based drugs: that they cannot be given by mouth, because they will be digested. This is a problem with today’s cholera vaccine which is indeed taken by mouth and therefore affords poor protection. When the B-subunits got to the intestines they did exactly what Dr Nochi hoped and induced the production of antibodies and the secretion of those antibodies into the mucous coating of the intestinal wall. Dr Nochi’s mice really were protected. When he fed them cholera toxin, they did not get sick.
On top of all this, he got as good a response with rice that had been stored at room temperature for 18 months as he did when he used fresh grains. For a vaccine against a disease that is found predominantly in poor countries—places that tend to lack refrigerators and have only intermittent power to run those that do exist—that is an enormous advance. If Dr Nochi’s finding can be translated into a product that is safe and effective for people, it will be a big boost to the health of the world’s poor.
考研詞匯：
overcome[ˌəuvəˈkʌm]
v.戰(zhàn)勝，克服
[真題例句]If we do not confront and overcome these internal fears and doubts, if we protect ourselves too much, then we cease to grow.[1995年閱讀2]
[例句精譯] 如果我們不能去正視并克服這些內(nèi)在的恐懼和疑慮，如果我們過于自我保護，那么我們就會停止成長。
hostile[ˈhɔstail]
a.敵對的，敵方的，敵意的
[真題例句]Stratford-on-Avon, as we all know, has only one industry—William Shakespeare—but there are two distinctly separate and increasingly hostile branches.[2006年閱讀2]
[例句精譯] 正如我們所知，埃文河上的斯特福特就只有一個行業(yè)——威廉·莎士比亞——但是卻有兩個界限清楚并各懷敵意的分支部門。
induce[inˈdju:s]
v.①引誘，勸使;②引起，導致;③感應
[真題例句]Indeed, the mere presence of a grape in the other chamber (without an actual monkey to eat it) was enough to induce (②) sullen behaviour in a female capuchin.[2005年閱讀1]
[例句精譯] 事實上，一個籠舍里葡萄的存在(就算是沒有猴子在吃)，就足以引起另一只猴子憤憤不平了。
adjacent[əˈdʒeisənt]
a.(to)鄰近的，毗連的
mucous[ˈmju:kəs]
a.黏液的, 黏液似的
enormous[iˈnɔ:məs]
a.巨大的，龐大的
[真題例句]Of course, the use of the Internet isnt the only way to defeat poverty.And the Internet is not the only tool we have.But it has enormous potential.[2001年閱讀2]
[例句精譯] 當然，使用互聯(lián)網(wǎng)不是惟一消滅貧困的方法?；ヂ?lián)網(wǎng)也不是我們所擁有的惟一工具，但它卻有巨大的潛力。
GETTING two for the price of one is always a good bargain. And according to a paper in this week’s Proceedings of the National Academy of Sciences, that is what Tomonori Nochi of the University of Tokyo and his colleagues have done. Using genetic engineering, they have overcome two of the limitations of vaccines. One is that they are heat-sensitive and thus have to be transported along a “cold chain” of refrigerators to the clinics where they are used. The other is that, although they stimulate immune responses inside the body, they often fail to extend that protection to the outside, where it might prevent bacteria and viruses getting inside in the first place.In this context, the outside is not the skin: that is dry and hostile to germs. It is the damp and welcoming surface of places such as the lung and the gut that are at risk. Although these are casually called internal, technically they are not. Any nasties in the gut or lungs have to cross the walls of those organs before they can multiply inside the body.
Dr Nochi’s genetic engineering involved growing the vaccine in rice. To prove the principle, he chose cholera, but it should work with other vaccines as well. With cholera, the immune response is induced by what is known as the cholera toxin B-subunit. This is a protein, and Dr Nochi took the gene that encodes it and inserted that gene into the genome of rice. Next to the B-subunit gene itself, he inserted a second piece of DNA called a promoter. This, as its name suggests, promotes activity in an adjacent gene. Promoters themselves are activated by other molecules, and whether they are switched on or not depends on whether the cell they are in provides the necessary stimulation. In this case Dr Nochi picked a promoter that is active in the tissue of rice grains.
It was then just a question of growing the rice and feeding the resulting grains to some experimental mice to find out what would happen. The first thing that happened was that the grains protected the B-subunit from being broken down in the stomach, thus overcoming one of the regular bugbears of protein-based drugs: that they cannot be given by mouth, because they will be digested. This is a problem with today’s cholera vaccine which is indeed taken by mouth and therefore affords poor protection. When the B-subunits got to the intestines they did exactly what Dr Nochi hoped and induced the production of antibodies and the secretion of those antibodies into the mucous coating of the intestinal wall. Dr Nochi’s mice really were protected. When he fed them cholera toxin, they did not get sick.
On top of all this, he got as good a response with rice that had been stored at room temperature for 18 months as he did when he used fresh grains. For a vaccine against a disease that is found predominantly in poor countries—places that tend to lack refrigerators and have only intermittent power to run those that do exist—that is an enormous advance. If Dr Nochi’s finding can be translated into a product that is safe and effective for people, it will be a big boost to the health of the world’s poor.
考研詞匯：
overcome[ˌəuvəˈkʌm]
v.戰(zhàn)勝，克服
[真題例句]If we do not confront and overcome these internal fears and doubts, if we protect ourselves too much, then we cease to grow.[1995年閱讀2]
[例句精譯] 如果我們不能去正視并克服這些內(nèi)在的恐懼和疑慮，如果我們過于自我保護，那么我們就會停止成長。
hostile[ˈhɔstail]
a.敵對的，敵方的，敵意的
[真題例句]Stratford-on-Avon, as we all know, has only one industry—William Shakespeare—but there are two distinctly separate and increasingly hostile branches.[2006年閱讀2]
[例句精譯] 正如我們所知，埃文河上的斯特福特就只有一個行業(yè)——威廉·莎士比亞——但是卻有兩個界限清楚并各懷敵意的分支部門。
induce[inˈdju:s]
v.①引誘，勸使;②引起，導致;③感應
[真題例句]Indeed, the mere presence of a grape in the other chamber (without an actual monkey to eat it) was enough to induce (②) sullen behaviour in a female capuchin.[2005年閱讀1]
[例句精譯] 事實上，一個籠舍里葡萄的存在(就算是沒有猴子在吃)，就足以引起另一只猴子憤憤不平了。
adjacent[əˈdʒeisənt]
a.(to)鄰近的，毗連的
mucous[ˈmju:kəs]
a.黏液的, 黏液似的
enormous[iˈnɔ:məs]
a.巨大的，龐大的
[真題例句]Of course, the use of the Internet isnt the only way to defeat poverty.And the Internet is not the only tool we have.But it has enormous potential.[2001年閱讀2]
[例句精譯] 當然，使用互聯(lián)網(wǎng)不是惟一消滅貧困的方法?；ヂ?lián)網(wǎng)也不是我們所擁有的惟一工具，但它卻有巨大的潛力。