VOA标准英语2011--New Malaria Vaccine Passes Safety Test

New Malaria¹ Vaccine² Passes Safety Test

The fight against malaria may have taken a promising³ step forward with the latest tests of a new kind of vaccine, which aims to keep people healthy and prevent the infection from spreading.
Most malaria vaccines⁴ under development work by including genetically⁵ engineered versions of just a handful of the thousands of proteins of the Plasmodium parasite⁶. Those modified proteins are designed to trigger an immune response to Plasmodium, after it’s passed into the host’s bloodstream by the bite of an infected mosquito.
In contrast, says researcher Robert A. Seder of the U.S. National Institute of Allergy⁷ and Infectious Diseases, this new vaccine includes a deactivated⁸ version of the entire parasite.
"So instead of picking out one or two or three genes," he says, "you have the potential for what we call breadth - generating an immune response that would be broad rather than narrower. And so that would be a good thing."
Plasmodium goes through many stages in its life cycle. To make this vaccine, scientists use the parasite at the stage - called the sporozoite - when it's ready to infect new hosts. They remove the sporozoite from the mosquito's salivary⁹ glands¹⁰ and then subject it to radiation.
That weakens it, so it can't cause malaria symptoms, and can't be transmitted via mosquito to another person, either.
This concept has been known since the 1960s, but Seder says there were practical obstacles that prevented the development of a malaria vaccine.
"The major breakthrough here was that my collaborator¹¹, Stephen Hoffman at [vaccine company] Sanaria, developed a method where he could isolate¹² the sporozoites and purify them so that they could administer it as a vaccine to humans. And no one thought that that was possible," he explained.
And no one knew if the weakened sporozoites would jump-start the immune system to protect against malaria.
To find out, researchers used human volunteers. The vaccine was injected into their skin with a needle, to simulate the bite of a mosquito. From a safety standpoint, the results were good - there were only relatively¹³ minor¹⁴ side effects. But a vaccine must be safe and effective, and this one just wasn't very effective. Only two out of 44 volunteers who got the vaccine were protected when bitten by malaria-infected mosquitoes.
To find out why, the researchers then switched to laboratory animals, and Seder says they concluded that the problem was the way the vaccine was administered.
"Had [Hoffman] given [the vaccinations] in the vein¹⁶, intravenously, directly in the blood, rather than through the skin, he would have gotten much higher immune responses."
That would be unusual for a vaccine, which is typically given by mouth or as a skin or muscle injection. It also might complicate¹⁷ mass vaccination¹⁵ programs, if the vaccine goes into general use.
Cost is also an issue, but researcher Seder says it's too soon to know how the vaccine will be priced - assuming it is effective.
The next stage of human testing - using intravenous administration - is due to start in October.

1 malaria   

n.疟疾

参考例句：

• He had frequent attacks of malaria.他常患疟疾。
• Malaria is a kind of serious malady.疟疾是一种严重的疾病。

2 vaccine   

n.牛痘苗，疫苗；adj.牛痘的，疫苗的

参考例句：

• The polio vaccine has saved millions of lives.脊髓灰质炎疫苗挽救了数以百万计的生命。
• She takes a vaccine against influenza every fall.她每年秋季接种流感疫苗。

3 promising   

adj.有希望的，有前途的

参考例句：

• The results of the experiments are very promising.实验的结果充满了希望。
• We're trying to bring along one or two promising young swimmers.我们正设法培养出一两名有前途的年轻游泳选手。

4 vaccines   

疫苗，痘苗( vaccine的名词复数 )

参考例句：

• His team are at the forefront of scientific research into vaccines. 他的小组处于疫苗科研的最前沿。
• The vaccines were kept cool in refrigerators. 疫苗放在冰箱中冷藏。

5 genetically   

adv.遗传上

参考例句：

• All the bees in the colony are genetically related. 同一群体的蜜蜂都有亲缘关系。
• Genetically modified foods have already arrived on American dinner tables. 经基因改造加工过的食物已端上了美国人的餐桌。 来自英汉非文学 - 生命科学 - 基因与食物

6 parasite   

n.寄生虫；寄生菌；食客

参考例句：

• The lazy man was a parasite on his family.那懒汉是家里的寄生虫。
• I don't want to be a parasite.I must earn my own way in life.我不想做寄生虫，我要自己养活自己。

7 allergy   

n.(因食物、药物等而引起的)过敏症

参考例句：

• He developed an allergy to pollen.他对花粉过敏。
• The patient had an allergy to penicillin.该患者对青霉素过敏。

8 deactivated   

v.解除动员( deactivate的过去式和过去分词 )；使无效；复员；使不活动

参考例句：

• \"The brain can be deactivated. It can be yours to command.\" “大脑计算机可以被停止。如果你下达命令的话。” 来自互联网
• He successfully deactivated a nuclear reactor in a laboratory before meltdown. 他成功停用一个核反应堆在实验室之前崩溃。 来自互联网

9 salivary   

adj. 唾液的

参考例句：

• Small doses depress salivary and bronchial secretion and sweating. 小剂量可抑制唾液分泌、支气管分泌及出汗。
• The five pairs of salivary glands open into the mouth. 有五对唾液腺通向口腔。

10 glands   

n.腺( gland的名词复数 )

参考例句：

• a snake's poison glands 蛇的毒腺
• the sebaceous glands in the skin 皮脂腺

11 collaborator   

n.合作者，协作者

参考例句：

• I need a collaborator to help me. 我需要个人跟我合作，帮我的忙。
• His collaborator, Hooke, was of a different opinion. 他的合作者霍克持有不同的看法。

12 isolate   

vt.使孤立，隔离

参考例句：

• Do not isolate yourself from others.不要把自己孤立起来。
• We should never isolate ourselves from the masses.我们永远不能脱离群众。

13 relatively   

adv.比较...地，相对地

参考例句：

• The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
• The operation was relatively painless.手术相对来说不痛。

14 minor   

adj.较小(少)的，较次要的；n.辅修学科；vi.辅修

参考例句：

• The young actor was given a minor part in the new play.年轻的男演员在这出新戏里被分派担任一个小角色。
• I gave him a minor share of my wealth.我把小部分财产给了他。

15 vaccination   

n.接种疫苗，种痘

参考例句：

• Vaccination is a preventive against smallpox.种痘是预防天花的方法。
• Doctors suggest getting a tetanus vaccination every ten years.医生建议每十年注射一次破伤风疫苗。

16 vein   

n.血管，静脉；叶脉，纹理；情绪；vt.使成脉络

参考例句：

• The girl is not in the vein for singing today.那女孩今天没有心情唱歌。
• The doctor injects glucose into the patient's vein.医生把葡萄糖注射入病人的静脉。

17 complicate   

vt.使复杂化，使混乱，使难懂

参考例句：

• There is no need to complicate matters.没有必要使问题复杂化。
• These events will greatly complicate the situation.这些事件将使局势变得极其复杂。