VOA慢速英语 2007 0418a

This is the VOA Special English Health Report.

Most vaccines¹ are designed with the same goal in mind. That is, to help the 
 
body's own defense³ system prevent a disease by producing antibodies against it. Antibodies are disease-fighting proteins. The immune system produces them in reaction to viruses, bacteria and other invaders⁴.

The vaccine² tricks the body into thinking it has already successfully defeated the disease. To activate⁵ the immune system, vaccines commonly introduce the disease-causing virus or bacteria into the body. But they use weakened or killed versions.

Weakened viruses are used, for example, in vaccines against chickenpox, measles⁶, mumps⁷ and rubella. To prevent polio, the Sabin vaccine uses a weakened form of the virus; the Salk vaccine uses a killed version.

Experts say vaccines that use killed or inactivated⁸ virus can be safely given even to people with damaged immune systems.

Researchers may spend years working on a vaccine. They have still not succeeded against, for example, H.I.V., the virus that causes AIDS, or against malaria⁹, but they are trying.

And not all vaccines offer long-term protection. The tetanus vaccine is a good example. It offers protection for only about ten years. Then a person must be immunized again.

Some vaccines are made with animal material. For example, influenza¹⁰ vaccine is grown in chicken eggs. This can be a problem for people who are allergic¹¹ to eggs. Also, the process is complex.

But things could change in the future. A new study in the Journal of the American Medical Association suggests that flu vaccine could come from insect cells.

Researchers in the United States tested a flu vaccine made from caterpillar¹² cells. The study involved four hundred sixty people. There were two versions of the vaccine, one stronger than the other.

The people were not told whether they were getting the vaccine or a substitute, a placebo¹³. Here is what the scientists reported: Seven people in the placebo group caught the flu. So did two people who received the lower strength vaccine. But no one in the stronger vaccine group got the flu.

Protein Sciences, a vaccine maker¹⁴, paid for the study. The company plans to begin testing the experimental flu vaccine on a larger group in order to seek government approval.

And that's the VOA Special English Health Report, written by Caty Weaver¹⁵. For more health news, along with transcripts¹⁶ and audio files of our reports, go to voaspecialenglish.com. I'm Steve Ember.

1 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。

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 defense   

n.防御，保卫；[pl.]防务工事；辩护，答辩

参考例句：

• The accused has the right to defense.被告人有权获得辩护。
• The war has impacted the area with military and defense workers.战争使那个地区挤满了军队和防御工程人员。

4 invaders   

入侵者，侵略者，侵入物( invader的名词复数 )

参考例句：

• They prepared to repel the invaders. 他们准备赶走侵略军。
• The family has traced its ancestry to the Norman invaders. 这个家族将自己的世系追溯到诺曼征服者。

5 activate   

vt.使活动起来，使开始起作用

参考例句：

• We must activate the youth to study.我们要激励青年去学习。
• These push buttons can activate the elevator.这些按钮能启动电梯。

6 measles   

n.麻疹，风疹，包虫病，痧子

参考例句：

• The doctor is quite definite about Tom having measles.医生十分肯定汤姆得了麻疹。
• The doctor told her to watch out for symptoms of measles.医生叫她注意麻疹出现的症状。

7 mumps   

n.腮腺炎

参考例句：

• Sarah got mumps from her brother.萨拉的弟弟患腮腺炎，传染给她了。
• I was told not go near Charles. He is sickening for mumps.别人告诉我不要走近查尔斯， 他染上了流行性腮腺炎。

8 inactivated   

v.使不活泼，阻止活动( inactivate的过去式和过去分词 )

参考例句：

• Molluscicides are quickly inactivated by sunlight and adsorption to mud organic matter. 灭螺剂因阳光作用、泥土及有机物质的吸收会很快失效。 来自辞典例句
• Viruses were inactivated by BPL and the toxicity measured again. BPL对病毒进行灭活，测定残存毒力。 来自互联网

9 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。

10 influenza   

n.流行性感冒，流感

参考例句：

• They took steps to prevent the spread of influenza.他们采取措施
• Influenza is an infectious disease.流感是一种传染病。

11 allergic   

adj.过敏的，变态的

参考例句：

• Alice is allergic to the fur of cats.艾丽斯对猫的皮毛过敏。
• Many people are allergic to airborne pollutants such as pollen.许多人对空气传播的污染物过敏，比如花粉。

12 caterpillar   

n.毛虫，蝴蝶的幼虫

参考例句：

• A butterfly is produced by metamorphosis from a caterpillar.蝴蝶是由毛虫脱胎变成的。
• A caterpillar must pass through the cocoon stage to become a butterfly.毛毛虫必须经过茧的阶段才能变成蝴蝶。

13 placebo   

n.安慰剂；宽慰话

参考例句：

• The placebo has been found to work with a lot of different cases.人们已发现安慰剂能在很多不同的病例中发挥作用。
• The placebo effect refers to all the observable behaviors caused by placebo.安慰剂效应是指由安慰剂所引起的可观察的行为。

14 maker   

n.制造者，制造商

参考例句：

• He is a trouble maker，You must be distant with him.他是个捣蛋鬼，你不要跟他在一起。
• A cabinet maker must be a master craftsman.家具木工必须是技艺高超的手艺人。

15 weaver   

n.织布工；编织者

参考例句：

• She was a fast weaver and the cloth was very good.她织布织得很快，而且布的质量很好。
• The eager weaver did not notice my confusion.热心的纺织工人没有注意到我的狼狈相。

16 transcripts   

n.抄本（ transcript的名词复数 ）；转写本；文字本；副本

参考例句：

• Like mRNA, both tRNA and rRNA are transcripts of chromosomal DNA. tRNA及rRNA同mRNA一样，都是染色体DNA的转录产物。 来自辞典例句
• You can't take the transfer students'exam without your transcripts. 没有成绩证明书，你就不能参加转学考试。 来自辞典例句