从鸡蛋中培养流感疫菌

Modern technology has put men on the moon and deciphered the human genome. But when it comes to brewing up flu to make vaccines, science still turns to the incredible edible egg. Ever since the 1940s, vaccine makers have grown large batches of virus inside chicken eggs. But given that some 36,000 Americans die of flu each year, it’s remarkable that our first line of defense is still what Secretary of Health and Human Services Tommy Thompson calls “the cumbersome and archaic egg-based production.” New cell-based technologies are in the pipeline, however, and may finally get the support they need now that the United States is faced with a critical shortage of flu vaccine. Although experts disagree on whether new ways of producing vaccine could have prevented a shortage like the one happening today, there is no doubt that the existing system has serious flaws.

Each year, vaccine manufacturers place advance orders for millions of specially grown chicken eggs. Meanwhile, public-health officials monitor circulating strains of flu, and each March they recommend three strains—two influenza A strains and one B strain—for manufacturers to include in vaccines. In the late spring and summer, automated machines inject virus into eggs and later suck out the influenza-rich goop. Virus from the eggs’ innards gets killed and processed to remove egg proteins and other contaminants before being packaged into vials for fall shipment.

Why has this egg method persisted for six decades? The main reason is that it’s reliable. But even though the eggs are reliable, they have serious drawbacks. One is the long lead time needed to order the eggs. That means it’s hard to make more vaccine in a hurry, in case of a shortage or unexpected outbreak. And eggs may simply be too cumbersome to keep up with the hundreds of millions of doses required to handle the demand for flu vaccine.

What’s more, some flu strains don’t grow well in eggs. Last year, scientists were unable to include the Fujian strain in the vaccine formulation. It was a relatively new strain, and manufacturers simply couldn’t find a quick way to adapt it so that it grew well in eggs. “We knew the strain was out there,” recalls Theodore Eickhoff of the University of Colorado Health Sciences Center, “but public-health officials were left without a vaccine—and, consequently, a more severe flu season.”

Worse, the viruses that pose the greatest threat might be hardest to grow in eggs. That’s because global pandemics like the one that killed over 50 million people between 1918 and 1920 are thought to occur when a bird influenza changes in a way that lets it cross the species barrier and infect humans. Since humans haven’t encountered the new virus before, they have little protective immunity. The deadly bird flu circulating in Asia in 1997 and 1998, for example, worried public-health officials because it spread to some people who handled birds and killed them—although the bug never circulated among humans. But when scientists tried to make vaccine the old-fashioned way, the bird flu quickly killed the eggs.

1.The moon-landing is mentioned in the first paragraph to illustrate_____.

[A] technology cannot solve all of our human problems

[B] progress in vaccine research for influenza has lagged behind

[C] great achievements have been made by men in exploring the unknown

[D] the development of vaccine production methods can not be stopped

2.What step is essential to the traditional production of flu vaccine?

[A] Manufacturers implant the vaccine into ordered chicken eggs.

[B] Scientists identify the exact strain soon after a flu pandemic starts.

[C] Public health measures are taken as an important pandemic-fighting tool.

[D] Viruses are deadened and made clean before being put into vaccine use.

3.The foremost reason why the egg-based method is defective lies in_____.

[A] the complex process of vaccine production [B] its potential threat to human being

[C] the low survival rate for new flu vaccines [D] its contribution to the flu vaccine shortage

4.Which of the following is true according to the passage?

[A] Flu vaccines now mainly use egg-based technology.

[B] A bird influenza has once circulated among humans.

[C] Safety can be greatly improved with cell-culture vaccines.

[D] Modern vaccine production methods are to replace egg-based methods.

5.In the author’s view, the new vaccine production method seems to be_____.

[A] remarkable [B] criticized [C] efficient [D] accepted

答案： 1.B 2.D 3.C 4.A 5.D

核心词汇与超纲词汇

(1)decipher(v.)破译，辨认(难认、难解的东西)

(2)genome(n.)基因组，染色体组

(3)brew(v.)酿制(啤酒)，沏(茶)，煮(咖啡);~ up酝酿;(常用于进行时)(不愉快的事)即将来临

(4)cumbersome(a.)大而笨重的;繁琐的，复杂的

(5)archaic(a.)过时的，陈旧的;古代的，早期的

(6)in the pipeline在准备中; 在完成中; 在进行中; (货物)运输中; 即将送递

(7)circulate(v.)循环;传播，流传;传递，传阅(~ sth. to sb.)

(8)strain(n.)(动、植物的)系，品系，品种

(9)innards(n.)内脏，内部结构

(10)pandemic(a.)广泛流传的，普遍的，流行的;(大范围)传染病的;(n.)全国[全世界]性的流行病

(11)lead time 前置时间，指完成一个程序或作业所需要的一段时间。

全文翻译

现代技术已经把人类送上了月球，也破解了人类的基因组。但是当涉及到培养流感病毒生产疫苗时，令人难以置信的是科学家依然在使用可食用鸡蛋。自20世纪40年代以来，疫苗的生产者已经在鸡蛋里培植了大批的病毒。但是，考虑到每年有约3万6千美国人死于流感，有意思的是我们的第一防线依然是被美国健康和人类服务部部长汤米•汤普森称作为“麻烦的陈旧的鸡蛋方法的生产”。但是，新的细胞生产技术已经投入使用，并且由于美国现在面临的流感疫苗的严重短缺而可能最终得到它们所需要的支持。虽然专家就生产疫苗的新方法能否阻止现在出现的这种短缺现象无法达成共识，但是可以肯定的是现有的系统有严重的缺陷。

每一年疫苗的生产者会提前预定成百万的特别培育的鸡蛋。同时，公共健康官员监督正在流行的流感种类，并于每年3月推荐其中的三种，包括两种A型和一种B型流感，为生产者生产疫苗之用。在春末和夏季，由自动的机器将病毒注射到鸡蛋中，然后将充满流感病毒的粘性物质从中吸出。将鸡蛋内脏中的病毒杀死后加工，取出鸡蛋蛋白和其他的杂质，然而装入小瓶，用于秋季时的运输。

为什么这种鸡蛋方法持续了60年?重要原因是它可靠。但是尽管鸡蛋是可靠的，它们也有严重的缺陷。首先是订购鸡蛋所需要的前置时间很长。这意味着在突发的疫苗短缺状况下很难立刻生产更多的疫苗。要满足对流感疫苗的需求需要生产几百万的剂量，而使用鸡蛋也许跟不上这个速度。

而且一些种类的流行病毒在鸡蛋中不能很好地生长。去年，科学家没能够把福建型流感种类包括在疫苗的生产中。它是一种较新的病毒种类，生产者不能找到很快适应它的方法使它在鸡蛋中很好地生长。科罗拉多州大学健康科学中心的西奥多•艾克福回忆说，“我们知道病毒种类在那里”，但是这些公共健康官员没有疫苗，于是结果迎来了一场更严重的流感。

更糟糕的是，产生最大威胁的病毒也许是最难在鸡蛋中生长的。这是因为当禽流感改变方式跨越种族界限感染人类时，像1918年至1920年间杀死5000万人的那种全球性流行病就会爆发。由于人类在这之前没有遭遇这样的新病毒，他们的保护性免疫能力就很差。比如，1997年和1998年在亚洲流行的致命的禽流感使公共健康官员很担忧，因为它传播到一些接触禽类的人类身上并使他们死亡。虽然这种病菌还没有在人类中传播过，但当科学家试图用传统的方式生产疫苗时，禽流感迅速杀死了鸡蛋。