经济学人下载:抵抗毒瘾

Science and technology
科学技术

Combating addiction
抵抗毒瘾

Can a vaccine stop drug abuse?
有抗毒品的疫苗么？

It may be possible to vaccinate people against addictive drugs
也许通过接种疫苗帮助人们摆脱毒瘾将成为可能

THE idea of vaccinating drug addicts against their affliction is an intriguing one.
给瘾君子注射疫苗以帮助他们摆脱痛苦是一个非常有趣得想法。

In principle, it should not be too hard.
原则上，这并不难。

The immune system works, in part, by making antibodies that are specific to particular sorts of hostile molecule.
在某种程度上，免疫系统针对某些有害分子产生抗体来实现运作。

Such antibodies recognise and attach themselves to these molecules, rendering them harmless.
抗体可以识别这些分子并将自己与它们粘附在一起使得它们无害化。

Vaccines work by presenting the immune system with novel targets, so that it can learn to react to them if it comes across them again.
接种疫苗就是通过向免疫系统提供新的目标，这样当免疫系统下次遇到这些目标时就会知道如何应对。

The problem is that the molecules antibodies recognise and react to are the big ones,
问题在于抗体能够识别并作出反应的分子都是像蛋白质这样的大分子，

such as proteins, that are characteristic of bacteria, viruses and other infectious agents.
这些分子是细菌，病毒以及其他传染介质的特性。

Small molecules, such as drugs, go unnoticed.
而像药品这样的小分子却不会被注意到。

But not for much longer, if Kim Janda of the Scripps Research Institute in San Diego has his way.
但是如果来自圣地亚哥，斯克里布斯研究所的吉姆·简达的研究工作一帆风顺的话，这种情况将不会持续太久。

In a paper just published in the Journal of the American Chemical Society, Dr Janda and his colleagues suggest how a vaccine against methamphetamine, a popular street drug, might be made.
在刚刚发表在《美国化学协会期刊》上的论文中，简达博士指出一种针对甲基苯丙胺的疫苗将出现。

If their method works, it would open the possibility of vaccinating people against other drugs, too.
如果他们的方法可行，开发针对其他毒品的疫苗将成为可能。

The idea of a methamphetamine vaccine is not new.
甲基苯丙胺疫苗不算出新。

The problem is getting the immune system to pay attention to a molecule that is such a small target.
问题是让免疫系统注意到这么小的一个目标。

The way that has been tried in the past is to build the vaccine from several components.
过去所尝试过的方法是让疫苗的组成成分多样化。

First, there is a large carrier protein that forms a platform for the target.
首先，需要建立一个大型蛋白质载体以作为目标平台。

Then there is the target itself, a set of smaller molecules called haptens that are attached to the carrier.
在有了目标之后，再将一系列叫做半抗原的小分子附属在载体上。

These may either be the drug in question or some analogue of it that, for one reason or another, is reckoned to have a better chance of training the immune system.
这些半抗原既可以是毒品本身也可以是毒品的类似物质从而更好地引起免疫系统的注意。

Finally, there is a chemical cocktail called an adjuvant that helps get the immune system to pay attention to the carrier protein and the haptens.
最后，一个叫做辅助剂的化学品混合体可以帮助免疫系统注意到蛋白质载体和这些半抗原。

Dr Janda noticed that past experiments on methamphetamine vaccines had all revolved around tweaking either the carrier protein or the adjuvant,
简达博士注意到过去对于甲基苯丙胺疫苗的试验总是围绕着蛋白质载体或者辅助剂在进行，

rather than tinkering with the haptens.
而忽略了半抗原。

He thought he might be able to change that, on the basis of work he had carried out previously, trying to design a vaccine against nicotine.
他认为基于之前为设计一种尼古丁疫苗而开展的研究，他将改变这一状况。

In particular, nicotine is a highly flexible molecule.
特别是尼古丁的分子存在很高的变化性。

That makes it hard for the immune system to recognise.
这使得免疫系统难以识别他们。

To overcome this, his team on the nicotine project had to work out how to fix their haptens to the carrier protein in a way that rendered them less capable of twisting and turning, and thus made them easier for the immune system to identify.
为了克服这一问题，其尼古丁疫苗项目团队必须找到如何将半抗原固定在蛋白质载体上的方法，使得这些分子不那么容易扭曲转动，从而更容易被免疫系统识别。

In the new study, Dr Janda and his colleagues report that they have performed a similar trick with methamphetamine haptens.
在新的研究中，简达博士和他的同事们报告称他们针对甲基苯丙胺采取了相同的处理方法。

They used computer models to visualise the haptens in three dimensions and thus work out how the molecules could be rearranged such that they could not spring, twist or turn when being examined by the immune system.
他们使用电脑模型来呈现半抗原的3D图像并且解决了如何重新安排分子位置以使得其在被免疫系统检查时不会突然活动，扭曲或者转动。

In light of this information they designed six new methamphetamine-like haptens.
鉴于这些信息，他们设计了6种新的类似于甲基苯丙胺的半抗原。

Once built, they attached the new hapten molecules to carrier proteins, mixed them with adjuvant, injected the results into mice and waited.
在半抗原成形后，他们将这些新的半抗原分子附到蛋白质载体上并与辅助剂混合再注射到小鼠身上等待结果。

After several weeks they tested the mice to see if the animals'blood contained antibodies to methamphetamine.
几周后，他们对小鼠进行检查看这些动物的血液中是否含有甲基苯丙胺的抗体。

Of the six new haptens, three successfully provoked the mice to make such antibodies.
在这6种新的半抗原中有3种成功在小鼠体内产生了抗体。

As a bonus, one of those three also stimulated the production of antibodies against another widely used drug, amphetamine.
作为额外收获，其中1种还产生了另一种被广泛使用的毒品—安非他命（苯丙胺）的抗体。

That is still a long way from providing a working vaccine, but it is an important step forward.
虽然离获得一种真正奏效的疫苗还有很长一段路要走，但是这也算是向前迈出的重要一步。

And if human immune systems react in the same way to the new vaccines as murine ones do,
如果人类的免疫系统可以像鼠科动物那样对于新疫苗产生同样的反应，

the day when a drug addict might be offered vaccination rather than opprobrium will have come a little closer.
那么离瘾君子们获得疫苗而不是羞辱的那一天又近了一步。