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微生物里的超级恶棍:逆转录病毒 – 译学馆
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微生物里的超级恶棍:逆转录病毒

Retroviruses: Microbial Supervillains

忘掉汉斯·格鲁伯 伏地魔和让巴普蒂斯特伊曼纽尔索克吧
Forget your Hans Grubers, Lord Voldemorts, and Jean-Baptiste Emanuel Zorg — it’s
该见识见识真正的超级恶棍了
time to meet some real supervillains.
就人体而言的超级恶棍
Well, supervillains as far as the human body is concerned.
它们叫逆转录病毒它们实际上会改变宿主的DNA
They’re called retroviruses, and they actually change their host cell’s DNA.
【介绍】
[intro]
你应该很熟悉病毒 它们很小–大概比多数的细菌小一千倍
You’re probably familiar with viruses: they’re super small — roughly a thousand times smaller
而细菌本身也比你体内的多数细胞
than most bacteria, which themselves are much smaller than most of the cells in your
小得多
body.
这些微生物本质是游离的蛋白质外壳和内部的一些DNA
These microbes are essentially a floating protein shell with a little bit of DNA or
或RNA 它们用这些分子保存遗传信息
RNA inside, which are the molecules they use to store their genetic information.
这种病毒只会附着特定类型的细胞这取决于病毒的种类
The virus only attaches to certain types of cells, depending on the type of virus.
一旦它发现了合适的细胞并附着上 病毒就会把它的内容物注入细胞
Once it finds the cell it needs and latches on, the virus releases its guts into the cell,
然后利用被感染细胞的机制 制造出更多病毒
where it then uses the machinery of the cell it’s infected to make more viruses.
细胞中的制造工厂 核糖体 会读取病毒的RNA
Ribosomes in the cell, which are basically the cellular manufacturers, read the viral
并开始制造RNA对应的氨基酸
RNA and start making the amino acids the RNA says to make.
这些氨基酸成为了酶 催化合成蛋白质外壳和更多病毒DNA和RNA
Those amino acids become enzymes, which create protein shells and more viral DNA and RNA,
然后组装成更多的病毒
which then come together to form more viruses.
新的病毒会在细胞中积累直到把细胞撑爆 然后释放到
The new viruses pile up until they explode out of the cell, releasing more viruses into
宿主体内
the body.
病毒能通过这种途径飞快地传播
Viruses can use this process to spread really fast.
幸运的是 在它们吞没一切之前 我们能制造出
Luckily for us, we can create antibodies to recognize and destroy cells infected with
可以识别和破坏被感染细胞的抗体
viruses before they overwhelm everything.
但即使是最简单的病毒也会对细胞的健康造成极大的威胁
Still, even regular viruses can be pretty dangerous to the health of a cell.
但是在逆转录病毒面前普通的病毒看起来就像是一群笨拙的孩子
But, retroviruses make regular viruses look like a bunch of dumb babies.
逆转录病毒成为超级恶棍的罪魁祸首是逆转录酶
Retroviruses get their supervillain status because of an enzyme called reverse transcriptase.
逆转录酶读取病毒的RNA并将其转化DNA
Reverse transcriptase reads the virus’s RNA and turns it into DNA, which then makes
这些DNA随后混进细胞的DNA中 并连接上去
its way into the cell’s DNA and attaches itself.
一旦病毒的DNA进入了细胞DNA中 细胞就开始把这些新来的DNA和
Once the viral DNA is in the cell’s DNA, the cell just starts copying the new DNA along
自身的一起复制
with its own.
逆转录病毒DNA感染细胞后能够在激活自身前潜伏
After the retroviral DNA infects a cell, it can lie dormant for a while before it activates
一段时间
itself.
在此期间这些病毒大量复制 给细胞提供了很多
On top of this these viruses are reproduced a ton, so it provides lots of opportunities
突变的机会
for mutation.
这个过程使得免疫系统很难把它们清除掉
All of this makes it incredibly difficult for the immune system to fight them off.
我们来看一个例子:HIV
Let’s take a look at a real-world example: HIV.
HIV针对人体内一种特定的免疫细胞 名叫CD4
HIV targets a certain kind of immune cell in the human body called CD4.
这种细胞也叫辅助性T细胞
These cells are also known as helper T cells.
闯入细胞后 HIV的RNA和逆转录酶就开始制造
After breaking into the cell, HIV’s RNA and reverse transcriptase enzymes start creating
DNA链
lines of HIV DNA.
这些DNA进入CD4细胞的细胞核 然后融合到
That DNA makes its way into the CD4 cell’s nucleus, and sews itself into the cell’s
宿主细胞的DNA上
DNA.
既然成了细胞基因的一部分它们就可以开始搞破坏了
Now that it’s part of the cell’s genetic makeup, it can start wreaking havoc.
有时它们几乎会立即造成损害
Sometimes it can cause damage almost immediately.
其他时候 它可以潜伏数年之久同时在被感宿主的免疫系统中
Othertimes, it can stay dormant for years while it’s reproduced all around the infected
到处复制
host’s immune system.
这种病毒最终会让被感染的细胞丧失功能甚至杀死细胞
The virus eventually disables the cells that it infects, or sometimes even kills them.
缺乏抵抗力的免疫系统会让人体面临各种不同的威胁
Having a compromised immune system exposes the human body to all sorts of different dangers,
HIV最终发展成艾滋病一种严重并且经常会致命的情形
and HIV eventually progresses into AIDS, a serious and often fatal condition.
幸运的是 有对付逆转录病毒的疗法
Fortunately, there are treatments for retroviruses.
在HIV的案例中医生经常会给病人开混合药物 以对抗
In the case of HIV, the patient’s usually given a cocktail of drugs to fight the spread
病毒的传播
of the virus.
这些药物通常有一种或两种作用:阻止逆转录酶的激活
These drugs usually do one of two things: prevent reverse transcriptase from becoming
或者组织HIV进入细胞
active, or stop HIV from entering the cell.
但是它们不能治愈HIV–只能减缓它
But they can’t cure HIV — they can only slow it down.
虽然它们这么难打败但是逆转录病毒有可能帮助了人类的进化
Even though they’re so hard to fight, retroviruses might have helped shape human evolution — and
我们甚至可能用它们来对抗疾病
we might even be able to use them to /fight/ disease.
通过分析人类基因组并和我们已知的逆转录病毒基因组对比
By analyzing the human genome and comparing it to what we know about retroviral genomes,
研究者推测1%-8%的人类基因组区域来自
researchers estimate that somewhere between 1 and 8 percent of the human genome came from
逆转录病毒
retroviruses.
这些病毒在数百万年前感染了我们的祖先它们对DNA的改变
These viruses infected our ancestors millions of years ago, and the changes they made to
被保留了下来
their DNA stuck around.
现在 大多数病毒基因已经突变成完全不活跃的状态
These days, most of those virus genes have mutated to the point where they’re totally
不会真正影响我们的生活
inactive and don’t really affect our lives at all.
但是有一些仍与疾病有关联尤其是自身免疫病和一些癌症
But a few have been linked to diseases, especially autoimmune diseases and some cancers.
但愿了解更多这些关联的信息能够帮助研究者发明出新的疗法
Hopefully, learning more about those links will help researchers develop new treatments.
一些研究者正在研究如何利用逆转录病毒本身作为治疗手段
And some researchers are looking into how to use retroviruses /themselves/ as treatments.
因为逆转录病毒可以改变细胞的DNA 它们可以被用来导入新的基因以对抗疾病
Since retroviruses can change a cell’s DNA, they can be used to insert new genes to fight
比如某些癌症
diseases, like certain cancers.
但是这种疗法仍然有一些问题 因为逆转录病毒
There have been some problems with these treatments, though, since retroviruses can be kind of
在改变细胞基因组的时候的行为不可预测
unpredictable when it comes to changing a cell’s genome.
例如 它们可能把新基因插入另一个基因的中间
For example, they might insert the new gene right in the middle of another gene, which
这会干扰细胞中的重要过程
could interfere with important processes in the cell.
但是研究者在试图让逆转录病毒把新的基因仅仅插入到
But researchers are looking into ways to make retroviruses insert new genes only in very
特定的位点
specific spots.
所以让逆转录病毒如此危险的能力也可能让它们最终成为
So the ability that makes retroviruses so dangerous might also eventually make them
一种有力的治疗手段
a powerful treatment.
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大反派 逆转录病毒

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