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Forget your Hans Grubers, Lord Voldemorts, and Jean-Baptiste Emanuel Zorg —
忘掉汉斯·格鲁伯 伏地魔和 让巴普蒂斯特伊曼纽尔索克吧
it's time to meet some real supervillains.
该见识见识真正的超级恶棍了
Well, supervillains as far as the human body is concerned.
就人体而言的超级恶棍
They're called retroviruses, and they actually change their host cell's DNA.
它们叫逆转录病毒 它们实际上会改变宿主的DNA
You're probably familiar with viruses: they're super small — roughly a thousand times smaller than most bacteria,
你应该很熟悉病毒 它们很小 --大概比多数的细菌小一千倍
which themselves are much smaller than most of the cells in your body.
而细菌本身也比你体内的多数细胞 小得多
These microbes are essentially a floating protein shell with a little bit of DNA or RNA inside,
这些微生物本质是游离的蛋白质外壳 内部有一些DNA或RNA
which are the molecules they use to store their genetic information.
它们用这些分子保存遗传信息
The virus only attaches to certain types of cells, depending on the type of virus.
这种病毒只会附着特定类型的细胞 这取决于病毒的种类
Once it finds the cell it needs and latches on, the virus releases its guts into the cell,
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
where it then uses the machinery of the cell it's infected to make more viruses.
然后利用被感染细胞的机制 制造出更多病毒
Ribosomes in the cell, which are basically the cellular manufacturers,
细胞中的制造工厂 核糖体
read the viral RNA and start making the amino acids the RNA says to make.
会读取病毒的RNA 并开始制造RNA对应的氨基酸
Those amino acids become enzymes, which create protein shells and more viral DNA and RNA,
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
which then come together to form more viruses.
然后组装成更多的病毒
The new viruses pile up until they explode out of the cell, releasing more viruses into the body.
新的病毒会在细胞中积累 直到把细胞撑爆 然后释放到 宿主体内
Viruses can use this process to spread really fast.
病毒能通过这种途径飞快地传播
Luckily for us, we can create antibodies to recognize and destroy cells infected with viruses before they overwhelm everything.
幸运的是 在它们吞没一切之前 我们能制造出 可以识别和破坏被感染细胞的抗体
Still, even regular viruses can be pretty dangerous to the health of a cell.
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
But, retroviruses make regular viruses look like a bunch of dumb babies.
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
Retroviruses get their supervillain status because of an enzyme called reverse transcriptase.
逆转录病毒成为超级恶棍的罪魁祸首是逆转录酶
Reverse transcriptase reads the virus's RNA and turns it into DNA,
逆转录酶读取病毒的RNA并将其转化DNA
which then makes its way into the cell's DNA and attaches itself.
这些DNA随后混进细胞的DNA中 并连接上去
Once the viral DNA is in the cell's DNA, the cell just starts copying the new DNA along with its own.
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 自身的一起复制
After the retroviral DNA infects a cell, it can lie dormant for a while before it activates itself.
逆转录病毒DNA感染细胞后 能够在激活自身前潜伏 一段时间
On top of this these viruses are reproduced a ton, so it provides lots of opportunities for mutation.
在此期间这些病毒大量复制 给细胞提供了很多 突变的机会
All of this makes it incredibly difficult for the immune system to fight them off.
这个过程使得免疫系统很难把它们清除掉
Let's take a look at a real-world example: HIV.
我们来看一个例子：HIV
HIV targets a certain kind of immune cell in the human body called CD4.
HIV针对人体内一种特定的免疫细胞 名叫CD4
These cells are also known as helper T cells.
这种细胞也叫辅助性T细胞
After breaking into the cell, HIV's RNA and reverse transcriptase enzymes start creating lines of HIV DNA.
闯入细胞后 HIV的RNA和逆转录酶就开始制造 DNA链
That DNA makes its way into the CD4 cell's nucleus, and sews itself into the cell's DNA.
这些DNA进入CD4细胞的细胞核 然后融合到 宿主细胞的DNA上
Now that it's part of the cell's genetic makeup, it can start wreaking havoc.
既然成了细胞基因的一部分 它们就可以开始搞破坏了
Sometimes it can cause damage almost immediately.
有时它们几乎会立即造成损害
Othertimes, it can stay dormant for years while it's reproduced all around the infected host's immune system.
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 到处复制
The virus eventually disables the cells that it infects, or sometimes even kills them.
这种病毒最终会让被感染的细胞丧失功能 甚至杀死细胞
Having a compromised immune system exposes the human body to all sorts of different dangers,
缺乏抵抗力的免疫系统会让人体 面临各种不同的威胁
and HIV eventually progresses into AIDS, a serious and often fatal condition.
HIV最终发展成艾滋病 一种严重并且经常会致命的情形
Fortunately, there are treatments for retroviruses.
幸运的是 有对付逆转录病毒的疗法
In the case of HIV, the patient's usually given a cocktail of drugs to fight the spread of the virus.
在HIV的案例中 医生经常会给病人开混合药物 以对抗 病毒的传播
These drugs usually do one of two things:
这些药物通常有一种或两种作用：
prevent reverse transcriptase from becoming active, or stop HIV from entering the cell.
阻止逆转录酶的激活 或者组织HIV进入细胞
But they can't cure HIV — they can only slow it down.
但是它们不能治愈HIV--只能减缓它
Even though they're so hard to fight, retroviruses might have helped shape human evolution —
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
and we might even be able to use them to /fight/ disease.
我们甚至可能用它们来对抗疾病
By analyzing the human genome and comparing it to what we know about retroviral genomes,
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
researchers estimate that somewhere between 1 and 8 percent of the human genome came from retroviruses.
研究者推测1%-8%的人类基因组区域来自 逆转录病毒
These viruses infected our ancestors millions of years ago, and the changes they made to their DNA stuck around.
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 被保留了下来
These days, most of those virus genes have mutated to the point
现在 大多数病毒基因已经突变成
where they're totally inactive and don't really affect our lives at all.
完全不活跃的状态 不会真正影响我们的生活
But a few have been linked to diseases, especially autoimmune diseases and some cancers.
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
Hopefully, learning more about those links will help researchers develop new treatments.
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
And some researchers are looking into how to use retroviruses /themselves/ as 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
Since retroviruses can change a cell's DNA, they can be used to insert new genes to fight diseases, like certain cancers.
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 比如某些癌症
There have been some problems with these treatments, though,
但是这种疗法仍然有一些问题
since retroviruses can be kind of unpredictable when it comes to changing a cell's genome.
因为逆转录病毒 在改变细胞基因组的时候的行为不可预测
For example, they might insert the new gene right in the middle of another gene,
例如 它们可能把新基因插入另一个基因的中间
which could interfere with important processes in the cell.
这会干扰细胞中的重要过程
But researchers are looking into ways to make retroviruses insert new genes only in very specific spots.
但是研究者在试图让逆转录病毒把新的基因仅仅插入到 特定的位点
So the ability that makes retroviruses so dangerous might also eventually make them a powerful treatment.
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 一种有力的治疗手段
Thanks for watching this episode of SciShow, which was brought to you by our patrons on Patreon.
谢谢观看本期科学秀 这是由我们在Patreon上的赞助人 给大家带来的
If you want to help support this show, just go to patreon.com/scishow.
如果你想支持科学秀 就去patreon.com/scishow吧
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别忘了去youtube.com/scishow 订阅我们
