In 2008, something incredible happened: a man was cured of HIV.
2008年，难以置信的事情发生了：一名HIV患者被成功治愈。
In over 70 million HIV cases, that was a first and, so far, a last.
在超过七千万HIV病例中，这是第一例，目前为止也是最后一例。
We don't yet understand exactly how he was cured.
我们无法确切的知道他是如何被治好的。
We can cure people of various diseases, such as malaria and hepatitis C, so why can't we cure HIV?
我们可以治愈很多疾病，比如疟疾与丙肝，但是我们为何不能治愈HIV？
Well, first let's examine how HIV infects people and progresses into AIDS.
首先，让我们来看HIV病毒是如何感染人类以及如何发展成为艾滋病。
HIV spreads through exchanges of bodily fluids.
HIV病毒通过体液交换传播。
Unprotected sex and contaminated needles are the leading cause of transmission.
无保护的性行为和污染的针头是传播的主要原因。
It, fortunately, cannot spread through air, water, or casual contact.
幸运的是，HIV无法通过空气、水或者接触传播。
Individuals of any age, sexual orientation, gender and race can contract HIV.
任何年纪、性取向、性别和种族的个体都有可能感染HIV。
Once inside the body, HIV infects cells that are part of the immune system.
一旦进入人体，HIV病毒便开始感染免疫系统的细胞。
It particularly targets helper T cells, which help defend the body against bacterial and fungal infections.
它专门攻击辅助型T细胞，这是一种帮助人体抵抗细菌和真菌感染的细胞。
HIV is a retrovirus, which means it can write its genetic code into the genome of infected cells,
HIV是逆转录病毒，它可以将自己的基因编码写入被感染细胞的基因组，
co-opting them into making more copies of itself.
指派他们复制更多的病毒。
During the first stage of HIV infection, the virus replicates within helper T cells, destroying many of them in the process.
在HIV感染初期，病毒在辅助性T细胞中复制，在这个过程中破坏了许多T细胞。
During this stage, patients often experience flu-like symptoms, but are typically not yet in mortal danger.
在这个阶段，患者通常有类似流感的症状，但不会有生命危险。
However, for a period ranging from a few months to several years,
在几个月甚至几年的一段时期内，
during which time the patient may look and feel completely healthy,
患者可能看起来很健康，
the virus continues to replicate and destroy T cells.
但病毒持续复制，同时破坏T细胞。
When T cell counts drop too low,
当T细胞数目过低，
patients are in serious danger of contracting deadly infections that healthy immune systems can normally handle.
患者将处于致死性感染的危险中，这种感染在健康的免疫系统中是可以被抵御的。
This stage of HIV infection is known as AIDS.
HIV感染的这个阶段被称作艾滋病。
The good news is there are drugs that are highly effective at managing levels of HIV
好消息是已经有有效的药物能够控制HIV病毒水平，
and preventing T cell counts from getting low enough for the disease to progress to AIDS.
并防止T细胞数目过低，从而避免发展成为艾滋病。

With antiretroviral therapy, most HIV-positive people can expect to live long and healthy lives,
如果进行抗逆转录病毒治疗，大部分HIV阳性的病人能够继续正常生活，
and are much less likely to infect others.
而且也会减少对其他人的感染。
However, there are two major catches.
但目前有两个难点。
One is that HIV-positive patients must keep taking their drugs for the rest of their lives.
第一，HIV阳性病人在有生之年必须一直服药。
Without them, the virus can make a deadly comeback.
如果停止，HIV会恶化。
So, how do these drugs work?
那么，这些药物是如何起作用的？
The most commonly prescribed ones prevent the viral genome from being copied and incorporated into a host cell's DNA.
最常用的那些临床药物可以阻止病毒的基因复制并合并入宿主细胞DNA。
Other drugs prevent the virus from maturing or assembling, causing HIV to be unable to infect new cells in the body.
其他的药物可以阻止病毒的变异和组装，使得HIV病毒不能感染体内其他细胞。
But HIV hides out somewhere our current drugs cannot reach it: inside the DNA of healthy T cells.
但是HIV病毒会藏在目前药物无法到达的地方：健康T细胞的DNA中。
Most T cells die shortly after being infected with HIV.
大部分T细胞被HIV传染后迅速死亡。
But in a tiny percentage, the instructions for building more HIV viruses lies dormant, sometimes for years.
但是很小的一部分，被用作构建更多HIV病毒的场所，会处于休眠，有时甚至好几年。
So even if we could wipe out every HIV virus from an infected person's body,
因此，即使我们能够清除感染人体的每一个HIV病毒，
one of those T cells could activate and start spreading the virus again.
一个这样的T细胞就能激活并且重新传播病毒。
The other major catch is that not everyone in the world has access to the therapies that could save their lives.
另一个难点是，并不是世界上的所有人都能获得这些能够挽救他们生命的药物。
In Sub-Saharan Africa, which accounts for over 70% of HIV patients worldwide,
在撒哈拉以南非洲，这个地区占全球艾滋病患者的70%以上，
antiretrovirals reached only about one in three HIV-positive patients in 2012.
2012年，仅有三个HIV阳性患者接受抗逆转录病毒治疗。
There is no easy answer to this problem.
这个问题很难解决。
A mix of political, economic and cultural barriers makes effective prevention and treatment difficult.
政治、经济、文化的障碍使得有效的预防和治疗变得困难。
And even in the U.S., HIV still claims more than 10,000 lives per year.
即使是在美国，每年HIV也会夺去超过10000人的生命。
However, there is ample cause for hope.
但是依然有希望。
Researchers may be closer than ever to developing a true cure.
研究人员比以往任何时候都接近发展出真正的治疗方法。
One research approach involves using a drug to activate all cells harboring the HIV genetic information.
一项研究涉及使用一种药物激活隐含HIV遗传信息的所有细胞。
This would both destroy those cells and flush the virus out into the open, where our current drugs are effective.
这将破坏这些细胞并且将病毒暴露出来，接着我们现有的药物就可以起作用了。
Another is looking to use genetic tools to cut the HIV DNA out of cells genomes altogether.
另外一种是使用基因工具将HIV的DNA从细胞基因组剪切下来。
And while one cure out of 70 million cases may seem like terrible odds, one is immeasurably better than zero.
尽管七千万人中仅有一例治愈，但是一个总比没有好。
We now know that a cure is possible, and that may give us what we need to beat HIV for good.
我们现在清楚治疗还是有可能的，这告诉我们将需要什么去击败HIV。