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If this bat were a human, she'd be in deep trouble.
如果这只蝙蝠是人类，她就糟糕了。
She's infected with several deadly viruses, including ones that cause rabies, SARS, and Ebola.
她感染了好几个致命的病毒，包括了那些会引起狂犬病、非典和埃博拉的病毒。
But while her diagnosis would be lethal for other mammals, this winged wonder is totally unfazed.
虽然她的诊断对其他哺乳动物来说是致命的，但对于这个神奇的物种来说完全没有受到影响。
In fact, she may even spend the next 30 years living as if this were totally normal -- because for bats, it is.
事实上，她甚至可能会在接下来的30年里继续活着，仿佛完全正常，因为对于蝙蝠来说，确实如此。
So what's protecting her from these dangerous infections?
所以是什么在保护着她，从而让她免受这些危险的感染呢？
To answer this question, we first need to understand the relationship between viruses and their hosts.
为了回答这个问题，我们首先需要明白病毒及其宿主之间的关联。
Every virus has evolved to infect specific species within a class of creatures.
每一种病毒都进化成感染某一纲中的特定一种。
This is why humans are unlikely to be infected by plant viruses, and why bees don't catch the flu.
这就是为什么人类不太可能被植物病毒感染，以及为什么蜜蜂不会感染流感。
However, viruses do sometimes jump across closely related species.
但是，病毒有时候会跨越密切相关的物种。
And because the new host has no established immune defenses, the unknown virus presents a potentially lethal challenge.
由于新的宿主没有建立免疫防御系统，未知名的病毒就显现出了潜在的致命挑战。
This is actually bad news for the virus as well.
这对病毒来说实际上也是个坏消息。
Their ideal host provides a steady stream of resources and comes into contact with new parties to infect -- two criteria that are best met by living hosts.
理想的宿主提供源源不断的资源和接触新宿主的机会，活宿主恰恰提供这两个机会。
All this to say that successful viruses don't typically evolve adaptations that kill their hosts
也就是说，成功的病毒通常都不会进化到杀死它们的宿主，
including the viruses that have infected our flying friend.
包括感染了我们飞行朋友的病毒。
The deadly effects of these viruses aren't caused by the pathogens directly, but rather, by their host's uncontrolled immune response.
这些病毒的致命影响并不是由病原体直接引起的，而是由它们的宿主不受控制的免疫反应。
Infections like Ebola or certain types of flu have evolved to strain the immune system of their mammalian host by sending it into overdrive.
埃博拉病毒或某些类型的感染已经进化成过度劳损哺乳动物寄主的免疫系统，使其变得超负荷。
The body sends hordes of white blood cells, antibodies and inflammatory molecules to kill the foreign invader.
身体发送成群的白细胞、抗体和炎症分子来杀死外侵者。
But if the infection has progressed to high enough levels, an assault by the immune system can lead to serious tissue damage.
但如果感染已经进化到够高的级别，免疫系统的攻击会导致自身组织的严重损伤。
In particularly virulent cases, this damage can be lethal.
在特别严重的情况下，这种损害可能致死。
And even when it's not, the site is left vulnerable to secondary infection.
即使未致死，该处也会很容易受到二次感染。
But unlike other mammals, bats have been in an evolutionary arms race with these viruses for millennia,
但与其他哺乳动物不同的是，蝙蝠一直在与这些病毒进行军备竞赛有几千年了，
and they've adapted to limit this kind of self-damage.
而且它们已经适应了限制这种自我伤害。
Their immune system has a very low inflammatory response; an adaptation likely developed alongside the other trait that sets them apart from other mammals: self-powered flight.
它们的免疫系统具有非常低的炎症反应；一种适应能力可能与其他特征并列发展的从而使它们与其他哺乳动物区分开来：自立飞行。
This energy-intensive process can raise a bat's body temperature to over 40℃.
这种能量密集型过程可以将蝙蝠的体温升高到40摄氏度以上。
Such a high metabolic rate comes at a cost; flight produces waste molecules called Reactive Oxygen Species that damage and break off fragments of DNA.
如此高的代谢率是有代价的；飞行产生称为活性氧物种的废物分子会损坏和断裂DNA的片段。
In other mammals, this loose DNA would be attacked by the immune system as a foreign invader.
在其他哺乳动动中，这个松散的DNA会像外来入侵者一样受到免疫系统的攻击。
But if bats produce these molecules as often as researchers believe, they may have evolved a dampened immune response to their own damaged DNA.
但如果蝙蝠经常产生这些分子就像研究人员想的那样，它们可能已经减弱了免疫系统的反应来损坏它们自己的DNA。
In fact, certain genes associated with sensing broken DNA and deploying inflammatory molecules are absent from the bat genome.
事实上，某些与断裂DNA相关的基因和部署炎症分子是不存在蝙蝠基因组中的。
The result is a controlled low-level inflammatory response that allows bats to coexist with the viruses in their systems.
这个结果是一个受约束的低水平炎症反应，允许蝙蝠与它们系统中的病毒共存。
Even more impressive, bats are able to host these viruses for decades without any negative health consequences.
更令人惊讶的是，蝙蝠能够携带这些病毒数十年而不会对健康造成任何负面影响。
According to a 2013 study, bats have evolved efficient repair genes to counteract the frequent DNA damage they sustain.
根据2013年的一项研究，蝙蝠已经进化出有效的修复基因来抵消它们所承受的频繁的DNA损伤。
These repair genes may also contribute to their long lives. Animal chromosomes end with a DNA sequence called a telomere.
这些修复基因可能也会延长它们的寿命。动物染色体已一个DNA序列结束的被称为端粒。
These sequences shorten over time in a process that many believe contributes to cell aging.
这些序列在一个过程中随着时间的推移而缩短许多人认为这会导致细胞老化。
But bat telomeres shorten much more slowly than their mammalian cousins -- granting them lifespans as long as 41 years.
但是蝙蝠端粒的缩短速度要比它们的哺乳动物表亲慢得多--赋予它们长达41年的寿命。
Of course, bats aren't totally invincible to disease, whether caused by bacteria, unfamiliar viruses, or even fungi.
当然了，蝙蝠并不能完全战胜所有的疾病，无论是由细菌、不熟悉的病毒，还是真菌引起的。
Bat populations have been ravaged by a fungal infection called white-nose syndrome, which can fatally disrupt hibernation and deteriorate wing tissue.
蝙蝠种群受到过真菌感染的摧残被称为白鼻综合征，就会致命地破坏冬眠系统并致命地破坏其翅膀的组织。
These conditions prevent bats from performing critical roles in their ecosystems, like helping with pollination and seed dispersal, and consuming pests and insects.
这些状况阻止蝙蝠发挥关键作用，在它们的生态系统中，例如帮助授粉和种子传播，以及食用害虫和昆虫。
To protect these animals from harm, and ourselves from infection, humans need to stop encroaching on bat habitats and ecosystems.
为了保护这些动物免受伤害，以及我们自己免受感染，人类需要停止侵占蝙蝠的栖息地和生态系统。
Hopefully, preserving these populations will allow scientists to better understand bats' unique antiviral defense systems.
希望，保护这些群体将使科学家更好地了解蝙蝠独特的抗病毒防御系统。
And maybe one day, this research will help our own viral immunity take flight.
也许有一天，这项研究将会帮助我们提高自己的病毒免疫力。
