She's infected with several deadly viruses,

她感染了幾種致命的病毒。

including ones that cause rabies, SARS, and Ebola.

包括引起狂犬病、SARS和埃博拉病毒的。

But while her diagnosis would be lethal for other mammals,

但雖然她的診斷對其他哺乳動物來說是致命的。

this winged wonder is totally unfazed.

這個長著翅膀的奇蹟完全不為所動。

In fact, she may even spend the next 30 years living

事實上，她甚至可能在接下來的30年裡

as if this were totally normal– because for bats, it is.

好像這很正常一樣 因為對蝙蝠來說，這很正常。

So what's protecting her from these dangerous infections?

那麼，是什麼在保護她免受這些危險的感染呢？

To answer this question, we first need to understand

要回答這個問題，我們首先要了解以下內容

the relationship between viruses and their hosts.

病毒與其宿主之間的關係；

Every virus has evolved to infect specific species within a class of creatures.

每一種病毒都是為了感染一類生物中的特定物種而進化的。

This is why humans are unlikely to be infected by plant viruses,

這就是為什麼人類不太可能被植物病毒感染的原因。

and why bees don't catch the flu.

以及為什麼蜜蜂不會感染流感。

However, viruses do sometimes jump across closely related species

然而，病毒有時會跨越密切相關的物種進行跳躍性傳播

And because the new host has no established immune defenses,

而且因為新的宿主沒有建立免疫防禦系統。

the unknown virus presents a potentially lethal challenge.

不明病毒是一個潛在的致命挑戰。

This is actually bad news for the virus as well.

這對病毒來說其實也是個壞消息。

Their ideal host provides a steady stream of resources

他們的理想主機提供了穩定的資源流

and comes into contact with new parties to infect—

並與新的黨派接觸，以感染。

two criteria that are best met by living hosts.

兩個標準，活著的宿主是最符合的。

All this to say that successful viruses

所有這一切都說明，成功的病毒

don't typically evolve adaptations that kill their hosts—

通常不會進化出殺死宿主的適應性----。

including the viruses that have infected our flying friend.

包括我們的飛行朋友所感染的病毒。

The deadly effects of these viruses aren't caused by the pathogens directly,

這些病毒的致命影響並不是由病原體直接造成的。

but rather, by their host's uncontrolled immune response.

而是由其宿主不受控制的免疫反應。

Infections like Ebola or certain types of flu have evolved

像埃博拉或某些類型的流感這樣的傳染病已經進化到了。

to strain the immune system of their mammalian host

使其哺乳動物宿主的免疫系統受到影響。

by sending it into overdrive.

通過將其送入超速狀態。

The body sends hordes of white blood cells,

身體會派出大批的白血球。

antibodies and inflammatory molecules to kill the foreign invader.

抗體和發炎分子來殺死外來入侵者。

But if the infection has progressed to high enough levels,

但如果感染已經發展到足夠高的程度。

an assault by the immune system can lead to serious tissue damage.

免疫系統的攻擊會導致嚴重的組織損傷。

In particularly virulent cases, this damage can be lethal.

在毒性特別強的情況下，這種損害可能是致命的。

And even when it's not,

即使是沒有。

the site is left vulnerable to secondary infection.

該部位容易發生繼發感染。

But unlike other mammals,

但與其他哺乳動物不同。

bats have been in an evolutionary arms race with these viruses for millennia,

蝙蝠與這些病毒進行了數千年的進化軍備競賽。

and they've adapted to limit this kind of self-damage.

而他們已經適應了限制這種自我傷害。

Their immune system has a very low inflammatory response;

他們的免疫系統的發炎反應很低。

an adaptation likely developed alongside the other trait

適應症

that sets them apart from other mammals: self-powered flight.

使它們與其他哺乳動物不同的是：自我驅動飛行。

This energy-intensive process can raise a bat's body temperature to over 40ºC.

這個耗能的過程可以將蝙蝠的體溫提高到40℃以上。

Such a high metabolic rate comes at a cost;

如此高的新陳代謝率是有代價的。

flight produces waste molecules called Reactive Oxygen Species

飛行會產生被稱為活性氧物種的廢物分子。

that damage and break off fragments of DNA.

破壞和斷裂的DNA片段。

In other mammals, this loose DNA

在其他哺乳動物中，這種鬆散的DNA

would be attacked by the immune system as a foreign invader.

會作為外來入侵者被免疫系統攻擊。

But if bats produce these molecules as often as researchers believe,

但如果蝙蝠像研究人員認為的那樣經常產生這些分子。

they may have evolved a dampened immune response

他們可能已經進化出了一種減弱的免疫反應。

to their own damaged DNA.

到自己受損的DNA。

In fact, certain genes associated with sensing broken DNA

事實上，某些與感知斷裂DNA相關的基因。

and deploying inflammatory molecules are absent from the bat genome.

和部署發炎分子的蝙蝠基因組中沒有。

The result is a controlled low-level inflammatory response

其結果是一個可控的低水平發炎反應。

that allows bats to coexist with the viruses in their systems.

使得蝙蝠能與系統中的病毒共存。

Even more impressive,

更讓人印象深刻。

bats are able to host these viruses for decades

蝙蝠能夠將這些病毒寄生幾十年

without any negative health consequences.

而不會對健康造成任何不利影響。

According to a 2013 study, bats have evolved efficient repair genes

根據2013年的一項研究，蝙蝠已經進化出高效的修復基因。

to counteract the frequent DNA damage they sustain.

以抵消它們經常受到的DNA損傷。

These repair genes may also contribute to their long lives.

這些修復基因可能也是它們長壽的原因。

Animal chromosomes end with a DNA sequence called a telomere.

動物的染色體末端有一個DNA序列，稱為端粒。

These sequences shorten over time in a process

在這個過程中，這些序列會隨著時間的推移而縮短。

that many believe contributes to cell aging.

許多人認為會導致細胞老化。

But bat telomeres shorten much more slowly than their mammalian cousins—

但蝙蝠端粒的縮短比哺乳動物的表親要慢得多。

granting them lifespans as long as 41 years.

賦予他們長達41年的壽命。

Of course, bats aren't totally invincible to disease,

當然，蝙蝠也不是完全無敵於疾病的。

whether caused by bacteria, unfamiliar viruses, or even fungi.

不管是由細菌、陌生病毒，甚至是真菌引起的。

Bat populations have been ravaged by a fungal infection

蝙蝠的數量已經被一種真菌感染蹂躪了

called white-nose syndrome,

稱為白鼻綜合症。

which can fatally disrupt hibernation and deteriorate wing tissue.

它能致命地破壞冬眠，使翅膀組織惡化。

These conditions prevent bats from performing critical roles

這些條件使蝙蝠無法發揮關鍵作用

in their ecosystems, like helping with pollination and seed dispersal,

在它們的生態系統中，比如幫助授粉和種子散播。

and consuming pests and insects.

並消耗害蟲和昆蟲。

To protect these animals from harm, and ourselves from infection,

為了保護這些動物不受傷害，也為了保護我們自己不受感染。

humans need to stop encroaching on bat habitats and ecosystems.

人類需要停止侵犯蝙蝠的棲息地和生態系統。

Hopefully, preserving these populations

希望能保護這些種群

will allow scientists to better understand bats' unique antiviral defense systems.

將使科學家更好地瞭解蝙蝠獨特的抗病毒防禦系統。

And maybe one day, this research will help our own viral immunity take flight.

也許有一天，這項研究會幫助我們自己的病毒免疫力騰飛。