携带许多病毒的蝙蝠为什么不生病呢?

携带许多病毒的蝙蝠为什么不生病呢?

Like Ebola virus in Africa and the Nipah virus in Asia, the new coronavirus — 2019-nCoV — appears to have originated in bats.

与非洲的埃博拉病毒和亚洲的尼帕病毒一样，新的冠状病毒——2019-nCoV——似乎起源于蝙蝠。

Chinese researchers took samples of the coronavirus from patients in Wuhan, the city in central China where the outbreak was first detected.

中国研究人员从武汉的患者身上提取了冠状病毒样本，武汉是中国中部首次发现疫情的城市。

They compared the genetic sequence of the new coronavirus — 2019-nCoV — to a library of known viruses and found a 96% match with a coronavirus found in horseshoe bats in southwest China. The findings were published in a study in Nature this week.

他们将新冠状病毒2019-nCoV的基因序列与一个已知病毒文库进行了比较，发现与中国西南部马蹄蝠中发现的一种冠状病毒有96%的匹配度。研究结果发表在本周的《自然》杂志上。

"They're too close in terms of their pure genetics to say they're not related, or that they didn't have a common ancestor," says Vineet Menachery, a virologist at the University of Texas Medical Branch at Galveston who was not affiliated with the study.

德克萨斯大学加尔维斯顿分校的病毒学家维尼特·梅纳克里说：“就纯遗传学而言，它们太接近了，不能说它们没有血缘关系，也不能说它们没有共同的祖先。”他没有参与这项研究。

Menachery and many other researchers think this new coronavirus spread from bats to humans, with a possible stop with another animal in between.

梅纳克里和许多其他研究人员认为，这种新的冠状病毒从蝙蝠传播到人类，可能会在另一种动物之间传播。

It's happened with other coronaviruses. In the case of the SARS (Severe Acute Respiratory Syndrome) outbreak, from 2002-2003. a bat coronavirus jumped to civets, a member of the mongoose family, and was sold to people as food at markets.

其他冠状病毒也是如此。在2002年至2003年爆发的非典(SARS)疫情中，一种蝙蝠冠状病毒感染了猫鼬家族的一员果子狸，并在市场上作为食物出售给人们。

The MERS (Middle East Respiratory Syndrome) outbreak, first detected in 2012. was caused by a coronavirus that jumped from bats to camels to people who maybe drank raw camel milk or ate undercooked meat.

2012年首次发现的中东呼吸综合征(MERS)疫情是由一种冠状病毒引起的，这种病毒从蝙蝠传播到骆驼，再传播到可能饮用生骆驼奶或食用未煮熟的肉类的人身上。

So why do so many infectious diseases emerge from bats?

那么，为什么有那么多传染病是从蝙蝠身上传播出来的呢?

First, bats carry a great variety of viruses — and the viruses they carry seem more likely to spread to people. Kevin Olival, vice president of research at EcoHealth Alliance, U.S.-based nonprofit, says scientists aren't completely sure why, but it may have to do with the families of viruses that some bats tend to carry. There are over 130 different kinds of viruses found in bats.

首先，蝙蝠携带的病毒种类繁多，它们携带的病毒似乎更有可能传染给人类。凯文·奥利瓦尔是美国非营利组织生态健康联盟的研究副总裁，他说，科学家们还不完全确定原因，但这可能与一些蝙蝠倾向于携带的病毒家族有关。在蝙蝠身上发现了130多种不同的病毒。

Second, bats and humans have a lot of contact. There are billions of bats and more than 1.300 different species living on every continent except Antarctica. "There's a lot of viruses we're finding in bats because there's a lot of bats out there," says Rebekah Kading, who researches emerging infectious pathogens at Colorado State University.

第二，蝙蝠和人类有很多接触。除了南极洲之外，每个大陆上都生活着数十亿只蝙蝠和1300多种不同的物种。“我们在蝙蝠体内发现了很多病毒，因为蝙蝠无处不在，”科罗拉多州立大学研究新出现传染性病原体的丽贝卡·卡丁说。

They roost in huge, crowded colonies together. Members of different bat species share caves and hollowed out trees in groups up to the millions, where viruses can pass easily between them through close contact with each other.

它们一起栖息在巨大而拥挤的群体中。不同蝙蝠物种的成员共享洞穴和被掏空的树木，群体多达数百万，在那里病毒可以通过密切接触轻易地在它们之间传播。

They have long lifespans relative to their size, and can live for more than 30 years. "So there's a long time for them to be persistently infected with the virus and shed it into the environment," Kading says. Bat viruses are shed through urine, feces and saliva. Outbreaks of Nipah virus in Bangladesh have been linked with date palm sap collected from trees that bats had licked or urinated on.

与体型相比，它们的寿命更长，可以活30年以上。卡丁说:“因此，它们很长一段时间内会持续感染病毒，并将其释放到环境中。”蝙蝠病毒通过尿液、粪便和唾液传播。孟加拉国的尼帕病毒暴发与从被蝙蝠舔过或尿过的树上采集的椰枣汁有关。

Meanwhile, you might be wondering: Why aren't the bats themselves affected by the viruses?

与此同时，你可能会想:为什么蝙蝠本身没有受到病毒的影响?

It turns out that the answer to that question has to do with the bat's status as the world's only flying mammal.

事实证明，这个问题的答案与蝙蝠作为世界上唯一会飞的哺乳动物的地位有关。

During flight, a bat's body temperature spikes to over 100 degrees Fahrenheit. Its heart rate can surge to more than 1.000 beats per minute.

在飞行中，蝙蝠的体温会飙升到超过100华氏度。它的心率可以达到每分钟1000次以上。

"For most land mammals, these are signals that would trigger death," says Linfa Wang, who studies bat viruses at Duke-NUS Medical School in Singapore. But bats live it every day.

“对大多数陆地哺乳动物来说，这些都是触发死亡的信号，”在新加坡杜克大学-新加坡国立大学医学院研究蝙蝠病毒的王林发说。但是蝙蝠每天都这样。

Wang says it seems that bats have developed special immune systems to deal with the stress of flying.

王说，蝙蝠似乎已经发展出了特殊的免疫系统来应对飞行的压力。

Their bodies make molecules that other mammals don't have, which help repair cell damage. And their systems don't overreact to infections, which keeps them from falling ill from the many viruses they carry (and also prevents conditions like diabetes and cancer).

它们的身体制造出其他哺乳动物没有的分子，帮助修复细胞损伤。而且它们的系统不会对感染产生过度反应，这使它们不会因为携带的许多病毒而生病(也能预防糖尿病和癌症等疾病)。

This shows that it's not always the virus itself but the body's response to the virus that can make us sick, explains Wang.

王解释说，这表明并不是病毒本身，而是身体对病毒的反应使我们生病。

Olival at EcoHealth Alliance says let's be clear: it's not the bats' fault that people are getting diseases. "They've just sort of coevolved with these viruses and these bugs that basically don't cause them any harm."

生态健康联盟的奥利瓦尔说，让我们明确一下：人们感染疾病不是蝙蝠的错。“它们只是在某种程度上与这些病毒和细菌共同进化，基本上不会对它们造成任何伤害。”