蝙蝠为何不得新冠？

Bats can harbor many viruses that are potentially deadly to humans, including those behind SARS, Ebola and possibly SARS-CoV-2, the virus that causes COVID-19. 

蝙蝠可以携带许多对人类有潜在致命性的病毒，包括非典病毒、埃博拉病毒以及可能导致新冠的SARS- cov -2病毒。

Now scientists have identified key ways in which bats can harbor these dangerous germs while apparently suffering no ill effects from them, which may reveal ways to deal with these contagions in humans.

现在，科学家们已经确定了蝙蝠藏匿这些危险细菌的关键途径，而这些细菌显然对它们没有任何不良影响，这可能会揭示如何应对这些传染病在人类身上的传染。

Roughly 75% of the emerging infectious diseases humans face are zoonotic, or come from animals, according to the EcoHealth Alliance, an environmental health nonprofit group in New York. 

据纽约非营利环保组织生态健康联盟称，人类面临的新出现传染病中，约75%是人畜共患的，或者只来自动物。

In the past 20 years, researchers have discovered that bats host some of the most lethal emerging infectious diseases -- including those behind maladies such as Nipah, Hendra, Marburg and MERS -- yet the animals only rarely display clinical symptoms from such contagions.

在过去20年里，研究人员发现，蝙蝠体内含有一些最致命的新出现传染病——包括导致尼帕、亨德拉、马尔堡和中东呼吸综合征等疾病的那些疾病——但这些动物很少表现出这种传染的临床症状。

"When we look at bats in Southeast Asian caves, we find 5% to 10% of them are infected with coronaviruses. That's incredibly high," said disease ecologist Peter Daszak, president of the EcoHealth Alliance. 

“当我们观察东南亚洞穴里的蝙蝠时，我们发现5%到10%的蝙蝠感染了冠状病毒。这是难以置信的高，”疾病生态学家彼得·达扎克说道，他是生态健康联盟的主席。

"If you look at birds and West Nile virus, 1 in 1,000 are infected during peak season. It seems certain that bats as a group can survive a high burden of coronaviruses and other infections. Why is that?"

“如果你看看鸟类和西尼罗病毒，在高峰季节，每1000只中就有1只鸟被感染。似乎可以肯定的是，蝙蝠作为一个群体可以在冠状病毒和其他感染的高负荷下生存。这是为什么呢?”

One clue to this mystery was revealed in 2016 when virologist Lin-Fa Wang at Duke-National University of Singapore Medical School and his colleagues discovered that all known bat genomes completely lost the genes encoding molecules known as AIM2-like receptors.

2016年，新加坡杜克国立大学医学院的病毒学家王林发和他的同事发现，所有已知的蝙蝠基因组完全失去了编码分子(即像aim2样受体)的基因。

In humans, these immune proteins detect the DNA of hostile germs within cells and can trigger a cascade of events leading to inflammation and cell death.

在人类体内，这些免疫蛋白可以检测细胞内有害细菌的DNA，从而触发一系列事件，导致炎症和细胞死亡。

In the new study, Wang and his colleagues introduced the genes for human AIM2-like receptors into bat kidney and immune cells grown in lab dishes. 

在这项新的研究中，王林和他的同事们将人类类似aim2受体的基因导入蝙蝠肾脏和在实验室培养皿中生长的免疫细胞中。

This resulted in a clustering of proteins in the cells that usually mark the onset of inflammation.

而这导致了细胞中蛋白质的聚集，通常标志着炎症的开始。

However, installing AIM2-like receptors in bat cells did not restore other known inflammatory responses, such as activation of the enzyme caspase-1, which plays a central role in mobilizing immune defenses. 

然而，在蝙蝠细胞中安装类似于aim2的受体并不能恢复其他已知的炎症反应，例如活化半胱天冬酶-1，而半胱天冬酶-1在动员免疫防御中起核心作用。

In black fruit bats (Pteropus alecto), the scientists found that caspase-1 possessed alterations that likely blunted its activity.

在黑果蝠身上，科学家们发现半胱天冬酶-1具有可能减弱其活性的改变。

The researchers also discovered that in black fruit bats, the cave nectar bat (Eonycteris spelaea), and the vesper bat David's myotis (Myotis davidii), a protein called interleukin 1 beta that is activated by caspase-1 in humans possessed modifications that made it less active in response to greater caspase-1 activity.

研究人员还发现，在黑果蝠、洞穴花蜜蝙蝠和大卫夜蝠中，一种被半胱天冬酶-1激活的白介素1-贝塔蛋白，在对半胱天冬酶-1活性增强做出反应时，其活性降低。

All in all, these new findings revealed bats evolved strategies to tamp down their inflammatory responses at multiple levels, some of which might have evolved independently several times. 

总而言之，这些新发现揭示了蝙蝠进化出的策略，在多个层面上抑制炎症反应，其中一些可能已经独立进化了好几次。

This in turn likely helps bats tolerate potentially lethal viruses. 

这反过来可能有助于蝙蝠耐受潜在的致命病毒。

Although the absence of AIM2-like receptors might prove dangerous in some as-yet-unknown way to bats, presumably such a risk is more than offset by avoiding the harm from an overactive immune response to germs, Wang noted.

尽管缺乏类似于aim2的感受器可能会以某种未知的方式证明对蝙蝠是危险的，但据推测，避免对细菌过度活跃的免疫反应所造成的伤害，会大大抵消这种危险，王林提醒道。

Why might bats suppress inflammation? 

为什么蝙蝠能抑制炎症?

As the only flying mammal, bats are under constant metabolic stresses that land mammals do not endure, Wang said.

作为唯一会飞的哺乳动物，蝙蝠承受着陆地哺乳动物无法承受的持续代谢压力，王林说。

 "Imagine doing a 100-yard dash every night all night long, or imagine lifting your body weight -- 150 pounds, 200 pounds -- into the air all night long," said Daszak, who did not take part in this research. 

“想象一下，每晚整晚跑100码，或者整晚把自己的体重——150磅、200磅——举到空中，”达扎克说，他没有参与这项研究。

"That huge amount of stress creates breakdown products, a normal inflammatory response to which would not be sustainable."

“巨大的压力会产生分解产物，这是一种不可持续的正常炎症反应。”

Suppressing inflammation might explain not only how bats can safely harbor lethal viruses, but also why they live unusually long. 

抑制炎症可能不仅可以解释蝙蝠如何安全地携带致命病毒，还可以解释为什么它们活得异常长久。

"Small mammals like rodents usually only live 12 to 15 months even if they are not eaten by predators, but some bats of the same size live 40 to 50 years," Daszak said. 

“像啮齿动物这样的小型哺乳动物即使没有被捕食者吃掉，通常也只能活12到15个月，但是一些同样大小的蝙蝠可以活40到50年，”达扎克说。

"Maybe dampening of the inflammation response in bats impacts their longevity."

“也许抑制蝙蝠的炎症反应会影响它们的寿命。”

Over-inflammation plays an important role in many human diseases, "especially those associated with aged patients," Wang said. 

过度炎症在许多人类疾病中扮演着重要的角色，“尤其是那些与老年患者有关的疾病，”王林说。

"If we can learn the lessons from bats and apply some of them to human clinical interventions, it will be definitely novel and they will hopefully have less side effects." 

“如果我们能从蝙蝠身上吸取经验，并将其中一些应用于人类临床干预，这绝对是一项创新，而且有望减少副作用。”

For instance, "dampening inflammation can be one of the strategies to avoid severe disease in COVID-19 patients," he added.

例如，他补充说，“抑制炎症可以是避免新冠患者出现严重疾病的策略之一。”

问题

文中提到蝙蝠最长可以活到多少岁？

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