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  • If this bat were a human, she'd be in deep trouble.

    如果這隻蝙蝠是人,那她的麻煩可就大了。

  • She's infected with several deadly viruses, including ones that cause rabies, SARS, and Ebola.

    她被數種致命病毒感染,其中包括造成狂犬病、SARS,及伊波拉的病毒。

  • But while her diagnosis would be lethal for other mammals, this winged wonder is totally unfazed.

    雖然她的診斷結果對其他哺乳類動物而言會相當致命,但這隻有翅膀的奇蹟生物卻完全不受影響。

  • In fact, she may even spend the next 30 years living as if this were totally normalbecause for bats, it is.

    事實上,她可能會把這個狀況當作家常便飯一樣,繼續過著接下來 30 年的生活—因為對蝙蝠而言,這的確沒什麼大不了的。

  • So what's protecting her from these dangerous infections?

    所以,究竟是什麼原因讓她能不受這些危險的感染影響?

  • To answer this question, we first need to understand the relationship between viruses and their hosts.

    要回答這個問題,我們首先要了解病毒和其宿主之間的關係。

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

    每種病毒都已經演化成會感染某一綱當中的特定物種。

  • This is why humans are unlikely to be infected by plant viruses, and why bees don't catch the flu.

    這就是人類為什麼不太可能被植物病毒感染,以及蜜蜂為什麼不會得流感的原因。

  • However, viruses do sometimes jump across closely related species.

    然而,病毒的確有時會跳躍傳播到近親物種上。

  • And because the new host has no established immune defenses, the unknown virus presents a potentially lethal challenge.

    由於新的宿主尚未建立起免疫防禦,未知的病毒便有可能帶來致命的危害。

  • This is actually bad news for the virus as well.

    而這對病毒來說其實也是個壞消息。

  • Their ideal host provides a steady stream of resources and comes into contact with new parties to infecttwo criteria that are best met by living hosts.

    理想的宿主會持續提供穩定而源源不絕的資源,並且會去接觸新的感染對象—而活體宿主最好都能達到這兩項標準。

  • All this to say that successful viruses don't typically evolve adaptations that kill their hostsincluding the viruses that have infected our flying friend.

    言下之意就是,成功的病毒通常不會演化出會造成宿主死亡的適應性—包括感染我們那些蝙蝠朋友的病毒亦是如此。

  • The deadly effects of these viruses aren't caused by the pathogens directly, but rather, by their host's uncontrolled immune response.

    這些病毒的致命作用並非由病原體直接造成,而是由其宿主控制不了的免疫反應所造成。

  • Infections like Ebola or certain types of flu have evolved to strain the immune system of their mammalian host by sending it into overdrive.

    像伊波拉或某些類型的感冒等感染,都已經演化成會讓哺乳類宿主的免疫系統過度操勞而負荷過重。

  • The body sends hordes of white blood cells, antibodies and inflammatory molecules to kill the foreign invader.

    身體會派出大量白血球細胞、抗體,以及促使發炎的分子,藉此殺死外來的入侵者。

  • But if the infection has progressed to high enough levels, an assault by the immune system can lead to serious tissue damage.

    然而如果情況已經發展為相當嚴重的感染,免疫系統的攻擊則可能會對生理組織造成嚴重損傷。

  • In particularly virulent cases, this damage can be lethal.

    在特別劇烈的情況下,這種損傷可能會危及性命。

  • And even when it's not, the site is left vulnerable to secondary infection.

    就算不致命,受損傷處也很容易受到二度感染。

  • But unlike other mammals, bats have been in an evolutionary arms race with these viruses for millennia, and they've adapted to limit this kind of self-damage.

    但和其他哺乳類不同的是,數千年來,蝙蝠都一直在和這些病毒進行演化競賽,而牠們已經適應成能夠限制住這種自我損傷。

  • 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.

    牠們的免疫系統發炎反應非常低,而這種適應性可能是和讓牠們與其他哺乳類有所不同的另一項特性一起發展出來的:自供能式飛行。

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

    這個需要大量能量的過程,會讓蝙蝠的體溫提高到攝氏 40 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.

    然而要達到這麼高的新陳代謝率是有代價的;飛行會產生出一種稱為活性氧類的廢棄分子,它們會破壞並將 DNA 的一些片段切斷。

  • In other mammals, this loose DNA would be attacked by the immune system as a foreign invader.

    換作其他哺乳類,這種鬆散的 DNA會被免疫系統視為外來入侵者而發動攻擊。

  • But if bats produce these molecules as often as researchers believe, they may have evolved a dampened immune response to their own damaged DNA.

    但如果蝙蝠產生這些分子的頻率有研究者所相信的那麼頻繁,牠們可能已經演化成會對自己的受損 DNA 只產生較輕的免疫反應。

  • In fact, certain genes associated with sensing broken DNA and deploying inflammatory molecules are absent from the bat genome.

    事實上,某些和感測受損 DNA 及部署促炎分子有關的基因都不在蝙蝠的基因組中。

  • The result is a controlled low-level inflammatory response that allows bats to coexist with the viruses in their systems.

    結果就是調節得當的低度發炎反應,讓蝙蝠能夠和其系統中的病毒共存。

  • Even more impressive, bats are able to host these viruses for decades without any negative health consequences.

    更讓人印象深刻的是,蝙蝠能當這些病毒的宿主數十年而不會在健康上有任何負面影響。

  • According to a 2013 study, bats have evolved efficient repair genes o counteract the frequent DNA damage they sustain.

    一篇 2013 年的研究指出,蝙蝠已經演化出有效的修復基因,以對抗牠們經常受到的 DNA 損傷。

  • These repair genes may also contribute to their long lives.

    這些修復基因可能也是牠們壽命較長的原因之一。

  • Animal chromosomes end with a DNA sequence called a telomere.

    動物染色體的末端有著叫做「端粒」的 DNA 序列。

  • These sequences shorten over time in a process that many believe contributes to cell aging.

    這類序列會隨時間縮短,而許多人相信這個過程和細胞老化有關。

  • But bat telomeres shorten much more slowly than their mammalian cousinsgranting them lifespans as long as 41 years.

    但蝙蝠的端粒縮短速度比其他親源相近的哺乳類要慢很多—讓牠們的壽命能長達 41 年。

  • Of course, bats aren't totally invincible to disease, whether caused by bacteria, unfamiliar viruses, or even fungi.

    當然,蝙蝠並不是完全不怕疾病,能讓牠們生病的有細菌、陌生病毒,甚至是黴菌。

  • Bat populations have been ravaged by a fungal infection called white-nose syndrome, which can fatally disrupt hibernation and deteriorate wing tissue.

    蝙蝠的數量曾經因為一種叫做白鼻症的黴菌感染而銳減,而這種疾病會打斷冬眠、讓翅膀組織退化,最後致命。

  • These conditions prevent bats from performing critical roles in their ecosystems, like helping with pollination and seed dispersal, and consuming pests and insects.

    這些疾病讓蝙蝠無法扮演牠們在生態系統中的重要角色,比如協助授粉、傳播種子,以及吃掉危害作物的動物和昆蟲。

  • To protect these animals from harm, and ourselves from infection, humans need to stop encroaching on bat habitats and ecosystems.

    為了保護這些動物不受傷害以及保護我們自己不受感染,人類必須要停止侵犯蝙蝠的棲息地和生態系統。

  • Hopefully, preserving these populations will allow scientists to better understand bats' unique antiviral defense systems.

    希望做好蝙蝠族群的保育,能讓科學家更了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,這些研究也能協助我們自己對抗病毒的免疫能力一飛衝天。

  • From plant pollination to pest control, bats are an essential part of our ecosystems.

    從為植物授粉到控制害蟲數量,蝙蝠是我們生態系中不可或缺的一份子。

  • So why are they known as nature's villains? Find out more about these misunderstood animals with this video.

    既然如此,為什麼牠會被人當作自然界的反派呢?從以下的影片中瞭解這種被誤解的動物的更多資訊吧。

If this bat were a human, she'd be in deep trouble.

如果這隻蝙蝠是人,那她的麻煩可就大了。

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B2 中高級 中文 TED-Ed 蝙蝠 病毒 宿主 免疫 哺乳動物

為什麼蝙蝠不會生病?了解蝙蝠獨特的抗病毒防禦系統 (Why bats don't get sick - Arinjay Banerjee)

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    林宜悉 發佈於 2021 年 10 月 24 日
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