病毒和細菌對人有益的10個方面(上)

Viruses We Carried Out Of Africa Helped Us Survive

10.優勝劣汰，古老病毒們有奇功

Thanks to the science of viral molecular genetics, we now know quite a bit about the bugs that infected us along our evolutionary path, and we have found that these hitchhikers have done quite a bit to help us along the way. For example, it was the evolutionary pressure they placed upon our immune system that made it as robust as it is today. Additionally, viruses may have played a role in the loss of specific receptors that we once possessed on the surface of our cells that infectious agents could latch onto and use to cause disease. By ridding the human body of this source of disease, viruses created a safer environment for themselves, benefiting everybody involved.

隨着病毒分子遺傳學的進步，我們才知道原來有那麼多寄生蟲在影響着人類進化。準確地說，這些把人類當順風車的寄生蟲在人類遷徙進化的歷程中幫了不少忙。首先，這些外來微生物寄居在人體內，使人體產生一定排斥反應，從而形成一種迫使人類進化的推動力，正是在這種作用下，我們纔有了今天這樣強大的免疫系統。另外，在人體細胞表面有一些可以和細菌等微生物結合的特定受體，這些細菌和受體結合發生複雜的反應，往往會導致人體受損生病。因此這些黏附在細胞表面的受體，大大增加了人體患病的概率。不過寄生在人體內的病毒可以清理掉許多細菌的"內應"，使人體擺脫這些疾病的干擾。抵擋住其他外來者的入侵，不僅自己的生存環境更加安全，人體也是受益良多吶。

But they may have also played a role in ensuring that, among competing hominid species, it was Homo sapiens that came out on top. While our species was developing, disease and parasites encouraged genetic diversity and weeded out the unfit. Once the first Homo sapiens left the continent, they brought their infectious agencies and parasites with them. If you've read about North American and European smallpox, you know how this goes. While it wouldn't have been the only factor, viral parasites would spread to other hominids like Homo neanderthalensis (Neanderthals), who wouldn't have had any previous exposure to the new bugs and possessed a nasal structure that was less efficient at filtering air and keeping new viruses at bay. They would have devastated other hominid species, because the bugs were primed to live in similar environments, but the hominids were not primed to receive them. Models have shown that if Neanderthals had a mortality rate only 2 percent higher than humans, it would have been sufficient to cause their extinction after 1,000 years of competition. While disease was doubtless not the only factor, it would have certainly played a large models of human disease evolution claim that they mainly evolved during the Neolithic era, after man moved out of Africa and populations increased, so there is some evidence of this selective viral pressure. Many of these early viruses have even been so successful that their genes have literally become a part of our DNA. For example, the human genome has been found to contain genes from the borna virus that were gained about 40 million years ago. In fact, scientists have isolated about 100,000 elements of human DNA that have come from viruses, mostly within what is called our "junk DNA." The viruses that make up the majority of our junk DNA are called endogenous retroviruses, and they are so much a part of us that a scientist recently brought one "back to life" and even infected hamsters and cats with it.

除此之外，這些病毒，寄生蟲還發揮了另一項非常重要的作用。在遠古猿人時期，猿人爲了生存要和其他物種競爭資源。正是它們，幫助猿人進化成智人，登上食物鏈的最頂端。在人類發展中，疾病使得人類遺傳基因多樣化以便更加適應環境的改變，幫助剔除不適應大自然的弱小個體。當第一批智人離開原先居住的大陸時，這些傳染性的病毒、寄生蟲、細菌也跟着出發，散播到世界各地。微生物的擴散曾給人類帶來災難性的打擊，其中北美洲和歐洲的天花病毒大爆發影響最大，是人類抗擊病毒歷史當中最爲沉重的一課。尼安德特人的滅絕也和病毒、細菌傳播有關，尼安德特人原本生活在歐洲，隨着其他原人的進入，他們隨身攜帶的病毒性寄生蟲也傳播開來。一方面穴居的尼安德特人從未接觸過這些外來物種，另一方面他們已經適應北歐的寒冷氣候，鼻樑寬大，因此不能充分過濾空氣中的外來微生物，因而這些微生物足以使他們致命。儘管尼人的滅絕還受其他因素影響，但病毒入侵這一點不容忽視。疾病是促進人類進化的一大驅動力。隨着人類離開非洲大陸，人口不斷擴增，進入新石器時代，疾病與人類發展的關係更加密切。研究發現，一些人的染色體中含有博納病毒的基因序列，而這段基因是在四千萬年前和人類本身遺傳物質融合的。這表明許多古老的病毒通過逆轉錄將自己的基因嵌入到人類的DNA序列當中，這些對人體本身運作毫無用處的基因片段被稱爲"垃圾DNA"，而這種病毒被稱爲逆轉錄病毒。科學家們從垃圾DNA中提取出一萬對基因片段，經過加工處理使其重新具備合成蛋白質的能力，隨後再植入到實驗倉鼠和貓的遺傳信息中。驚人的是，這些休眠數十萬年的病毒活力依舊，又開始在小動物的體內肆虐了。

rn-Day Medical Uses Of Leeches And Maggots

9.當代醫學妙用水蛭、蛆

For thousands of years, the European leech (Hirudo medicinalis) was used in medicine for bloodletting purposes, treating a wide range of disorders from hemorrhoids to ear infections. The practice goes so far back in time that an Egyptian painting from 1500 B.C. depicts their use. While some nations have never stopped using them, the practice fell out of favor in the Western world with the knowledge of bacteria and subsequent focus on the germ theory for medical treatment.

數千年以來，歐洲水蛭一直被用作放血術的實用藥材，從痔瘡到中耳炎各種病症，用途廣泛。歐洲水蛭的具體醫療用法可以從公元前1500年前的埃及壁畫中窺見一斑。但後來隨着人們對細菌的瞭解逐漸深入，開始應用微生物理論來解決醫療問題，便不再使用水蛭了。

In the 1970s and 1980s, though, leeches made a comeback. Cosmetic and reconstructive surgeons found that they were an effective method for draining blood from swollen faces, black eyes, limbs, and digits. They are also helpful for reattaching small body parts like ears and flaps of skin, because they draw away blood that could clot and interrupt the healing process. Leeches have saved people from amputations and may even relieve the pain of osteoarthritis. Even veterinarians sometimes use ots, on the other hand, are nature's clean-up crew. They're great for eating away dead or infected flesh, revealing the healthy tissue below in a process called debridement. They have also been found to be an effective treatment for ulcers, gangrene, skin cancer, and burns, among other ots and leeches, as gross as they may be, are so effective that the FDA classified them as the first "live medical items" in 2010, paving the way for an entire industry called biotherapy. An organization called Biotherapeutics Education and Research Foundation (BTERF) has even sprung up to raise awareness of the new uses for these old critters, and there are several companies that sell them.

然而，在上世紀七十年代到八十年， 這種水蛭又重新登上醫學舞臺。當時的外科整容行業發現用歐洲水蛭將黑眼圈、大腿、手指、腫脹的臉裏的淤血吸出來效果非常明顯，除此之外，水蛭還可以促進血液流動，抑制傷口癒合以及將皮瓣組織重新連接起來。蛆，這種無頭幼蟲專吃各種腐爛或受病毒感染的屍體。醫療中常用它們清理腐爛的傷口，驅除異物，在治療潰瘍、燒傷、皮膚癌等許多方面效果都非常顯著。這種技術就叫做清創術。許多人看到這種白色不停蠕動的無頭蟲感到很心塞，事實上，它們可是大自然的清理工呢。儘管水蛭、蛆這些蠕動的軟體動物讓人覺得心塞無比，但它們的實用價值實在是高，在2010年被美國食品藥品管理局選爲首推活藥材。可以說是它們創造了一個新興領域——生物醫學療法。由此也應運而生許多機構和公司開始推廣這種新的醫療手段，並在市場上銷售歐洲水蛭和無頭幼蟲。

sites And Our Immune Systems May Have Co-Evolved To Protect Us From Allergies

8.爲了抗過敏，我們的免疫系統和寄生蟲實現了共同進化

Researchers studying the effects of gastrointestinal parasites have come up with an astonishing theory: After parasites first colonized our gastrointestinal systems, they evolved over millions of years the ability to suppress our immune systems. At the same time, our own bodies evolved to partially compensate for the effect.

在研究了胃腸道中寄生蟲對人類的影響後，研究人員提出了一個驚人的理論。他們認爲，從寄生蟲入侵我們的胃腸道系統至今，爲了抑制我們的免疫系統，它們一直在不斷地進化着。與此同時，爲了抵消這樣的影響，我們的身體也在不斷進化着。

The astonishing part, and what this means for human health, is that once parasites and harmless microorganisms present in water and soil have been largely removed from their natural environment inside of us in developed nations through the use of modern medicine, our immune systems actually overcompensate for their loss, leading to allergies and even increased chances for asthma and eczema. This "old friends" hypothesis (sometimes referred to as the "hygiene hypothesis," though it's actually more of a complementary theory) has gained more support in recent years as we identify new ways microorganisms have helped us survive over the eons. Clinical trials have been conducted using worms to test against multiple sclerosis, IBD, and main proponent of the old friends hypothesis is Graham A.W. Rook of University College London. He first proposed it in 2003, and since then, it has also been proposed as a possible cause of some forms of stress and people have taken the old friends hypothesis to its ultimate logical conclusion that if removing our parasites from society has led to health problems, we should put them back. In 2008, University of Wisconsin professor of neurology John Fleming conducted a clinical study in which he infected multiple sclerosis patients with parasitic worms to test their effectiveness against the disease. Over a period of three months, patients who had an average of 6.6 active lesions around their brain's nerve cells were reduced to an average of two. When the trial was over, the number of lesions shot back up to 5.8 within two months. In earlier trials, the parasites appeared to have positive effects upon ulcerative colitis and Crohn's disease as site therapy is still in the experimental phases, however, and probably has negative effects that outweigh the positive ones. As of now, the FDA has classified the worms as biological products that cannot be sold until proven safe. Only one species, Trichuris suis, has been approved for testing under Investigational New Drug (IND) status.

對人體健康來說，最讓人震驚的莫過於，一旦用現代藥物將水和土壤中的寄生蟲和微生物從人體內他們的生存環境中移除，我們的免疫系統實際上會因填補這種缺失而導致過敏，哮喘和溼疹發作的可能性也隨之增加。新技術的應用，使得我們能夠辨別出那些千百年來幫助我們的微生物。儘管還停留在基礎階段，"故友假設"（也稱爲衛生健康假設）也於近年來受到了日益廣泛的支持。目前，人們已經在臨牀試驗中對蠕蟲進行了抗綜合硬化症、炎症性腸病和過敏的測試。這項"舊友假設"的主要提出者是來自倫敦大學學院的格雷厄姆A.W.路客。他在2003年第一次提出這一理論，此後，醫學界認爲，該理論可以解釋某些緊張和抑鬱症的成因。有些人在"故友理論"這個問題上走了極端，他們認爲，如果把寄生蟲從人體中移除會導致健康問題，那麼我們就得把他們接回來。2008年，來自威斯康辛大學的神經學教授約翰·弗萊明進行了一項實驗。在實驗中，他通過寄生蠕蟲在綜合硬化症病人體內造成感染，從而觀察病人的抗病效率。在三個月裏，病人大腦神經細胞周圍活躍的病變數從原本的平均6.6個降到2個。但是，在實驗結束後，病變的數量在兩個月內反彈到了5.8個。在早期的實驗中，這些寄生蟲確實對治療潰瘍性大腸炎和克羅恩氏病發揮了積極作用。目前，寄生蟲治療還停留在試驗階段。然而，它的消極作用超過了它的積極作用。現在，在食品和藥物管理局對蠕蟲進行限定性規定，安全性得到證明以前暫時不能銷售。只許可豬鞭蟲這一個品種進入新藥的試驗階段。

therapy

7.病毒治療

One of the most exciting and promising branches of medicine in recent decades is virotherapy, a biotechnology technique to reprogram viruses to treat disease. In 2005, researchers at UCLA announced that they had turned one of humanity's deadliest enemies into a cancer-killer when they reprogrammed a modified strain of HIV to hunt down and destroy cancer cells. Around the same time, researchers at the Mayo Clinic in Rochester, Minnesota modified the measles virus to do the same.

近十年來，病毒治療可以說是最讓人驚喜和有效的醫學分科之一了。病毒治療通過生物科學技術來將病毒進行重新組合，從而達到治療疾病的目的。2005年，加利福尼亞大學洛杉磯分校的研究人員宣佈他們已經成功把人類最致命的敵人變成了癌症剋星。他們對一個轉化艾滋病菌種進行重新組合來狙擊和摧毀癌細胞。與此同時，明尼蘇達州羅切斯特市的梅奧診所的研究人員通過轉化麻疹病毒也實現了同樣的目的。

The technique is similar to the one used to breed genetically engineered plants, in that a virus is used as a gene-delivery vehicle. It has long been recognized as the most efficient means of gene transfer. This system is used for the production of useful proteins in gene therapy and has great potential for the treatment of immunological disorders such as hepatitis and ses have been known to have the potential to treat cancer since the 1950s, but the advent of chemotherapy slowed its progress. Today, virotherapy is proving to be extremely effective against tumors without harming the healthy cells around it. Clinical trials of oncolytic virotheraphy have shown low toxicity and promising signs of efficacy. In 2013, a drug called talimogene laherparepvec (TVEC) became the first drug based on a tumor-killing virus to succeed in late-stage of the biggest challenges facing researchers is how to deliver the virus where it will do the most good before the body recognizes it as an intruder and mounts a defense. Current research is looking into finding natural tumor-targeting "carriers," cells that can deliver the virus without either the cell or the virus losing its normal biological functions.

與培育基因工程植物一樣，病毒在這項技術裏同樣扮演着基因載體的角色。人們將它視爲最有效的基因載體。這個系統廣泛應用於生產某種蛋白，這種蛋白可在基因療法中使用。同時，它在治療免疫系統紊亂導致的肝炎和艾滋病時也有一定的潛力。從二十世紀五十年代起，人們就已經知道了病毒在治療癌症上的潛力。但是，化學療法的出現減緩了這一進程。現如今，研究證明，病毒療法能夠極爲有效的抗擊腫瘤而不傷害其周圍的健康細胞。在臨牀實驗中，腫瘤的病毒療法的毒性較低且效果顯著。在2013年，一種新的藥物alimogene laherparepvec (TVEC)在最後階段的試驗中獲得成功，成爲第一種以抗癌病毒爲基礎的病毒。研究人員面臨的最大的一個挑戰就是如何在人體對"入侵的病毒"進行防禦之前，將病毒放置在它可以發揮最大效用的地方。現階段的研究致力於尋找一種自然的腫瘤靶向載體細胞，從而實現在放置病毒的同時不損傷細胞或病毒的正常生物功能的目的。

g Viruses To Cure Bacterial Infections

6.利用病毒治療細菌感染

Bacteriophages are viruses that specifically attack bacteria. First recognized by Frederick Twort in 1915 and Felixd'Herelle two years later, they have been used to study many aspects of viruses since the 1930s. They are especially common in soil, where many species of bacteria make their home.

噬菌體是一類專門攻擊細菌的病毒。這種病毒是在1915年由弗雷德裏克·特沃特發現，1917費力克斯·德海萊也發現該病毒。自19世紀30年代以來，他們一直致力於對這種病毒的多方面研究。這類病毒與細菌都生長於土壤之中，土壤是許多細菌的成長大本營。

Because phages disrupt the metabolism of bacteria and destroy them, it has been long recognized that they could play a role in treating a wide range of bacterial diseases. Because of the innovation of antiobiotics, though, phage therapy was mostly shelved until the rise of antibiotic-resistant bacteria generated a renewed interest in the individual phage species is generally only effective against a small range of bacteria or even one specific species (its primary host species), which was originally seen as a disadvantage. As we have learned more about the beneficial aspects of our natural flora, though, it has come to be recognized as the advantage that it is. Unlike antibiotics, which tend to kill bacteria indiscriminately, bacteriophages can attack the disease-causing organisms without harming any other bacteria living inside e bacteria can develop resistance to both antibiotics and phages, it only takes a few weeks rather than a few years to develop new strains of phages. Phages can also have an easier time penetrating the body and locating their target, and once the target bacterium is destroyed, they stop reproducing and soon die out.

因爲噬菌體能打亂細菌的新陳代謝並破壞它們，所以科學家們意識到，噬菌體在治療細菌性疾病方面能夠發揮作用。但是因爲抗生素的革新，噬菌體的療法被擱置了。直到耐抗生素的病毒出現，科學家們才重新對這一領域產生興趣。一種噬菌體通常只對很小一部分的細菌有效，甚至只對一種細菌（主要宿主）有效。在最初，這也被看成它的一個缺點。但隨着我們對自然植物特性瞭解的增多這卻被看成了噬菌體的一個優點。與抗生素任意地攻擊細菌不同，噬菌體能在不傷害任何居住在我們體內細菌的情況下，攻擊致病微生物。雖然細菌會阻礙抗生素和噬菌體的生長，但是開發一種新的噬菌體只需花幾個星期而不是幾年時間，並且，噬菌體更容易穿透人體並且找到它們的目標，一旦它們的目標細菌被消滅了，這些噬菌體也會停止繁殖，並很快死亡。

翻譯:murphy 來源:前十網