10.The Viruses We Carried Out Of Africa Helped Us Survive
10.优胜劣汰，古老病毒们有奇功
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.
随着病毒分子遗传学的进步，我们才知道原来有那么多寄生虫在影响着人类进化。准确地说，这些把人类当顺风车的寄生虫在人类迁徙进化的历程中帮了不少忙。首先，这些外来微生物寄居在人体内，使人体产生一定排斥反应，从而形成一种迫使人类进化的推动力，正是在这种作用下，我们才有了今天这样强大的免疫系统。另外，在人体细胞表面有一些可以和细菌等微生物结合的特定受体，这些细菌和受体结合发生复杂的反应，往往会导致人体受损生病。因此这些黏附在细胞表面的受体，大大增加了人体患病的概率。不过寄生在人体内的病毒可以清理掉许多细菌的"内应"，使人体摆脱这些疾病的干扰。抵挡住其他外来者的入侵，不仅自己的生存环境更加安全，人体也是受益良多呐。

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 role.Most 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，这些病毒，寄生虫还发挥了另一项非常重要的作用。在远古猿人时期，猿人为了生存要和其他物种竞争资源。正是它们，帮助猿人进化成智人，登上食物链的最顶端。在人类发展中，疾病使得人类遗传基因多样化以便更加适应环境的改变，帮助剔除不适应大自然的弱小个体。当第一批智人离开原先居住的大陆时，这些传染性的病毒、寄生虫、细菌也跟着出发，散播到世界各地。微生物的扩散曾给人类带来灾难性的打击，其中北美洲和欧洲的天花病毒大爆发影响最大，是人类抗击病毒历史当中最为沉重的一课。尼安德特人的灭绝也和病毒、细菌传播有关，尼安德特人原本生活在欧洲，随着其他原人的进入，他们随身携带的病毒性寄生虫也传播开来。一方面穴居的尼安德特人从未接触过这些外来物种，另一方面他们已经适应北欧的寒冷气候，鼻梁宽大，因此不能充分过滤空气中的外来微生物，因而这些微生物足以使他们致命。尽管尼人的灭绝还受其他因素影响，但病毒入侵这一点不容忽视。疾病是促进人类进化的一大驱动力。随着人类离开非洲大陆，人口不断扩增，进入新石器时代，疾病与人类发展的关系更加密切。研究发现，一些人的染色体中含有博纳病毒的基因序列，而这段基因是在四千万年前和人类本身遗传物质融合的。这表明许多古老的病毒通过逆转录将自己的基因嵌入到人类的DNA序列当中，这些对人体本身运作毫无用处的基因片段被称为"垃圾DNA"，而这种病毒被称为逆转录病毒。科学家们从垃圾DNA中提取出一万对基因片段，经过加工处理使其重新具备合成蛋白质的能力，随后再植入到实验仓鼠和猫的遗传信息中。惊人的是，这些休眠数十万年的病毒活力依旧，又开始在小动物的体内肆虐了。

9.Modern-Day Medical Uses Of Leeches And Maggots
9.当代医学妙用水蛭、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.
数千年以来，欧洲水蛭一直被用作放血术的实用药材，从痔疮到中耳炎各种病症，用途广泛。欧洲水蛭的具体医疗用法可以从公元前1500年前的埃及壁画中窥见一斑。但后来随着人们对细菌的了解逐渐深入，开始应用微生物理论来解决医疗问题，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 them.Maggots, 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 things.Maggots 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，在上世纪七十年代到八十年， 这种水蛭又重新登上医学舞台。当时的外科整容行业发现用欧洲水蛭将黑眼圈、大腿、手指、肿胀的脸里的淤血吸出来效果非常明显，除此之外，水蛭还可以促进血液流动，抑制伤口愈合以及将皮瓣组织重新连接起来。蛆，这种无头幼虫专吃各种腐烂或受病毒感染的尸体。医疗中常用它们清理腐烂的伤口，驱除异物，在治疗溃疡、烧伤、皮肤癌等许多方面效果都非常显著。这种技术就叫做清创术。许多人看到这种白色不停蠕动的无头虫感到很心塞，事实上，它们可是大自然的清理工呢。尽管水蛭、蛆这些蠕动的软体动物让人觉得心塞无比，但它们的实用价值实在是高，在2010年被美国食品药品管理局选为首推活药材。可以说是它们创造了一个新兴领域——生物医学疗法。由此也应运而生许多机构和公司开始推广这种新的医疗手段，并在市场上销售欧洲水蛭和无头幼虫。

8.Parasites And Our Immune Systems May Have Co-Evolved To Protect Us From Allergies
8.为了抗过敏，我们的免疫系统和寄生虫实现了共同进化

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.
在研究了胃肠道中寄生虫对人类的影响后，研究人员提出了一个惊人的理论。他们认为，从寄生虫入侵我们的胃肠道系统至今，为了抑制我们的免疫系统，它们一直在不断地进化着。与此同时，为了抵消这样的影响，我们的身体也在不断进化着。
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 allergies.The 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 depression.Some 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 well.Parasite 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.
对人体健康来说，最让人震惊的莫过于，一旦用现代药物将水和土壤中的寄生虫和微生物从人体内他们的生存环境中移除，我们的免疫系统实际上会因填补这种缺失而导致过敏，哮喘和湿疹发作的可能性也随之增加。新技术的应用，使得我们能够辨别出那些千百年来帮助我们的微生物。尽管还停留在基础阶段，"故友假设"（也称为卫生健康假设）也于近年来受到了日益广泛的支持。目前，人们已经在临床试验中对蠕虫进行了抗综合硬化症、炎症性肠病和过敏的测试。这项"旧友假设"的主要提出者是来自伦敦大学学院的格雷厄姆A.W.路客。他在2003年第一次提出这一理论，此后，医学界认为，该理论可以解释某些紧张和抑郁症的成因。有些人在"故友理论"这个问题上走了极端，他们认为，如果把寄生虫从人体中移除会导致健康问题，那么我们就得把他们接回来。2008年，来自威斯康辛大学的神经学教授约翰·弗莱明进行了一项实验。在实验中，他通过寄生蠕虫在综合硬化症病人体内造成感染，从而观察病人的抗病效率。在三个月里，病人大脑神经细胞周围活跃的病变数从原本的平均6.6个降到2个。但是，在实验结束后，病变的数量在两个月内反弹到了5.8个。在早期的实验中，这些寄生虫确实对治疗溃疡性大肠炎和克罗恩氏病发挥了积极作用。目前，寄生虫治疗还停留在试验阶段。然而，它的消极作用超过了它的积极作用。现在，在食品和药物管理局对蠕虫进行限定性规定，安全性得到证明以前暂时不能销售。只许可猪鞭虫这一个品种进入新药的试验阶段。

7.Virotherapy
7.病毒治疗

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.
近十年来，病毒治疗可以说是最让人惊喜和有效的医学分科之一了。病毒治疗通过生物科学技术来将病毒进行重新组合，从而达到治疗疾病的目的。2005年，加利福尼亚大学洛杉矶分校的研究人员宣布他们已经成功把人类最致命的敌人变成了癌症克星。他们对一个转化艾滋病菌种进行重新组合来狙击和摧毁癌细胞。与此同时，明尼苏达州罗切斯特市的梅奥诊所的研究人员通过转化麻疹病毒也实现了同样的目的。
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 HIV.Viruses 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 testing.One 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.
与培育基因工程植物一样，病毒在这项技术里同样扮演着基因载体的角色。人们将它视为最有效的基因载体。这个系统广泛应用于生产某种蛋白，这种蛋白可在基因疗法中使用。同时，它在治疗免疫系统紊乱导致的肝炎和艾滋病时也有一定的潜力。从二十世纪五十年代起，人们就已经知道了病毒在治疗癌症上的潜力。但是，化学疗法的出现减缓了这一进程。现如今，研究证明，病毒疗法能够极为有效的抗击肿瘤而不伤害其周围的健康细胞。在临床实验中，肿瘤的病毒疗法的毒性较低且效果显著。在2013年，一种新的药物alimogene laherparepvec (TVEC)在最后阶段的试验中获得成功，成为第一种以抗癌病毒为基础的病毒。研究人员面临的最大的一个挑战就是如何在人体对"入侵的病毒"进行防御之前，将病毒放置在它可以发挥最大效用的地方。现阶段的研究致力于寻找一种自然的肿瘤靶向载体细胞，从而实现在放置病毒的同时不损伤细胞或病毒的正常生物功能的目的。

6.Using Viruses To Cure Bacterial Infections
6.利用病毒治疗细菌感染

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.
噬菌体是一类专门攻击细菌的病毒。这种病毒是在1915年由弗雷德里克·特沃特发现，1917费力克斯·德海莱也发现该病毒。自19世纪30年代以来，他们一直致力于对这种病毒的多方面研究。这类病毒与细菌都生长于土壤之中，土壤是许多细菌的成长大本营。
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 field.An 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 us.While 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.
因为噬菌体能打乱细菌的新陈代谢并破坏它们，所以科学家们意识到，噬菌体在治疗细菌性疾病方面能够发挥作用。但是因为抗生素的革新，噬菌体的疗法被搁置了。直到耐抗生素的病毒出现，科学家们才重新对这一领域产生兴趣。一种噬菌体通常只对很小一部分的细菌有效，甚至只对一种细菌（主要宿主）有效。在最初，这也被看成它的一个缺点。但随着我们对自然植物特性了解的增多这却被看成了噬菌体的一个优点。与抗生素任意地攻击细菌不同，噬菌体能在不伤害任何居住在我们体内细菌的情况下，攻击致病微生物。虽然细菌会阻碍抗生素和噬菌体的生长，但是开发一种新的噬菌体只需花几个星期而不是几年时间，并且，噬菌体更容易穿透人体并且找到它们的目标，一旦它们的目标细菌被消灭了，这些噬菌体也会停止繁殖，并很快死亡。

翻译:murphy 来源:前十网