Animals as chemical factories
动物作为化工厂

In many ways, this horse is normal: it stands roughly 14 hands high, has dark eyes hooded by thick lashes, and makes a contented neighing sound when its coat is stroked. But its blood pulses with venom.
在许多方面，这匹马是正常的：它大约有 14 手高，黑色的眼睛被浓密的睫毛遮挡，当被抚摸毛发时发出满意的嘶鸣声。但它的血液中流淌着毒液。

For weeks, this horse has been injected with the diluted venom of snakes, generating an immune response that will be exploited to produce lifesaving antivenom. A veterinarian inserts a tube into the horse’s jugular vein to extract its blood – about 1.5 percent of its body weight – every four weeks. Each bag of horse blood is worth around $500.
几周以来，这匹马一直接受稀释的蛇毒注射，产生的免疫反应将被利用来生产拯救生命的抗蛇毒血清。一名兽医将一根管子插入马的颈静脉提取其血液——约占其体重的 1.5％——每四周进行一次。每袋马血价值约 500 美元。

Horses are just one of the many animals we use as chemical factories: there is a veritable Noah’s ark of biopharming. Every year, over 700,000 horseshoe crabs are caught and bled. Their blood is used to test for contamination in the manufacture of medical equipment and drugs. The global vaccine industry uses an estimated 600 million chicken eggs a year to produce influenza vaccines. And we boil between 420 billion and 1 trillion silkworms every year to produce silk.
马只是我们用作化学工厂的众多动物之一：生物药品领域真可谓是一座诺亚方舟。每年，有超过 70 万只鲎被捕获并抽血。它们的血液用于检测医疗设备和药物制造中的污染。全球疫苗行业每年大约使用 6 亿只鸡蛋来生产流感疫苗。而我们每年煮沸的蚕在 4200 亿到 1 万亿之间，以生产丝绸。

Some of these practices go back millennia. On a small coastal spit along the Mediterranean Sea, ancient Phoenicians harvested snails from which they derived a rich-hued pigment known as Tyrian purple. In a multistep process involving sun-drying and fermenting the gland that produces the color, 12,000 of these mollusks went into every single gram of dye. The complexity of its production, and therefore rarity of the product, made the dye expensive, costing approximately three troy pounds of gold per pound of dye. Tyrian purple was reserved for highly selective items such as the toga picta worn by the Roman elite.¹
这些实践可以追溯到几千年前。在地中海沿岸的一个小海岬上，古腓尼基人收集蜗牛，从中提取出一种被称为提尔紫的丰富色调颜料。通过一个多步骤的过程，包括日晒和发酵产生颜色的腺体，每克染料需要 12,000 个这种软体动物。其生产的复杂性以及因而导致的产品稀有性，使得这种染料价格昂贵，约需每磅染料三金衡磅的黄金。提尔紫仅用于如罗马精英所穿的图画长袍等高度选择性的物品。

Synthetic dyes have long since overtaken the animal-derived production of Tyrian purple. The same goes for most medicines, including insulin, which today is manufactured biosynthetically inside E. coli bacteria. But before 1978, insulin was made by harvesting and grinding up the pancreases of dead pigs from slaughterhouses. Some 24,000 pigs were needed to make just one pound of insulin, which could treat only 750 diabetics annually.
合成染料早已超过了动物来源的提尔紫色生产。大多数药物也是如此，包括胰岛素，如今在大肠杆菌中生物合成制造。但是在 1978 年之前，胰岛素是通过收集和研磨死去的猪的胰腺来制作的。制作一磅胰岛素需要大约 24,000 只猪，而这些胰岛素每年只能治疗 750 名糖尿病患者。

Biotechnology not only reduces the inefficiencies of collecting molecules from animals but also the harms associated with working with them in the first place. Although little is known about the welfare of the horses used in antivenom production, one study found that horses used in the manufacture of brown spider antivenom suffered from blood clots and painful lumps under their skin. Diseases also affect silkworms, killing between 10 and 47 percent of larvae, depending on the country in which they are reared.
生物技术不仅减少了从动物身上收集分子的低效，还减少了与之合作所带来的危害。尽管关于用于抗毒素生产的马的福利了解甚少，但一项研究发现，用于制造棕色蜘蛛抗毒素的马经历了血栓和皮肤下的疼痛肿块。疾病也影响蚕，导致根据养殖国家的不同，10%到 47%的幼虫死亡。

Advancements in recombinant DNA, cloning, and biomanufacturing have reduced our reliance on animals to serve as chemical factories while leading to more precise and efficient antibodies and antivenoms. We have now reached the point where just about any molecule that has historically been made from animals can be made synthetically from engineered cells. However, just because it is technically feasible to move completely away from biopharming does not mean that it will be easy. And while there has been progress in eschewing animal-derived products in some areas, such as with insulin, others, like synthetic antivenom or vaccine production, have been less straightforward. Solutions to these require not only mimicking what animal biology does naturally but doing so at scale.
重组 DNA、克隆和生物制造的进步使我们减少了对动物作为化学工厂的依赖，同时也导致了更精确和高效的抗体和抗毒素的出现。我们现在已经达到了几乎任何历史上由动物制造的分子都可以通过工程细胞合成的地步。然而，尽管从生物制造中完全转移在技术上是可行的，但这并不意味着这将是容易的。尽管在一些领域，例如胰岛素方面，已经取得了减少动物来源产品的进展，但在合成抗毒素或疫苗生产等其他领域则没有那么简单。解决这些问题不仅需要模仿动物生物学的自然功能，还需要在规模上做到这一点。

Moving away from animals  远离动物

In ancient times, the Phoenicians – and the Greeks and Romans after them – made Tyrian purple dye in the world’s first chemical industry. They began by carefully extracting hypobranchial glands (which produce various compounds, including colorful pigments) from the inner roof of the snails’ shells and letting them ferment in an airtight container. From here, they would either purify the mixture and dry it for use as a pigment or employ the fermented glands directly on fabric. In this latter process, it was crucial to monitor the pH, otherwise the cloth would be at risk of felting, or clumping together, in overly alkaline solutions. Careful management of exposure to sun and air was similarly essential, so that the mixture could oxidize enough to develop the desired purple shade, but not so much that it turned blue.²
在古代，腓尼基人——以及他们之后的希腊人和罗马人——在世界上首个化学工业中生产泰尔紫色染料。他们首先小心地从蜗牛壳的内顶提取出腮腺（这些腺体产生各种化合物，包括色彩丰富的色素），并将其放在密封容器中发酵。接下来，他们要么纯化混合物并将其干燥用于作为颜料，要么直接将发酵的腺体应用于织物。在后者的过程中，监测 pH 值至关重要，否则布料在过度碱性溶液中将有毡化或聚集在一起的风险。同样，仔细管理暴露于阳光和空气也至关重要，以便混合物能够氧化到足够的程度，以形成所需的紫色色调，但又不能氧化过度而变成蓝色。

At the height of production, so many snails were killed to make dye that a heap of discarded shells in the ancient city of Sidon was said to have ‘created a mountain 40 meters high’. But when Constantinople fell to the Ottoman Empire in 1453, the knowledge required to make Tyrian purple vanished for the next 550 years.
在生产高峰期，为制造染料而杀死了大量的海螺，以至于古城锡冬有一堆废弃的贝壳据说“形成了一座 40 米高的山”。但当君士坦丁堡在 1453 年沦陷于奥斯曼帝国时，制作提尔紫色所需的知识消失了整整 550 年。

Two popular theories explain how the knowledge was lost. The first suggests that when the Byzantine Empire fell, the Catholic Church – whose cardinals wore garments dyed with Tyrian purple – lost access to its large dye factories and were forced to transition to cheaper red garments, thus diminishing demand for the dye.³
两种流行理论解释了知识是如何丧失的。第一种理论认为，当拜占庭帝国陨落时，身穿提尔紫色染料的红衣主教的天主教会失去了对大型染料工厂的控制，不得不转向更便宜的红色服装，从而降低了对染料的需求。

Another theory suggests that the Romans overharvested Tyrian snails, diminishing their populations to the point of collapse shortly before the Ottomans arrived.⁴ Regardless of which explanation is true, the result was the same: knowledge surrounding the production of Tryrian purple lapsed and the method fell out of fashion.
另一个理论认为，罗马人过度捕捞了提尔海螺，导致其种群在奥斯曼人到来之前不久就崩溃了。 ⁴ 无论哪种解释是真实的，结果都是相同的：有关提尔紫色生产的知识逐渐消失，这种方法也因此失去了时尚。

More often, it is not lost knowledge that precipitates a move away from biopharming, but instead the discovery of a more efficient alternative.
更常见的是，推动人们远离生物制药的不是失去的知识，而是发现了更高效的替代方案。

In the 1830s, the United States was home to the world’s largest whaling industry, centered around Cape Cod in Massachusetts. More than 10,000 sailors took to the Atlantic each season, predominantly hunting right whales and humpbacks that stayed closer to shore.
在 1830 年代， 미국是世界上最大的捕鲸业的发源地，中心位于马萨诸塞州的科德角。每个季节，有超过 10,000 名水手出海进入大西洋，主要捕猎停留在离岸较近的南右鲸和座头鲸。

After the humpbacks and right whales died off, many sailors went on yearslong voyages to hunt down the more elusive sperm whale. A 15-meter-long sperm whale contains about three metric tons of oil in its spermaceti organs, an open cavity above the jaws.⁵ Whale oil was highly prized because it could be used to make candles that burned brightly and without the odor emitted by burning lard.
在座头鲸和弓头鲸灭绝后，许多水手进行了长达数年的航行，猎捕更难捕捉的抹香鲸。一头长达 15 米的抹香鲸在其鲸蜡腺中含有约三公吨的油，这是位于下颌上方的一个开放腔体。鲸油非常珍贵，因为它可以用来制造燃烧明亮且没有猪油燃烧时散发气味的蜡烛。

In the 1850s, Scottish chemist James Young figured out how to make paraffin wax from coal and oil shales at commercial scales, reducing the market for spermaceti. Just as well, because at its peak in the mid-nineteenth century, whalers killed over 5,000 sperm whales a year. There were an estimated two millions sperm whales in 1712, before the start of commercial whaling. Today, there are about 850,000 sperm whales; a decline of approximately 57% in 310 years. It’s estimated that, by 2001, 12 years after whaling had ended in nearly every country, there were around 99 percent fewer blue whales, as well as 89 percent fewer right whales and bowhead whales, than in 1890. Populations have barely recovered today.
在 1850 年代，苏格兰化学家詹姆斯·杨发现如何从煤和油页岩中以商业规模生产石蜡，这减少了对捕鲸脂的市场。值得庆幸的是，因为在 19 世纪中叶，高峰时期捕鲸者每年杀死超过 5000 头抹香鯨。据估计，1712 年在商业捕鲸开始之前，抹香鯨的数量有约 200 万头。如今，抹香鯨大约有 85 万头；在 310 年间下降了约 57%。据估计，到 2001 年，在几乎所有国家的捕鲸结束 12 年后，蓝鲸的数量比 1890 年减少了约 99%，而右鲸和弓头鲸的数量也减少了 89%。如今，种群几乎没有恢复。

This same trend, wherein animal-based manufacturing gives way to more humane and efficient alternatives, has also played out in circumstances where we could still readily use animals, but choose not to.
这种趋势，即以动物为基础的制造业让位于更人道和更高效的替代品，也在某些情况下得以体现，尽管我们仍然可以轻松使用动物，但选择不这样做。

Consider the steep rise and precipitous fall of pigs used for insulin production.
考虑用于胰岛素生产的猪的急剧上升和迅速下降。

Insulin is a small protein (actually two small, interlocking proteins called A and B), produced by the pancreas that signals cells to take in sugar from surrounding blood. People with diabetes either don’t produce enough insulin (type one), or their cells don’t respond to insulin appropriately (type two). This causes sugar to build up in the bloodstream, slowly damaging the eyes, kidneys, and nervous system.
胰岛素是一种小蛋白质（实际上是两种相互连接的小蛋白质，称为 A 和 B），由胰腺产生，提示细胞从周围的血液中吸收糖分。糖尿病患者要么无法产生足够的胰岛素（1 型糖尿病），要么其细胞对胰岛素的反应不当（2 型糖尿病）。这会导致血液中的糖分积累，逐渐损害眼睛、肾脏和神经系统。

In 1922, Dr. Frederick Banting and his student, Charles Best, discovered that the pancreas contains a compound, later identified as insulin, that could reduce blood sugar levels in humans. In their original paper, the men describe how they gave dogs a lethal dose of chloroform before swiftly excising and macerating the ‘degenerated pancreas’, only to then filter the substance through paper and inject it into the veins of a 14-year-old boy. Crude as it was, they wrote that ‘Fortune favored us in the first experiment’. The extract successfully reduced the amount of sugar excreted in the boy’s urine.
在 1922 年，弗雷德里克·班廷博士和他的学生查尔斯·贝斯特发现，胰腺中含有一种化合物，后来被确定为胰岛素，能够降低人类的血糖水平。在他们的原始论文中，这两位男士描述了他们是如何给狗注射致死剂量的氯仿，然后迅速切除并捣碎“退化的胰腺”，接着将提取物过滤后注射到一名 14 岁男孩的静脉中。他们写道，尽管过程粗糙，“但好运为我们在第一次实验中所助”。这种提取物成功减少了男孩尿液中的糖分排泄量。

That same year, the Eli Lilly company in Indianapolis struck an agreement with Banting and Best to mass-produce insulin by harvesting animal pancreases. By 1923, the company was selling Iletin, the first American insulin product to treat diabetes. Eli Lilly quickly came to dominate the US market, with $160 million in annual revenue by 1976.
同年，位于印第安纳波利斯的伊利莉公司与班廷和贝斯特达成协议，通过收集动物胰腺大规模生产胰岛素。到 1923 年，该公司推出了 Iletin，这是第一款用于治疗糖尿病的美国胰岛素产品。到 1976 年，伊利莉迅速主导了美国市场，年收入达 1.6 亿美元。

Around the same time, Eli Lilly executives became concerned when a graph began to circulate around the company. It showed two lines: one tracing the available supply of pig and cow pancreases, and another tracking the rate of diabetes prevalence in the USA, which was then rising by about five percent each year as more people were being diagnosed and surviving for longer. Its implications for the insulin market were alarming: Eli Lilly would soon fall short of demand.
与此同时，礼来公司高层开始担忧一张图表在公司内部流传。图表上有两条曲线：一条显示猪和牛胰腺的可用供应量，另一条追踪美国糖尿病患病率的变化，后者当时每年约上升五个百分点，因为越来越多的人被诊断出来并且存活时间更长。这对于胰岛素市场的影响令人震惊：礼来公司很快将无法满足需求。

To circumvent this shortfall, the company organized an insulin symposium, inviting the brightest minds from the pharmaceutical and molecular biology fields to come together to discuss whether genetic engineering could be used to make insulin. What if it were possible to isolate the gene encoding insulin in human cells, say, and insert it into living bacteria? Could the microbes be induced to manufacture the molecule? And would such a molecule be chemically and functionally equivalent to the human version? By 1978, a scientist named David Goeddel, along with his colleagues at Genentech, a biotech startup in San Francisco, had provided an answer to all three questions. They used chemistry to build human insulin genes (chain A and B), one nucleotide at a time, and inserted them into Escherichia coli cells. The engineered microbes began making human insulin proteins.
为了应对这一短缺，公司组织了一场胰岛素研讨会，邀请制药和分子生物学领域的顶尖学者共同探讨是否可以利用基因工程来制造胰岛素。假如能够从人类细胞中分离出编码胰岛素的基因，并将其插入活细菌中，那会怎样呢？这些微生物能否被诱导制造这种分子？这样的分子在化学和功能上是否与人类版本相同？到 1978 年，一位名叫大卫·戈德尔的科学家和他在旧金山生物技术初创公司基因科技的同事们已经对这三个问题提供了答案。他们使用化学方法逐个核苷酸地构建人类胰岛素基因（A 链和 B 链），并将其插入大肠杆菌细胞中。这些工程微生物开始制造人类胰岛素蛋白。

Not only had the Genentech scientists created human insulin in microbes, but they had managed to create a product that was even more reliable than the extracts derived from animals, whose potency varied up to 25 percent per lot. And whereas some diabetics responded to animal insulin with allergic skin reactions, reactions to synthetic forms of insulin were rare.
不仅基因科技的科学家们在微生物中制造了人类胰岛素，他们还成功创造了一种比从动物提取物中得到的产品更可靠的胰岛素，而动物提取物的效力每批次可能变化高达 25%。而且，虽然一些糖尿病患者对动物胰岛素会产生过敏皮肤反应，但对合成胰岛素的反应则很少见。

The understanding of biology that crystallized in this period was this: all animals are made of cells that encode their genetic material in the form of DNA. If scientists can identify the genetic sequences responsible for a particular molecule, be it an antivenom, an antibody, or a purple dye, then those sequences can be spliced into cells to produce molecules in the laboratory.
在这个时期形成的生物学理解是：所有动物都是由细胞构成的，这些细胞以 DNA 的形式编码其遗传物质。如果科学家能够识别出负责特定分子的基因序列，无论是抗毒素、抗体还是紫色染料，那么这些序列可以被拼接到细胞中，以在实验室中生产分子。

Making molecules  制造分子

As improbable as it may seem, all life on Earth stems from the same organic molecules. Some of these molecules, known as nucleotides or bases, but perhaps more familiar as A, T, C, and G, act as the building blocks of genetic information. The DNA belonging to a puffer fish is chemically identical to the DNA of a tree. The order of their bases differ, of course, but the DNA molecules found in one organism are often interpretable by other life-forms.⁶ A gene encoding insulin in a person can be cloned, inserted into microbes, and quickly propagated in the laboratory. Microbes reproduce quickly – E. coli cells split in two every 20 minutes – and so can make vast quantities of biological products on short timescales.
尽管看起来不太可能，但地球上的所有生命都源于相同的有机分子。这些分子被称为核苷酸或碱基，或许更为人所熟知的是 A、T、C 和 G，它们作为遗传信息的构建块。河豚的 DNA 在化学上与一棵树的 DNA 相同。当然，它们的碱基顺序不同，但在一个生物体中发现的 DNA 分子往往可以被其他生命形式解读。 ⁶ 一个编码胰岛素的基因可以在实验室中克隆，插入到微生物中，并迅速繁殖。微生物繁殖很快——大肠杆菌细胞每 20 分钟分裂一次——因此可以在短时间内制造大量生物产品。

The first step in making an animal product in the laboratory is to identify the genes responsible. But this is easier said than done. Genes are not merely strings of DNA that encode proteins, as students are taught in school. Some genes make RNA, for example, that are never converted into proteins at all; instead, they control the expression of other genes in the genome.
在实验室制造动物产品的第一步是识别负责的基因。但这说起来容易，做起来难。基因不仅仅是编码蛋白质的 DNA 串，如学生在学校所学的那样。举例来说，有些基因会制造 RNA，而这些 RNA 根本不会转化为蛋白质；相反，它们控制着基因组中其他基因的表达。

It used to take months or years for scientists to figure out which particular strings of DNA were responsible for making a particular protein in cells. Although DNA’s atomic structure was resolved in 1953, the first gene, encoding a coat protein, or outer shell of a bacteriophage, was not fully sequenced until 1972.
科学家们过去需要几个月甚至几年的时间才能搞清楚哪些特定的 DNA 序列负责在细胞中制造特定的蛋白质。尽管 DNA 的原子结构在 1953 年得以解析，但编码噬菌体外壳蛋白的第一个基因直到 1972 年才完全测序。

Techniques to sequence DNA slowly percolated through academic circles in the late 1970s. The first commercial, automated DNA sequencer was released in 1987. In 2001, it cost about $100 million to sequence three billion bases of DNA in the human genome. Twenty years later, the same feat cost about $700.
DNA 测序技术在 20 世纪 70 年代末逐渐渗透到学术界。第一台商业化的自动 DNA 测序仪于 1987 年发布。2001 年，测序人类基因组中的三十亿个碱基的费用约为 1 亿美元。二十年后，同样的成就费用约为 700 美元。

A gene, however, is little more than a string of bases: As, Ts, Cs, and Gs. And a DNA sequence alone is not always sufficient to infer the function of the protein it encodes. Just by looking at the insulin gene’s sequence, for example, one would not necessarily know that it encodes a protein that lowers blood sugar levels. That observation must be deduced experimentally.
一个基因，不过就是一串碱基：A、T、C 和 G。单独的 DNA 序列并不总是足以推断出它所编码的蛋白质的功能。例如，仅仅通过观察胰岛素基因的序列，无法确定它编码的是一种降低血糖水平的蛋白质。这个观察必须通过实验推导出来。

Emerging AI tools, such as AlphaFold 3, can predict the structure of a protein from a DNA sequence, but a protein’s structure doesn’t always indicate its function. The tried-and-true way to figure out a gene’s function is to delete it from the genome and then watch what happens to the organism. If you delete the insulin-coding gene, blood sugar levels spike.
新兴的人工智能工具，如 AlphaFold 3，可以根据 DNA 序列预测蛋白质的结构，但蛋白质的结构并不总能指示其功能。确定基因功能的可靠方法是将其从基因组中删除，然后观察生物体会发生什么。如果删除编码胰岛素的基因，血糖水平会飙升。

Once scientists determine the gene responsible for a particular protein, such as an antibody or insulin, that gene can be cloned and inserted into quickly dividing cells in the laboratory. The basic technology to do this has existed for more than 50 years, and there are three overarching steps: first, scientists make DNA that encodes a protein of interest, such as insulin or antibodies or antivenom. Then, they insert that DNA into living cells. Molecular machines inside of the cells will ‘read’ the DNA and transcribe it into messenger RNA, which ribosomes – large enzymes made from proteins and RNA – then use to assemble proteins. And third, scientists kill the cells and isolate the proteins.
一旦科学家确定了负责特定蛋白质的基因，例如抗体或胰岛素，这个基因就可以在实验室中克隆并插入快速分裂的细胞中。这项基本技术已经存在超过 50 年，主要包括三个步骤：首先，科学家制造编码感兴趣的蛋白质的 DNA，例如胰岛素、抗体或抗蛇毒血清。然后，他们将这些 DNA 插入活细胞中。细胞内的分子机器将“读取”DNA，并将其转录为信使 RNA，然后由大分子酶——由蛋白质和 RNA 组成的核糖体——利用这些 RNA 来组装蛋白质。最后，科学家杀死细胞并提取蛋白质。

The first step in this process was cracked in 1972, when a graduate student at Stanford University named Janet Mertz isolated DNA strands from two distinct organisms and then cut them with a restriction enzyme, a type of protein that slices DNA molecules in precise locations. Restriction enzymes leave behind sticky ends, or short overhanging sequences, that can be joined together to create a chimeric strand of genetic material. Mertz’s experiment suggested, for the first time, that DNA from a horse, penguin, or jellyfish could be cut and pasted into a bacterial genome, for example.
这一过程的第一步在 1972 年取得突破，当时斯坦福大学的研究生珍妮特·梅茨（Janet Mertz）从两种不同的生物中分离出 DNA 链，然后用限制性酶切割它们。限制性酶是一种在精确位置切割 DNA 分子的蛋白质。限制性酶留下粘性末端或者短的悬挂序列，可以结合在一起形成嵌合的遗传物质链。梅茨的实验首次表明，例如，一匹马、一个企鹅或一只水母的 DNA 可以被切割和粘贴到细菌基因组中。

The following year, two groups at Stanford and the University of California, San Francisco, repeated Mertz’s experiment, but took things a step further by inserting the chimeric DNA into E. coli cells. The engineered microbes successfully copied and propagated the chimeric DNA.
次年，斯坦福大学和加利福尼亚大学旧金山分校的两个团队重复了梅尔茨的实验，但将实验更进一步，将嵌合 DNA 插入了大肠杆菌细胞中。这些工程微生物成功复制并传播了嵌合 DNA。

At the time of Mertz’s experiments, the only way to obtain a particular DNA sequence was to obtain physical access to the relevant organism, be it a horse, whale, or something else entirely, and then use molecular scissors (enzymes that precisely cut DNA at specific locations) to cut out the desired gene from frozen tissue.
在梅茨实验时，获得特定 DNA 序列的唯一方法是获得相关生物的实物接触，不论是马、鲸鱼还是完全不同的生物，然后使用分子剪刀（在特定位置精确切割 DNA 的酶）从冷冻组织中切出所需的基因。

Today, companies such as Twist Bioscience can synthesize DNA for about $0.07 per base. The average human gene has a protein-coding sequence stretching a bit more than 1,000 bases in length, so it costs a bit less than $100 to chemically synthesize an average-sized human gene. It is no longer necessary to obtain physical samples of genetic information. One can simply search for a gene in a public database, download the sequence, and then order it from a DNA synthesis company.
今天，像 Twist Bioscience 这样的公司可以以每个碱基约 0.07 美元的价格合成 DNA。平均人类基因的蛋白质编码序列长度稍超过 1,000 个碱基，因此化学合成一个平均大小的人类基因的成本略低于 100 美元。现在不再需要获取遗传信息的实物样本。人们只需在公共数据库中搜索基因，下载序列，然后向 DNA 合成公司下订单。

Once scientists obtain a DNA sequence, either the old way, by cutting it from animals, or the newer way, by synthesizing it chemically, they splice that into a loop of DNA, called a plasmid, which they then insert into living cells. Scientists commonly make this insertion through the use of either chemicals or electricity.
一旦科学家获得 DNA 序列，无论是通过传统的方式从动物中切割，还是通过新的化学合成方式，他们将其拼接到一个称为质粒的 DNA 环中，然后将其插入活细胞。科学家通常通过化学物质或电力来实现这一插入。

The chemical approach, invented in 1970, uses calcium ions to coat negatively charged DNA strands and push those strands past a microbial cell’s membrane. The electrical approach, called electroporation, was first described in 1982 and works by zapping cells with electrical pulses. Each zap punches little holes in the membrane, which DNA can pass through.
化学方法于 1970 年发明，利用钙离子涂覆带负电的 DNA 链，并将这些链推过微生物细胞膜。电气方法称为电穿孔，首次描述于 1982 年，通过用电脉冲刺激细胞来实现。每一次刺激都会在膜上打出小孔，DNA 可以穿过这些孔。

Once you have got DNA encoding, say, a human insulin gene into a cell, the cell will begin to read the genetic information and churn out human insulin. The cells also divide, copy the loops of DNA, and pass the insulin genes onto their progeny. After a few hours, one transformed cell becomes billions of clones, each carrying the engineered DNA and making lots of human insulin. The same basic technology can be used to make antibodies and other proteins, too.
一旦将编码人类胰岛素基因的 DNA 导入细胞，细胞将开始读取遗传信息并产生人类胰岛素。这些细胞也会分裂，复制 DNA 环，并将胰岛素基因传给它们的后代。经过几小时的时间，一个转化的细胞会变成数十亿个克隆，每个克隆都携带着工程化的 DNA 并制造大量的人类胰岛素。相同的基本技术也可以用来制造抗体和其他蛋白质。

Not all cells are well-suited to making all molecules, though. When Genentech made human insulin, they used E. coli bacteria. But today, many drugs are made using mammalian cells instead.
并非所有细胞都适合制造所有分子。当基因泰克公司生产人类胰岛素时，他们使用了大肠杆菌。但是如今，许多药物是使用哺乳动物细胞生产的。

Monoclonal antibodies, for example, are Y-shaped proteins that tightly bind to specific molecules. Each of these antibodies is made from two proteins, called the light chain and heavy chain, which interlock to form the complete antibody.
单克隆抗体，例如，是一种 Y 形蛋白，紧密结合特定分子。这些抗体由两种蛋白质构成，称为轻链和重链，它们交错在一起形成完整的抗体。

Many of the most widely prescribed pharmaceutical drugs, including the immunosuppressant adalimumab (sold as Humira, and generating over $21 billion in sales in 2021) and cancer therapy pembrolizumab (sold as Keytruda, generating over $17 billion in the same year) are monoclonal antibodies. But only a few different organisms, mainly mammalian cells and yeasts, can make them because antibodies are glycosylated, or tagged with sugar molecules, and bacteria cannot naturally perform this reaction.⁷
许多最广泛处方的药物，包括免疫抑制剂阿达木单抗（以 Humira 销售，2021 年销售额超过 210 亿美元）和癌症治疗药物帕博利珠单抗（以 Keytruda 销售，同年销售额超过 170 亿美元），都是单克隆抗体。但只有少数不同的生物体，主要是哺乳动物细胞和酵母，能制造它们，因为抗体是糖基化的，或与糖分子标记的，而细菌无法自然执行这种反应。

Most monoclonal antibodies are generated using Chinese hamster ovary, or CHO, cells, which initially descended from cells taken from a hamster’s ovary and were later immortalized.⁸ Robert Briggs Watson, a Rockefeller Foundation field staff member based in China, smuggled these hamsters out of the country on one of the last Pan Am flights from Shanghai, just before Mao Zedong and the Communists took over. Today, CHO cells make about 70 percent of all therapeutic proteins sold on the market.
大多数单克隆抗体是使用中国仓鼠卵巢细胞（CHO 细胞）生成的，这些细胞最初来源于从仓鼠卵巢获取的细胞，并随后被永生化。 ⁸ 罗伯特·布里格斯·沃特森（Robert Briggs Watson）是驻中国的洛克菲勒基金会外勤人员，他在毛泽东和共产党接管之前，通过最后一班从上海出发的泛美航班走私出了这些仓鼠。如今，CHO 细胞生产的治疗性蛋白质占市场上销售的所有治疗性蛋白质的约 70%。

Once CHO cells are transformed with genes encoding the heavy and light chains for a particular antibody, they begin to express the genes and make the proteins. One liter of CHO cells can generally produce about four grams of antibodies, but this number varies widely, from mere milligrams to more than ten grams per liter, based on the specific antibody and culture conditions.
一旦 CHO 细胞通过编码特定抗体的重链和轻链基因发生转化，它们就开始表达这些基因并合成蛋白质。一升 CHO 细胞通常可以生产约四克抗体，但这个数字差异很大，从仅几毫克到每升超过十克，这取决于特定抗体和培养条件。

The final step in biomanufacturing is scale. Cells that generate the most antibodies in small volumes are transferred into large, steel bioreactors, generally up to 10,000 liters in volume. Each bioreactor has spinning blades inside that agitate the cells to ensure they are well-mixed and oxygenated. After waiting several days for the cells to secrete antibodies to a high concentration, scientists remove the cells and purify the antibodies.
生物制造的最后一步是规模。产生最多抗体的小体积细胞被转移到大型钢制生物反应器中，通常容量可达到 10,000 升。每个生物反应器内部都有旋转的叶片，用于搅拌细胞，确保它们充分混合并获得氧气。在等待几天让细胞分泌高浓度抗体后，科学家们去除细胞并纯化抗体。

Reasons for animals  动物的原因

If most animal products today can be made by means of biotechnology, then why do we still use animal products to make flu vaccines, tests for microbial contamination in drugs, and many antibodies? Three prevailing reasons come to mind, which we’ll call regulatory lock-in, molecular complexity, and ease of scaling.
如果今天大多数动物产品可以通过生物技术制造，那么我们为什么仍然使用动物产品来制造流感疫苗、药物中的微生物污染测试以及许多抗体呢？我们想到三个主要原因，可以称之为监管锁定、分子复杂性和规模化的便利性。

Horseshoe crab blood is an example of regulatory lock-in: though we have known how to make synthetic alternatives for decades, regulators have only recently approved them. Every year, biomedical companies along the eastern coast of the United States continue to collect and drain blood from hundreds of thousands of horseshoe crabs for use in endotoxin tests.⁹
马蹄蟹的血液是监管锁定的一个例子：尽管我们已经知道如何制作合成替代品数十年，但监管机构直到最近才批准它们。每年，美国东海岸的生物医学公司仍继续从数十万只马蹄蟹身上收集和抽取血液，以用于内毒素测试。 ⁹

Horseshoe crabs’ characteristic blue-colored blood contains a molecule called LAL, or limulus amebocyte lysate, which forms a gel-like clump when exposed to bacterial molecules called endotoxins. Endotoxins are long molecules made of sugars and fat that stick on the outer walls of some bacteria and, if introduced into a patient, can cause septic shock. The LAL in horseshoe crabs’ blood allows scientists to detect the presence of these endotoxins in medicines and vaccines, and filter them out.
马蹄蟹特有的蓝色血液中含有一种叫 LAL（或称为林氏单核细胞裂解液）的分子，当暴露于一种称为内毒素的细菌分子时，会形成类似凝胶的团块。内毒素是由糖和脂肪组成的长链分子，附着在某些细菌的外壁上，如果进入患者体内，可能导致脓毒性休克。马蹄蟹血液中的 LAL 使科学家能够检测药物和疫苗中这些内毒素的存在，并将其过滤掉。

Synthetic versions of LAL have been made using recombinant DNA technology since the 1990s. And in 2020, two important shifts happened: Eli Lilly tested all of their Covid-19 antibody medicines using synthetic horseshoe crab blood, and the European Pharmacopoeia, a nonprofit organization that evaluates medical products for safety, approved the use of synthetic alternatives. Academic reviews comparing synthetic versions to naturally derived horseshoe crab blood confirm that ‘the recombinant technologies are comparable in protecting patient safety’.
自 1990 年代以来，合成版本的 LAL 已经通过重组 DNA 技术制造。2020 年发生了两个重要变化：礼来公司测试了所有的 Covid-19 抗体药物，使用合成的 horseshoe crab 血液，同时欧洲药典（European Pharmacopoeia）——一个评估医疗产品安全性非营利组织——批准了使用合成替代品的申请。学术评审比较合成版本与自然派生的 horseshoe crab 血液，确认“重组技术在保护患者安全方面是可比的”。

Despite this, the US has been slow to adopt synthetic alternatives. It was only in late July of this year that the US Pharmacopeia finally approved language to permit ‘the use of non-animal-derived reagents for endotoxin testing’. How quickly this shift will take place is anyone’s guess, but considering how dependent we have become on animal-derived LAL, it is naive to assume that the switch will be rapid.
尽管如此，美国在采用合成替代品方面进展缓慢。直到今年 7 月底，美国药典才最终批准了允许“使用非动物来源的试剂进行内毒素检测”的措辞。这个转变将多快发生无人可知，但考虑到我们在多大程度上依赖于动物来源的 LAL，认为转换会迅速发生是天真的。

In the case of molecular complexity, consider antivenoms. The method to make antivenom has not changed much over the last 100 years. Venom is first milked from snakes and then injected into horses or sheep, which then produce multiple different antibodies and antibody fragments that bind to the venom. These are known as polyclonal antibodies. Blood is collected from these animals, the antibodies are purified from the plasma, and they are then given to people bitten by venomous snakes.
在分子复杂性的情况下，考虑抗毒素。制造抗毒素的方法在过去 100 年中变化不大。首先从蛇身上提取毒液，然后注射到马或羊体内，这些动物会产生多种不同的抗体和与毒液结合的抗体片段。这些被称为多克隆抗体。从这些动物身上采集血液，抗体从血浆中纯化出来，然后给被毒蛇咬伤的人使用。

There are a few problems with this approach. In particular, polyclonal antibodies are difficult to make synthetically because they are concoctions of molecules, and finding the correct antivenom often requires identifying the precise snake species responsible for the bite. It’d be far better to create synthetic antivenoms that could neutralize many different types of venoms, which we call multiplex antivenoms.
这种方法存在几个问题。特别是，多克隆抗体难以通过合成制备，因为它们是分子的混合物，找到正确的解毒药通常需要识别出导致咬伤的确切蛇种。创造能够中和多种不同类型毒素的合成解毒药，也就是我们所称的多重解毒药，将是更好的选择。

We have made some progress toward these multiplex antivenoms, but commercially available versions are likely many years away. A recent study, published in Science Translational Medicine in February, reported the discovery of a human monoclonal antibody that could neutralize long-chain three-finger-neurotoxins, basically molecular tags found in many different antivenoms, in cells. This antibody, injected into mice, protected the animals against otherwise lethal doses of venom. And because it is a monoclonal antibody, rather than a mixture of antibodies, it can be readily manufactured using recombinant DNA technology and the Chinese hamster ovary cells we rely on in so many other circumstances. The monoclonal antibody must be tested in human trials, but it’s an important step toward building broadly neutralizing antivenoms at scale.¹⁰
我们在这类多重抗毒素方面取得了一些进展，但商业上可获得的版本可能还需要许多年。最近一项发表于《科学转化医学》杂志的研究报告发现了一种人类单克隆抗体，它能够中和长链三指神经毒素，这基本上是多种不同抗毒素中发现的分子标签。在小鼠体内注射这种抗体可以保护这些动物免受致命剂量毒液的影响。由于它是一种单克隆抗体，而不是抗体的混合物，因此可以使用重组 DNA 技术和我们在许多其他情况下依赖的中国仓鼠卵巢细胞轻松制造。该单克隆抗体必须在人体试验中进行测试，但这向大规模生产广谱中和抗毒素迈出了重要一步。

This brings us to the issue of scale. Animals are still used to make medicines and vaccines because that is sometimes still the simplest and cheapest approach. This is evident in how we produce seasonal flu vaccines.
这使我们面临规模的问题。动物仍然被用来制造药物和疫苗，因为有时这仍然是最简单和最便宜的方法。这在我们生产季节性流感疫苗的方式中显而易见。

Since at least 1931, vaccinologists have used fertilized chicken eggs to make influenza vaccines. Two scientists at Vanderbilt University, named Ernest Goodpasture and Alice Woodruff, discovered that eggs injected with a small amount of virus were ideal vessels for enabling those viruses to multiply and propagate. After a few days of incubation, during which viruses build up in the egg, a small hole is punched through its shell, and the fluid within is removed. From here, viral particles are carefully purified and inactivated, after which they can be mixed in cocktails and injected into humans.
自 1931 年以来，疫苗学家一直使用受精鸡蛋来制作流感疫苗。范德比尔特大学的两位科学家，恩斯特·古德帕斯特和爱丽丝·伍德拉夫发现，注射少量病毒的鸡蛋是使这些病毒繁殖和传播的理想载体。经过几天的孵化，在此期间病毒在鸡蛋中积累后，蛋壳上打一个小孔，取出内部的液体。从这里，病毒颗粒被小心地净化和灭活，然后可以与其他成分混合并注射到人类体内。

A single egg can produce several milligrams of vaccine, and while it might seem like a large bioreactor could make more, there are only about 61 million liters of global biomanufacturing capacity, of which only 10 million liters are unreserved. And not only that, but the reactors themselves can only be so large before the cells inside die from lack of proper oxygenation. In light of this, eggs are comparably cheap and easy to come by: in 2023, the US vaccine industry used less than one percent of the 110 billion eggs produced that year.
一个鸡蛋可以生产几毫克疫苗，虽然看起来大型生物反应器可以生产更多，但全球的生物制造能力仅约为 6100 万升，其中只有 1000 万升是未被预留的。而且，反应器本身也有大小限制，超出后内部细胞会因缺乏适当的氧气而死亡。考虑到这一点，鸡蛋相对便宜且容易获得：在 2023 年，美国疫苗行业使用的鸡蛋不到当年生产的 1100 亿个鸡蛋的百分之一。

Of the roughly 175 million flu vaccines administered in the US in 2020, about 82 percent were manufactured using eggs, according to the CDC. Still, this approach has several drawbacks. First, the viruses can mutate during their propagation, leading to vaccines with low efficacy. A 2017 paper, for example, found that the H3N2 virus strain used for the 2016–2017 flu vaccine carried a mutation that meant that the antibodies it elicited had poor binding abilities against flu strains circulating through the human population.
根据 CDC 的数据，2020 年在美国接种的约 1.75 亿剂流感疫苗中，约 82%是使用鸡蛋制造的。然而，该方法也存在若干缺陷。首先，病毒在繁殖过程中可能发生突变，导致疫苗的有效性较低。例如，一篇 2017 年的论文发现，2016-2017 年流感疫苗使用的 H3N2 病毒株携带一种突变，这意味着其产生的抗体对在人体群体中传播的流感株的结合能力较差。

In 2021, researchers also found that people injected with influenza vaccines were developing antibodies against part of the egg, rather than to the virus infecting the egg, which could make it more difficult for a person’s antibodies to recognize and respond to actual flu viruses.
2021 年，研究人员还发现，接种流感疫苗的人体内产生的抗体是针对蛋的一部分，而不是针对感染蛋的病毒，这可能使得一个人的抗体更难以识别和应对真实的流感病毒。

For these reasons, influenza vaccines made in eggs are significantly less effective than vaccines made from engineered cells. However, until we can find a way to produce 175 million doses per year in bioreactor tanks, moving away from eggs will remain challenging.
基于这些原因，使用鸡蛋制造的流感疫苗效果明显低于采用工程细胞生产的疫苗。然而，直到我们找到一种每年在生物反应器中生产 1.75 亿剂疫苗的方法，摆脱对鸡蛋的依赖仍然是一个挑战。

Were we to circumvent the difficulties of regulatory lock-in, molecular complexity, and scale, biopharming could readily give way to synthetic alternatives. This would be a welcome shift not only from the lens of animal welfare but also efficacy: synthetic versions are chemically identical, or even superior to, their natural analogs.
如果我们能够绕过监管锁定、分子复杂性和规模等困难，生物制药很可能会让位于合成替代品。这不仅从动物福利的角度看是一个受欢迎的转变，此外，合成版本在化学上与其自然类似物相同，甚至更优。

Animal-derived insulin was never particularly pure. Even after Eli Lilly chemists invented a method, called isoelectric precipitation, that increased the purity of insulin extracted from cows and pigs by between 10- and 100-fold, analyses showed that the purified samples still contained various unwanted peptides and contaminants. Synthetic insulin is much less likely than animal insulin to trigger serious immune responses and reactions at the injection site.
动物来源的胰岛素从来都不是特别纯净。即使在艾利·利利的化学家发明了一种名为等电沉淀的方法后，该方法将从牛和猪提取的胰岛素纯度提高了 10 到 100 倍，分析显示这些纯化样本仍然含有各种不必要的肽和污染物。合成胰岛素比动物胰岛素更不容易引发严重的免疫反应和注射部位反应。

A similar story has played out for seasonal flu vaccines. Research comparing the efficacy of egg-versus cell-based vaccines, as administered to more than 100,000 people over the period of three flu seasons, found that cell-made vaccines were consistently superior.
针对季节性流感疫苗也出现了类似的情况。研究比较了鸡蛋疫苗与细胞基础疫苗的效果，涉及超过 100,000 人在三个流感季节期间的接种情况，结果发现细胞制成的疫苗始终表现更佳。

The shift to synthetic alternatives, then, will be a move toward molecules with the potential to be both more potent and reliable than their ‘natural’ counterparts.
因此，转向合成替代品将是朝着分子转变的一个步骤，这些分子有可能比其“天然”对应物更有效且更可靠。

Even as biotechnology transforms how we derive molecules, however, we’d do well to acknowledge that the field was formed by, and continues to be built on the back of, the exploitation of biological diversity.
即使生物技术正在改变我们获取分子的方式，我们也应该承认这个领域是在对生物多样性的开发基础上形成的，并且仍然在其基础上不断发展。

CHO cells, used to make antibodies, were isolated from Chinese hamsters smuggled out of that nation in the 1940s. Modern polymerase chain reaction, a linchpin technology used in Covid-19 diagnostics, was only possible because of enzymes discovered in heat-tolerant microbes living in Yellowstone National Park. And the first protein structure was solved by purifying myoglobin from sperm whale blood samples stored in a freezer at Cambridge University.
CHO 细胞，用于制造抗体，是在 20 世纪 40 年代从被走私出中国的仓鼠中分离出来的。现代聚合酶链反应，这一在新冠病毒检测中至关重要的技术，之所以能够实现，是因为发现了生活在黄石国家公园的耐热微生物中的酶。而第一种蛋白质结构的解析则是通过从存放在剑桥大学冷冻室中的抹香鲸血样中提纯肌红蛋白实现的。

In recent decades, sequencing technologies have made it easier and cheaper than ever to decode genomes and upload the sequences to databases. It is no longer necessary for scientists to collect DNA from animal tissues directly since they can now download the sequences online and order them from DNA synthesis companies.
在最近几十年中，测序技术使解码基因组变得比以往更容易且更便宜，并将这些序列上传到数据库。科学家们不再需要直接从动物组织中采集 DNA，因为他们现在可以在线下载这些序列并从 DNA 合成公司订购它们。

There is one interpretation of this that might lead us to become less concerned about the future and plentitude of the animals we exploit for biomanufacturing. Our ability to synthesize compounds means we no longer need fresh animal tissues to extract information about their DNA or 12,000 snails to make a gram of brilliant purple dye. However, as habitats vanish and animals go extinct, biotechnology’s potential to discover and exploit new tools, and new genome sequences, will also diminish. So while we can revel in the discoveries we have already made and trends that show a move away from biopharming, we should remain vigilant about protecting wild nature.
对此有一种解读，可能会让我们对未来和我们剥削的动物的丰富性感到不那么担忧。我们合成化合物的能力意味着我们不再需要新鲜的动物组织来提取它们的 DNA 信息，也不需要 12,000 只蜗牛来制造一克璀璨紫色染料。然而，随着栖息地的消失和动物的灭绝，生物技术发现和开发新工具以及新基因组序列的潜力也将减少。因此，虽然我们可以为已经取得的发现和显示远离生物农业的趋势而欢欣鼓舞，但我们仍然应该时刻警惕保护野生自然。

After all, CRISPR – part of a bacterial defense system that was first adapted into a gene-editing tool in 2012 – was initially discovered by Francisco Mojica, a Spanish researcher, while studying an obscure (and rare) species of archaea called Haloferax mediterranei. When humans destroy ecosystems, they also destroy genetic information that could yield future breakthroughs. Biotechnology is not independent from the natural world – it’s enmeshed within it.
毕竟，CRISPR——一种细菌防御系统的一部分，首次在 2012 年被改编为基因编辑工具——最初是由西班牙研究员弗朗西斯科·莫西卡发现的，当时他正在研究一种名为 Haloferax mediterranei 的稀有古菌。当人类破坏生态系统时，也在破坏可能带来未来突破的遗传信息。生物技术并不是独立于自然界，它深深嵌入其中。