2023年10月2日，诺贝尔奖委员会宣布2023年诺贝尔生物或医学奖授予Katalin Kariko和Drew Weissman，表彰他们在mRNA疫苗研发中的杰出贡献。

祝贺并致敬匈牙利的女生物化学家卡里科（Katalin Karikó）博士！她就是科学界的斗士，科学精神的践行者，人生的楷模！如今回望她这68年人生路，真是每一步都算数，每一步都值得。

1955 年 1 月 17 日，卡里科出生于匈牙利东部小镇小新萨拉什（Kisújszállás）一间烧着木屑炉子的小屋。仔细检查父亲每日屠宰的猪，便是她的科学启蒙课。

1973年，卡里科考入匈牙利名校塞格德大学（University of Szeged），义无反顾地选择了理科。在大学里，她第一次在一场学术报告里听说了信使RNA（mRNA），它携带着DNA中的遗传信息，直接指导蛋白质的合成，承担着“传讯者”的角色。卡里科对这种神奇的分子产生了浓厚的兴趣。1978年，她选择攻读博士学位，重点研究mRNA的应用。

20世纪七十年代，基因工程诞生，不久基因治疗的概念也应运而生，但这些操作均是以DNA为目标，而卡里科却认为mRNA更有前途。毕业后，她选择了进入匈牙利科学院塞格德生物中心（Biological Research Centre, Szeged）生物物理研究所。当时，许多人博士毕业后去美国留学深造，但卡里科对此并不动心，她认为国内同样可以实现自己的愿望。遗憾的是，卡里科这个美好愿望于1985年破灭了，她被单位解雇了。

多年后，卡里科在一次接受采访时曾表示，如果她继续留在匈牙利国内，很有可能成为一个充满抱怨的、平庸的科研人员。无路可退的卡里科不得不重新开始找工作。一开始她想在欧洲找个职位，但最终，她只能远赴大西洋彼岸的费城。在那里，美国天普大学（Temple University）为她提供了一个博士后职位。

没有手机、没有信用卡，夫妇两人带着年仅两岁的女儿，踏上了异国他乡。政府不允许兑换超过100美元的现金，他们就在黑市卖掉了车，把900英镑缝在女儿的泰迪熊里偷偷带出境。卡里科说：“我们没有回头路。我们在那里举目无亲。”

1985年，卡里科在美国天普大学（Temple University）重启科研道路。遗憾的是，首站并不顺利。四年后，她与导师发生了一次冲突，主要原因还是两人对待mRNA观念有差异。像当时的许多科研工作者一样，导师也不看好mRNA的研究。1990年，卡里科加入宾夕法尼亚大学。这时，一项最新进展进一步坚定了她开展mRNA应用的决心。

1990年，威斯康星大学一个研究小组首次将mRNA注射到小鼠体内（doi: 10.1126/science.1690918），并检测到了相应的蛋白表达；两年后，另一个研究小组进一步在大鼠中证明，体外注入的mRNA表达出的蛋白还具有生理活性。如果这两个结果成立，就意味着采用病原体关键蛋白的mRNA，也会产生病毒蛋白，并激发免疫应答，从而发挥疫苗的作用。

这个逻辑推理很容易获得，但是许多科学家对此并不看好。因为这么做存在诸多现实问题，用mRNA做疫苗至少有三大缺陷：稳定性差（目前这个问题依然存在）、体内效率低下和激发机体先天免疫系统（引起严重炎症反应，导致动物立即死亡）。在许多科学家看来，这些困难都是难以逾越的科学鸿沟，尤其是第三个缺陷，可能最终都难以搞定。这种费力不讨好的事情自然没几个人愿意做，再说传统的疫苗制备策略已足足够用，何必舍近求远？

“主流看法”势必会影响一个领域的发展。许多mRNA研究的大牛都退避三舍，不再提起用mRNA做疫苗这码事，领域内默默无闻的新兵遇到的阻力也就可想而知。

进入宾夕法尼亚大学的当年，卡里科就提交了基金申请，想尝试采用mRNA开发疫苗。在这样的主流背景下，申请失败了。然而没想到，随后几年，年年申请，年年被拒，竟达八年无法为这一课题申请到基金。她回忆说，“我每天晚上都在写基金、写基金、写基金，结果每次都被打回来、打回来、打回来。”你有千条妙计，我有一定之规；任你说得天花乱坠，我就不给你基金。这一今天看来并不怎么“大逆不道”的想法，同行专家就是不予通过。2004年诺贝尔化学奖得主赫什科（Avram Hershko）就认为，专家总是墨守成规，许多观点不值得接受（由于泛素加热后仍保持活性，由此他们认定泛素不可能是蛋白质）。

老板们终于看不下去了。1995年，来到宾大的第六年，卡里科迎来了降级降薪。她回忆到，她当时刚刚做出一些重要的发现，学校把她轰出了实验室，在动物房边上给她安排了一个小房间办公做实验。更惨的是，这个节骨眼，她又被诊断出癌症，需要进行两次手术，而她的丈夫由于签证问题不得不滞留在匈牙利，长达半年无法返美。她只能一边接受治疗，一边照顾孩子。

一般人有此遭遇，早就离开学术界了，但卡里科还是熬了下来：“我想过去别的地方，研究别的东西。我还想过可能是我不够优秀，不够聪明。我努力说服自己：万事已经俱备，我只需要把实验做得更漂亮就行了。”

幸运的是，卡里科最终康复了，并继续开展自己的实验。由于各方限制，做事可谓举步维艰。没经费订杂志，为了看到最新的论文，她还得去复印。在1997年一次复印时，卡里科结识了刚到宾大不久的免疫学家韦斯曼（Drew Weissman）。韦斯曼对卡里科的想法很感兴趣，决定资助她继续开展研究，她的项目也正式成为“韦斯曼-卡里科项目”。卡里科当时的境遇可说降到了冰点，待遇比技术员都要低，韦斯曼的帮助可谓是雪中送炭，不仅仅是资金支持，同样重要的还有精神鼓励。

卡里科的研究逐渐有所起色。1998年，期盼已久的基金终于得到批复，尽管只有区区10万美元，但至少是一个好的开始。第二年，又获得100万美元资助。卡里科和韦斯曼商讨后达成一致——需要首先解决mRNA应用的安全性问题，也就是理解mRNA诱发机体炎症反应的原因。

上世纪九十年代，先天免疫机制的阐明拓展了人们对免疫系统的认识。1998年，美国免疫学家巴特勒（Bruce Beutler）发现树突细胞等免疫细胞的表面存在Toll样受体 (TLR) 家族，能识别细菌成分（如脂多糖），两者结合就会激活并启动先天免疫应答，巴特勒也因为这一发现分享2011年诺贝尔生理学或医学奖。

卡里科推测，mRNA注射到动物体内诱发炎症，可能是因为它们可被TLR分子识别。为验证自己假说的正确性，卡里科首先建立一个体外系统模拟炎症反应，应用人工合成的mRNA直接处理细胞，确实激活了免疫应答，释放出大量免疫因子。进一步研究发现，多种TLR分子（包括TLR7,8等）确实可以识别体外注入的mRNA。

2004年，卡里科完成了一个关键实验。她从哺乳动物和细菌中直接提取mRNA，并用它们处理细胞，结果发现哺乳动物mRNA基本不激活免疫应答 (线粒体mRNA除外)，而细菌mRNA则诱导细胞因子的释放，这一结果说明，诱发免疫应答的原因不在mRNA本身，而应该在其结构差异。当时已知，哺乳动物mRNA存在广泛的碱基修饰现象，而细菌等原核生物则通常不存在这一现象（与体外合成的mRNA类似）。于是，卡里科对体外合成的mRNA也进行了碱基修饰，结果使免疫应答能力大大减弱（后来动物实验也证明修饰后的mRNA不再产生严重炎症反应）。其实，哺乳动物识别非修饰mRNA（外源物成分），但对修饰mRNA视而不见的能力恰恰是免疫系统的基本特征——区分“非我”，也是机体对自身的保护。这一发现意味着，mRNA体内应用的安全性得到了有效解决（通过体外碱基修饰来实现）。

卡里科进一步研究还发现，体外合成的mRNA通常会污染一定量的双链RNA，而双链RNA也会引发免疫应答，因此她对最初合成的RNA进行纯化，除去双链RNA。这种操作一方面减少了炎症发生，更重要的是极大增加了mRNA在体内的蛋白生成效率，从而解决mRNA应用过程中效率低下的难题。卡里科共发表70多篇论文，绝大多数聚焦于mRNA体外制备方法的改进和完善，解决实际应用过程中面临的诸多问题。

2006年，卡里科和韦斯曼申请了第一个mRNA相关专利——含修饰核苷酸的mRNA制备及应用，主要涉及无免疫原性、包含核苷酸修饰等特性的mRNA（专利号：US 8278036）。迄今为止，她已拥有十几个专利，全部围绕着mRNA制备方法的改进、实用化操作和应用。当年，她与人和合作共同成立了一家生物技术公司——RNARx，尝试开发mRNA药物（主要开发治疗贫血的EPO mRNA），但公司最终于7年后关闭。卡里科期望的mRNA应用热潮并未出现，市场对这项研究并不热衷，因此也少人问津。

2010年，转机再次出现。正在斯坦福大学做博士后的罗西（Derrick Rossi）发现了卡里科的文章，并敏锐意识到这一方法的巨大应用潜力。他成立了一家生物技术公司——也就是Moderna，应用mRNA开发疫苗和药物。与此同时，卡里科也将自己的技术转让给德国一家新兴生物技术公司BioNTech。彼时，BioNTech还蜗居在德国美因茨大学（Mainz university）的校园内，连公司网站都没做起来。

2013年，卡里科与宾夕法尼亚大学又发生一次不愉快，校方拒绝恢复她1995年降薪的教师职位，又在知识产权许可上与她产生分歧（宾大将知识产权卖给了另一家公司）。最终，卡里科选择辞职，加入BioNTech并担任高级副总裁。校方对卡里科极尽刻薄，称BioNTech是一家连网站都不存在、名不见经传的小公司，暗示卡里科的选择毫无价值。

随着mRNA技术在应用过程中的进一步改进，两家公司距离真正的市场成功越来越近。2017年，Moderna开始开发寨卡病毒mRNA疫苗；2018年，BioNTech与辉瑞公司合作开发流感mRNA疫苗，尝试从实验室走向应用。但市场仍不买账，投资者对mRNA疫苗应用前景并不看好，两家公司只能 “艰难度日”。

在这沉默苦闷的研究岁月中，比卡里科出名更早的是她的女儿祖萨娜·弗朗西亚（Zsuzsanna Francia）。也许是继承了母亲坚忍不拔的精神，祖萨娜在2008年北京奥运会和2012年伦敦奥运会上连续夺得了划船比赛冠军。

2020年初，新冠肺炎暴发，新冠病毒蔓延全球。

1月11日，中国疾控中心张永振研究团队在病毒学网站（virological.org）公布了新型冠状病毒全基因组序列。

序列刚刚公开，欧美的制药公司就开始研究mRNA疫苗将要使用的序列。

1月13日，序列确定，Moderna开始制作mRNA。

后来的事情，我们都知道了。

在全球多国参与的新冠疫苗开发竞赛中，mRNA疫苗的优势（研发时间短）充分体现，在得到新冠病毒刺突蛋白（S）mRNA信息基础上，快速开启设计、制备、动物实验、临床实验等步骤。11月9日，辉瑞与BioNTech联合宣布，基于Ⅲ期临床结果，其研发的新冠疫苗mRNA BNT162b2有效率超过90%（最终数据显示有效率可达95%）；一周后，Moderna宣布，其开发的mRNA疫苗mRNA-1273有效率也接近95%。

当卡里科听到BioNTech三期临床振奋人心的结果后，她的第一反应是：“得救了！我拼命地吸气，我太兴奋了，我真怕我死了……”悬了许久的心终于可以得到些许休息。卡里科希望mRNA疫苗能在随后新冠肺炎预防方面发挥重要作用，并期望mRNA技术能在更多疾病治疗方面得到广泛应用。

现在已经是哈佛大学干细胞研究所教授的罗西认为，如果mRNA疫苗最终在新冠肺炎疫情方面发挥了关键性作用，卡里科和韦斯曼绝对配得上诺贝尔化学奖。

此时距卡里科最初开始研究mRNA已有四十多年，距离她的关键技术突破也有了19年了。

Press release

2023-10-02

The Nobel Assembly at Karolinska Institutet

has today decided to award

the 2023 Nobel Prize in Physiology or Medicine

jointly to

Katalin Karikó and Drew Weissman

for their discoveries concerning nucleoside base modifications that enabled the development of effective mRNA vaccines against COVID-19

The discoveries by the two Nobel Laureates were critical for developing effective mRNA vaccines against COVID-19 during the pandemic that began in early 2020. Through their groundbreaking findings, which have fundamentally changed our understanding of how mRNA interacts with our immune system, the laureates contributed to the unprecedented rate of vaccine development during one of the greatest threats to human health in modern times. 

Vaccines before the pandemic

Vaccination stimulates the formation of an immune response to a particular pathogen. This gives the body a head start in the fight against disease in the event of a later exposure. Vaccines based on killed or weakened viruses have long been available, exemplified by the vaccines against polio, measles, and yellow fever. In 1951, Max Theiler was awarded the Nobel Prize in Physiology or Medicine for developing the yellow fever vaccine.

Thanks to the progress in molecular biology in recent decades, vaccines based on individual viral components, rather than whole viruses, have been developed. Parts of the viral genetic code, usually encoding proteins found on the virus surface, are used to make proteins that stimulate the formation of virus-blocking antibodies. Examples are the vaccines against the hepatitis B virus and human papillomavirus. Alternatively, parts of the viral genetic code can be moved to a harmless carrier virus, a “vector.” This method is used in vaccines against the Ebola virus. When vector vaccines are injected, the selected viral protein is produced in our cells, stimulating an immune response against the targeted virus.

Producing whole virus-, protein- and vector-based vaccines requires large-scale cell culture. This resource-intensive process limits the possibilities for rapid vaccine production in response to outbreaks and pandemics. Therefore, researchers have long attempted to develop vaccine technologies independent of cell culture, but this proved challenging.

Figure 1. Methods for vaccine production before the COVID-19 pandemic. © The Nobel Committee for Physiology or Medicine. Ill. Mattias Karlén

mRNA vaccines: A promising idea

In our cells, genetic information encoded in DNA is transferred to messenger RNA (mRNA), which is used as a template for protein production. During the 1980s, efficient methods for producing mRNA without cell culture were introduced, called in vitro transcription. This decisive step accelerated the development of molecular biology applications in several fields. Ideas of using mRNA technologies for vaccine and therapeutic purposes also took off, but roadblocks lay ahead. In vitro transcribed mRNA was considered unstable and challenging to deliver, requiring the development of sophisticated carrier lipid systems to encapsulate the mRNA. Moreover, in vitro-produced mRNA gave rise to inflammatory reactions. Enthusiasm for developing the mRNA technology for clinical purposes was, therefore, initially limited.

These obstacles did not discourage the Hungarian biochemist Katalin Karikó, who was devoted to developing methods to use mRNA for therapy. During the early 1990s, when she was an assistant professor at the University of Pennsylvania, she remained true to her vision of realizing mRNA as a therapeutic despite encountering difficulties in convincing research funders of the significance of her project. A new colleague of Karikó at her university was the immunologist Drew Weissman. He was interested in dendritic cells, which have important functions in immune surveillance and the activation of vaccine-induced immune responses. Spurred by new ideas, a fruitful collaboration between the two soon began, focusing on how different RNA types interact with the immune system.

The breakthrough

Karikó and Weissman noticed that dendritic cells recognize in vitro transcribed mRNA as a foreign substance, which leads to their activation and the release of inflammatory signaling molecules. They wondered why the in vitro transcribed mRNA was recognized as foreign while mRNA from mammalian cells did not give rise to the same reaction. Karikó and Weissman realized that some critical properties must distinguish the different types of mRNA.

RNA contains four bases, abbreviated A, U, G, and C, corresponding to A, T, G, and C in DNA, the letters of the genetic code. Karikó and Weissman knew that bases in RNA from mammalian cells are frequently chemically modified, while in vitro transcribed mRNA is not. They wondered if the absence of altered bases in the in vitro transcribed RNA could explain the unwanted inflammatory reaction. To investigate this, they produced different variants of mRNA, each with unique chemical alterations in their bases, which they delivered to dendritic cells. The results were striking: The inflammatory response was almost abolished when base modifications were included in the mRNA. This was a paradigm change in our understanding of how cells recognize and respond to different forms of mRNA. Karikó and Weissman immediately understood that their discovery had profound significance for using mRNA as therapy. These seminal results were published in 2005, fifteen years before the COVID-19 pandemic.

Figure 2. mRNA contains four different bases, abbreviated A, U, G, and C. The Nobel Laureates discovered that base-modified mRNA can be used to block activation of inflammatory reactions (secretion of signaling molecules) and increase protein production when mRNA is delivered to cells.  © The Nobel Committee for Physiology or Medicine. Ill. Mattias Karlén

In further studies published in 2008 and 2010, Karikó and Weissman showed that the delivery of mRNA generated with base modifications markedly increased protein production compared to unmodified mRNA. The effect was due to the reduced activation of an enzyme that regulates protein production. Through their discoveries that base modifications both reduced inflammatory responses and increased protein production, Karikó and Weissman had eliminated critical obstacles on the way to clinical applications of mRNA.

mRNA vaccines realized their potential

Interest in mRNA technology began to pick up, and in 2010, several companies were working on developing the method. Vaccines against Zika virus and MERS-CoV were pursued; the latter is closely related to SARS-CoV-2. After the outbreak of the COVID-19 pandemic, two base-modified mRNA vaccines encoding the SARS-CoV-2 surface protein were developed at record speed. Protective effects of around 95% were reported, and both vaccines were approved as early as December 2020.

The impressive flexibility and speed with which mRNA vaccines can be developed pave the way for using the new platform also for vaccines against other infectious diseases. In the future, the technology may also be used to deliver therapeutic proteins and treat some cancer types.

Several other vaccines against SARS-CoV-2, based on different methodologies, were also rapidly introduced, and together, more than 13 billion COVID-19 vaccine doses have been given globally. The vaccines have saved millions of lives and prevented severe disease in many more, allowing societies to open and return to normal conditions. Through their fundamental discoveries of the importance of base modifications in mRNA, this year’s Nobel laureates critically contributed to this transformative development during one of the biggest health crises of our time.

Key publications

Karikó, K., Buckstein, M., Ni, H. and Weissman, D. Suppression of RNA Recognition by Toll-like Receptors: The impact of nucleoside modification and the evolutionary origin of RNA. Immunity 23, 165–175 (2005).

Karikó, K., Muramatsu, H., Welsh, F.A., Ludwig, J., Kato, H., Akira, S. and Weissman, D. Incorporation of pseudouridine into mRNA yields superior nonimmunogenic vector with increased translational capacity and biological stability. Mol Ther 16, 1833–1840 (2008).

Anderson, B.R., Muramatsu, H., Nallagatla, S.R., Bevilacqua, P.C., Sansing, L.H., Weissman, D. and Karikó, K. Incorporation of pseudouridine into mRNA enhances translation by diminishing PKR activation. Nucleic Acids Res. 38, 5884–5892 (2010).

Katalin Karikó was born in 1955 in Szolnok, Hungary. She received her PhD from Szeged’s University in 1982 and performed postdoctoral research at the Hungarian Academy of Sciences in Szeged until 1985. She then conducted postdoctoral research at Temple University, Philadelphia, and the University of Health Science, Bethesda. In 1989, she was appointed Assistant Professor at the University of Pennsylvania, where she remained until 2013. After that, she became vice president and later senior vice president at BioNTech RNA Pharmaceuticals. Since 2021, she has been a Professor at Szeged University and an Adjunct Professor at Perelman School of Medicine at the University of Pennsylvania.

Drew Weissman was born in 1959 in Lexington, Massachusetts, USA. He received his MD, PhD degrees from Boston University in 1987. He did his clinical training at Beth Israel Deaconess Medical Center at Harvard Medical School and postdoctoral research at the National Institutes of Health. In 1997, Weissman established his research group at the Perelman School of Medicine at the University of Pennsylvania. He is the Roberts Family Professor in Vaccine Research and Director of the Penn Institute for RNA Innovations.

Illustrations: © The Nobel Committee for Physiology or Medicine. Illustrator: Mattias Karlén

The Nobel Assembly, consisting of 50 professors at Karolinska Institutet, awards the Nobel Prize in Physiology or Medicine. Its Nobel Committee evaluates the nominations. Since 1901 the Nobel Prize has been awarded to scientists who have made the most important discoveries for the benefit of humankind.

Nobel Prize® is the registered trademark of the Nobel Foundation

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