Pitt scientists Tim Hand (left) and Vaughn Cooper (right), among 38 co-authors, urge the scientific community to halt the development of mirror bacteria and engage in global discussions to shape a proactive path forward. Cooper emphasizes that while the risks are not imminent, early dialogue is crucial to addressing potential threats before they materialize.
Vaughn Cooper, professor of microbiology and molecular genetics, and Tim Hand, associate professor of pediatrics and of immunology, both School of Medicine, are part of a global team of researchers that published new findings in Science on potential risks from the development of mirror bacteria—synthetic organisms in which all molecules have reversed chirality (i.e. are “mirrored”).
Scientists have begun early work toward creating mirror bacteria, and while the capability is at least a decade away, recent years have seen significant progress. The new paper finds that, if created, these organisms may pose significant dangers to human, animal, plant and environmental health. The authors call for a broad conversation among scientists, policymakers and a wide range of other stakeholders to chart a path toward a better understanding and mitigation of potential risks from mirror bacteria.
“This form of life has never existed or evolved,” Cooper said. “Consequently, all biological interactions would be different or likely wouldn’t work. A synthesized mirrored microbe wouldn’t just be just essentially invisible to animals and likely plants, but also other microbes, including viruses that could attack and kill it.”
Alongside Cooper and Hand are 36 authors from various countries, including leading experts in immunology, plant pathology, ecology, evolutionary biology, biosecurity and planetary sciences. The publication in Science is accompanied by a detailed 300-page technical report.
While there is no imminent threat, the Science paper finds that mirror bacteria may pose serious risks. Immune defenses in humans, animals and plants rely on recognizing specific molecular shapes found in invading bacteria. If these shapes were reflected—as they would be in mirror bacteria—recognition would be impaired and many basic immune defenses could fail, potentially leaving organisms vulnerable to infection.
The analysis also suggests that mirror bacteria in the environment may be able to evade natural predators like phages and protists, which rely heavily on chirally mediated interactions to kill bacteria and limit their populations. Transport via animals and humans could enable spread between diverse ecosystems. Persistent and widespread environmental populations of mirror bacteria would expose humans, animals and plants to an ongoing risk of infection—a serious threat to humans and to global ecosystems.
The authors call for further scrutiny of their findings and conclude that, unless compelling evidence emerges that these organisms would not pose extraordinary dangers, mirror bacteria should not be created. Notably, the group includes several authors who previously held the creation of mirror bacteria as a long-term aspirational goal.
“It would require enormous effort to build such an organism,” Cooper said. “But we must stop that progress and have an organized, inclusive dialogue about how to effectively govern this. There is some exciting science that will be born because of these technologies that we want to facilitate. We don’t want to limit that promise of synthetic biology, but building a mirror bacterium is not worth the risk.”
This paper marks a starting point for a broader discussion about the risks from mirror bacteria, including participation from the global scientific community, policymakers, research funders and other stakeholders. Several of the authors on the paper are involved in planning a series of events throughout 2025, including events planned at the Institut Pasteur in France, the University of Manchester in the U.K. and the National University of Singapore, to scrutinize the findings of the paper and discuss steps that can be taken to prevent risks from mirror bacteria.
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Cooper Q&A
by Kat Procyk
Vaughn Cooper, professor of microbiology and molecular genetics, School of Medicine, is a co-author on a recent publication in Science that urges scientists to cease all research on mirror bacteria and invites the community to participate in a global discussion that examines the risks they could present and how to avoid them.
What are mirror bacteria?
Cooper: Mirror bacteria would be synthesized organisms in which all their molecules are reversed. These organisms don’t exist and have never existed, but it’s been a long-term goal of a few scientists to bring them into creation. There’s been significant movement in this area of research in the last few years, but the actual creation of a mirror bacteria would be at least a decade, possibly several, away.
The notion of mirrored life goes back decades, but only a select few that are really accomplished and imaginative have been able to make any kind of progress on the foundational technology needed to develop mirror bacteria. Many of them now welcome a new path forward to understanding mirror life and the risks it could pose.
What is the threat of mirror bacteria?
Cooper: Before digging further, our team of scientists was skeptical—myself included—of the risks that these synthetic organisms could pose. We learned that if they’re successfully created—which would require an enormous effort—mirror bacteria would likely be able to invade many human, plant and animal immune system responses, possibly leading to widespread, lethal infections in multiple species.
In the natural world, viruses and other microbes keep these systems in check. But mirror bacteria, because of their reversed structure, would likely be able to evade immune defenses and natural predators, potentially establishing themselves in a wide range of ecosystems.
When my co-authors and I came to this conclusion, we reached out to other experts to find fault with our hypothesis and concerns, which is a great example of how science should work. None of us were able to find a critical flaw in what we discovered, and that’s why we’re emphasizing the need to reevaluate how to move forward with this research.
What are the consequences of stopping research into mirror bacteria?
Cooper: Building an organism like this is still at least a decade away, but research towards it has been underway. It’s vital we start a conversation about whether that continues.
From my perspective, there aren’t really any practical benefits to mirror bacteria, so ceasing this work would have very little effect on other research. Research on mirror-image nucleic acids and proteins that could help targeted therapies or new drug delivery systems will be able to continue.
Now that we know about this problem, how can scientists move forward?
Cooper: There’s an opportunity here that we didn’t have before. Discussing it now allows us to consider and prevent the risks of mirror bacteria long before they’re realized.
At this moment, we are urging the scientific community to no longer pursue research with the goal of creating mirror bacteria, as well as encouraging funders to make clear they won’t support this work.
We’re inviting the global scientific community to attend a series of events to further examine the risks and explore promising ways to avoid them. By making this a global effort, we’re far ahead of this ever becoming a problem.
There’s nothing we have to fear today. We should be celebrating the imagination and collaborative process involved. I have particular admiration for my co-authors on this project who previously had a long-term aspiration to create mirror bacteria but moved away from that goal. I think it’s inspiring to scientists young and old to see that spirit of collaboration and humility in action.
Read more in The New York Times, Financial Times, The Guardian and Science.