• Some scientists trying to create "mirror life" have stopped in their tracks.
• A mirror microorganism could end up being a major pathogen since our immune systems wouldn't notice it.
• Mirror-image biology inverts a fundamental property of life on Earth: which way molecules point.

Creating "mirror life" could be one of science's greatest breakthroughs, but some researchers who began the effort are now calling for it to stop.

No mirror-life microorganisms exist yet. However, 38 scientists warned in a paper published in the journal Science on December 12 that if someone created one and it escaped the lab, it could cause a catastrophic multi-species pandemic.

"We're basically giving instructions of how to make a perfect bioweapon," Kate Adamala, a co-author of the paper and a chemist who leads a synthetic biology lab at the University of Minnesota, told Business Insider.

As the risks became clear, Adamala ended her lab's efforts toward building a mirror cell. Her multi-year grant for that facet of their research expired and she decided not to apply for renewal, she said.

Now she's urging other scientists to do the same, along with the 37 other researchers.

"Although we were initially skeptical that mirror bacteria could pose major risks, we have become deeply concerned," they wrote in the paper.

What is mirror life?

Mirror biology takes a fundamental rule of life on Earth, called chirality, and flips it.

Chirality is the simple fact that molecules — like sugars and amino acids — point in one of two directions. They are either right-handed or left-handed.

For some reason, though, life will only use one chiral form of each molecule. DNA, for example, only uses right-handed sugars for its backbone. That's why it twists to the right.

In mirror biology, scientists aim to create living cells where all the chirality is flipped. Where natural life uses a right-handed peptide, to build proteins, mirror life would use the same peptide in its left-handed form.

Adamala's research was focused on making mirror peptides, which can help create longer-lasting pharmaceuticals.

A full mirror cell was the long-term goal of that research. Mirror cells could help prevent contamination in bioreactors that use bacteria for green chemical manufacturing because, in theory, they wouldn't interact with natural microorganisms.

"You could have this perfect bioreactor that can just sit there and you can stick your finger into it and you're not going to contaminate it," Adamala said. "That's also precisely the problem."

A mirror bacteria could bypass the natural checks and balances of life, like competing with other bacteria or battling our immune systems.

Immune systems would ignore mirror cells

Adamala said "the death sentence" for her mirror-cell research came when she spoke to immunologists. They explained that for humans, other animals, and plants, immune system activation depends on chirality.

Immune cells recognize pathogens' proteins, but they wouldn't detect the inverse versions of those proteins that mirror cells would use.

A mirror pathogen "doesn't interact with the host. It just uses it as a warm incubator with a lot of nutrients," Adamala said.

If a mirror bacteria escaped the lab, it could cause slow, persistent infections that can't be treated with antibiotics (because those, too, rely on chirality).

Because they wouldn't face any immune resistance, mirror bacteria wouldn't need to specialize in infecting corn, or goats, or birds.

"It would be a disease of anything that lives that can be infected," Adamala said.

In the worst-case scenario, a mirror bacteria would multiply endlessly, unfettered. It would take over its hosts and eventually kill them. It would destroy crops. It would have no predators. It would overwhelm entire ecosystems, swapping out portions of our natural world for a new mirror world.

A long way away

Ting Zhu, one of the leading researchers trying to make a mirror cell, told BI in an email that he supports being cautious but doesn't think "a complete mirror-image bacterium can be synthesized in the foreseeable future."

Zhu leads a mirror-image biology lab at Westlake University in China. He was not involved in the Science paper.

Adamala estimates that the world's first mirror bacteria is still about a decade away. She argues that's exactly why the research should stop now before it builds all the tools that someone could use to make that final leap.

"No one can do it on their own right now," Adamala said. "The technology is not mature enough, which means we're pretty well safeguarded against someone crazy enough to say, 'I'll just go do it.'"

In the meantime, Adamala and the other paper authors invited more research and scrutiny on the risks they've identified.

"If someone does prove us wrong, that would make me really happy," she said.

Recently, Congress' Select Subcommittee on the Coronavirus Pandemic released its final report. The basic gist is about what you'd expect from a Republican-run committee, in that it trashes a lot of Biden-era policies and state-level responses while praising a number of Trump's decisions. But what's perhaps most striking is how it tackles a variety of scientific topics, including many where there's a large, complicated body of evidence.

Notably, this includes conclusions about the origin of the pandemic, which the report describes as "most likely" emerging from a lab rather than being the product of the zoonotic transfer between an animal species and humans. The latter explanation is favored by many scientists.

The conclusions themselves aren't especially interesting; they're expected from a report with partisan aims. But the method used to reach those conclusions is often striking: The Republican majority engages in a process of systematically changing the standard of evidence needed for it to reach a conclusion. For a conclusion the report's authors favor, they'll happily accept evidence from computer models or arguments from an editorial in the popular press; for conclusions they disfavor, they demand double-blind controlled clinical trials.

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