Scientists have a bold idea to fight Lyme disease: Change the mice | 60 Minutes Archive
In a Nutshell
Scientists are developing genetically engineered white-footed mice that carry a heritable Lyme-resistance antibody, aiming to break the disease transmission cycle by making ticks that feed on mice unable to acquire the bacteria. The approach targets Nantucket, where Lyme affects 15% of residents, with engineered mice planned for gradual release after community consent and ecological testing on a private island. The project represents the first attempt to use CRISPR-based gene editing to permanently alter a wild population's immunity, requiring both regulatory approval and local democratic decision-making before any field deployment.
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Biologist Charles Darwin began crafting his theory of evolution on a trip to the Galapagos Islands, where he discovered animals had developed unique traits that varied from island to island. Nearly two centuries later, on a different island, scientists aren't just observing evolution, they now have the technology to shape it. This past year, a team of modern-day Darwins on Nantucket are hoping to use genetic engineering to reduce the transmission of Lyme disease, a tick-borne illness found primarily in the Northeast and Upper Midwest, but also throughout the United States. The scientists' target is not the deer often associated with the disease or even the ticks, but wild mice, the main carriers of Lyme. It's a first-of-its-kind approach, where scientists and locals are working together to decide whether to sculpt evolution.
30 miles off the coast of Cape Cod, Massachusetts, is the island of Nantucket, a 14-mile long, 3-mile wide oasis known for its natural beauty, pristine shorelines, and protected landscape. A scourge has afflicted 15% of its residents. The natural disaster in the area is not hurricanes or tornadoes or earthquakes, it is Lyme disease. It is the one plague that might be severe enough that communities might want to engineer a wild organism in order to get rid of it, or at least reduce the level a lot.
Last October, deep in the island's brush, MIT associate professor Kevin Esvelt, a pioneer in genetic engineering, was waving a white flag in search of ticks. These tiny vectors of Lyme disease were not hard to find. These are the big ones because these are largely adults. Nymphs are often poppy seed sized. Esvelt's collaborator is Sam Telford, an epidemiologist at Tufts University who's been studying ticks on Nantucket for the last 40 years. There's a 50% chance, maybe more, that a tick is actually carrying Lyme disease. These guys will swell up 50 to 100 times that size with blood when engorged.
The scientists are interested in wild mice. This is a wild white-footed mouse. Telford is tracking the mouse population on Nantucket as part of a novel project. The scientists want to use genetic engineering to interrupt the cycle of infection necessary for Lyme disease to flourish. White-footed mice are the main host of Lyme bacteria. When an uninfected tick bites an infected mouse, the bacteria transfer to the tick. When that infected tick then bites an uninfected mouse, the cycle continues. Deer don't get infected, but they help spread the disease because ticks embed on them to feed, then reproduce, with a single female tick laying as many as 2,000 eggs.
Esvelt and Telford's big idea is to change the genetic makeup of the mice so they're immune to Lyme. That way, the ticks that bite them won't get infected. You don't have to kill the mouse in order to interrupt the cycle. It'd be so much more economical and straightforward to just go out and poison all the mice, right? Get rid of the mice. But then there's a whole food chain that might depend on these mice that would be impacted. The dream is that we can use new technologies to ensure that wild creatures can live in peace playing their normal ecological role, but without causing disease that make people suffer.
80-year-old Dr. Timothy Lepore might finally be able to retire if Esvelt's dream becomes a reality. Over the past 40 years he's been the island's emergency room head, sole surgeon, even its medical examiner. Today Dr. Lepore runs the only private practice on Nantucket, where he treats dozens of patients with Lyme disease each year. Being in private practice, it is while not well paid it's in like chickens and donuts and prefer lobsters, actually. Lyme disease can be treated with antibiotics, but if left untreated, the infection can spread to the heart, joints, and nervous system.
33-year-old Shauna Asplint's body hurts all the time. She doesn't know if that's from her Lyme disease or what. Her neck is stiff, her ankles are sore and her hips. Asplint was first diagnosed with Lyme when she was 10 years old. A few years later, the left side of her face stopped moving. A residual effect from the disease is still noticeable today. It's still a little off and then if she raises her eyebrows, it just doesn't move. We see people with facial policies. We see little kids with swollen knees. We see people with Lyme rashes. So, it alters people's behavior and activities.
The problem on Nantucket can be traced back to 1926, when locals voted to import two female deer to the island to give a lone buck company. As the deer population grew, so did the ticks. On top of that, by the 1950s, half the land on the island was put into conservation. The untamed brush and wild grasslands create an ideal ecosystem for Lyme's host to thrive. We have a problem with tick-borne disease because we engineered the environment to maximize the number of ticks and maximize the number of mice that are the best host of Lyme disease. And it came back and bit us. Literally.
A trip at age 11 to the Galapagos Islands sparked Esvelt's lifelong obsession with evolution. In 2013, he was the first to propose that CRISPR, a revolutionary technology that enables scientists to edit DNA, could be used to change a species genetics in perpetuity, hacking the laws of inheritance. This idea led to the project they call Mice Against Ticks in the Sculpting Evolution Lab Esvelt runs at MIT.
For the last 9 years, Esvelt and researcher Joanna Buchthal have been studying whether they could add a gene for an antibody that prevents Lyme infection to a mouse embryo that has progressed into two cells. Their technique involves injecting both cells to maximize the likelihood that they get the antibody gene in their DNA. The injection mix contains both the antibody gene and CRISPR, which acts like molecular scissors. After CRISPR finds and cuts the targeted area of DNA, the cell inserts the gene into the mouse's genetic code. When this mouse is born, it will be immune to Lyme disease. And so will its children.
If someone gets a polio vaccine, their kids aren't going to be immune to polio unless they get the vaccine, too. This is a heritable immunization. We're encoding immunity so that that immunity is passed on generationally. And every mouse that gets the antibody gene is actually immune. We are absolutely speeding up evolution, and that's precisely why we have to be careful because we are doing things that couldn't happen naturally.
The plan is to release thousands of engineered mice on Nantucket over time, starting during the winter months when the native mouse population is low. But first, Esvelt needs community buy-in. He chose Nantucket not only for its high rate of Lyme, but also for its tight-knit, well-educated community with a tradition of town hall democracy. For the 10th time, the scientists presented their latest findings to locals: So it appears that we have indeed produced the first hereditarily Lyme immune laboratory mice capable of breaking the disease transmission cycle.
We have a huge population of field mice here. Shall we expect a live year population? Having had Lyme disease twice, I thought what a cool idea. But mice are kind of the foundation of the food chain. So tinkering with the food chain makes me a little cautious. How long before it's actually going to take effect and keep me from getting Lyme disease again? Some people are really gung-ho about this. Some people have deep reservations, but what I found heartening about this in Nantucket in particular is that pretty much everyone agrees that this is how we should go about developing these kinds of technologies. That it should not just be scientists in their laboratories get a clever idea, and then boom, it's there.
Dr. Timothy Lepore says he's supportive of the proposal. But as an avid falconer, he wants testing to be done to ensure there won't be unintended consequences to the island's ecosystem. Could a change in the field mouse lead to a change in the hawk? Well, that's the question. I don't think so. But we don't know. That has to be shown. Do you worry about fooling around with Mother Nature? Absolutely. But on the other hand, I'm not terribly fond of Mother Nature if she's going to give my kids disease. All of technology is saying to Mother Nature, "You're beautiful and we appreciate you very much and we need to conserve you, but we're not always happy with the way things work naturally and so we're going to change it."
This is different because it's hard for individuals to opt out. And I think that means we need to do the science differently because we need to ensure that people have a voice early enough to actually influence the direction that the technology is developed. If federal and state regulators agree, the team plans to first release the engineered mice in a small field trial on a private island so they can better understand the ecological impacts before any potential experiments on Nantucket. I think it's a field trial that works. It's something that allows us to dramatically reduce the fraction of ticks that are infected. That doesn't have anything obviously go wrong with the ecosystem. And then the community has a good discussion and then they decide. And I think there's benefits as we discussed even if they say no. And then we walk away.
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