Gene edited mice may halt Lyme disease in Nantucket
A new project to combat Lyme disease is set be trialled in Nantucket, Massachusetts. Thousands of genetically modified mice are to be released on the island, to prevent them from spreading the Lyme bacterium to ticks, which then infect people. This would be the first time that genetically modified animals have been released into the wild, using gene-editing technique CRISPR. The focus would be on finding the genes that prevent some mice from transmitting the Lyme bacterium, then creating and releasing mice with copies of those genes, to create a population of resistant mice. Nantucket has one of the highest rates of Lyme in the US, but its health board isn't convinced, with one official stating "We’re not going to object to him doing his lab work, but we’re a long way from putting his mice on this island.”

NANTUCKET, Mass. — This exclusive summer playground could become the site of an unprecedented experiment to combat Lyme disease by releasing genetically modified mice on the island.

Nantucket boasts some of the highest Lyme infection rates in the country, and the idea unveiled Monday would involve modifying the genes of tens of thousands of mice to keep them from spreading the Lyme bacterium to ticks, which in turn infect people.

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Any release is years away, but an MIT professor presented the idea to the Nantucket board of health and an audience of about 20 residents and scientists, who were broadly favorable.

If the project is realized, it might be the first release into the wild of animals modified with the cutting-edge gene-editing technique CRISPR. Other types of gene-editing have been used, for instance, to make farmed salmon grow faster and to make disease-carrying mosquitoes unable to reproduce.

“This is something new,” said Kevin Esvelt, assistant professor at the MIT Media Lab and the project’s organizer. “We are considering deliberate alteration of the local environment.”

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Lyme disease is a significant problem for residents of Nantucket: The island had the highest rate of Lyme of any county in the US from 1992 to 2001, and finished in third place from 2002 to 2006, according to government data. And Dr. Tim Lepore, a surgeon at a Nantucket hospital who has been seeing patients with Lyme since the ’80s, estimates that many more are infected than the CDC reports. An average year brings about 150 patients to his office, he said, and sometimes twice as many.

Esvelt hopes to reduce the prevalence of Lyme disease by focusing on the white-footed mouse, which is a critical host for Lyme-carrying ticks. Ticks bite the mice, pick up the bacteria, and then transmit it to other mice and to humans. If scientists can stop Lyme from spreading between the mouse and the tick, then they could break the cycle of transmission and Lyme disease rates might plummet.

To accomplish this, Esvelt’s team would first need to find the genes that prevent some mice from transmitting the Lyme bacterium. By creating and releasing mice with multiple copies of those genes, a population of resistant mice could be established. It would take at least a year to have an effect on the tick populations and infection rates, Esvelt predicts.

And Esvelt is a firm believer that such new ventures, which could unilaterally change ecosystems shared by many people, require transparency that science has typically lacked. For this project, Esvelt said that future community meetings might establish a more concrete plan of action, which would involve giving the town full veto power along the way.

“If we don’t change how we do science for this, we will be violating our democratic ideals,” Esvelt told STAT in April.

Audience members listen to a presentation at Monday’s meeting. Kayana Szymczak for STAT

Esvelt said at the meeting that this could first be done on an uninhabited island, and then scaled up to an inhabited island — perhaps Martha’s Vineyard or Nantucket, depending on community preferences.

A potential timeline in Esvelt’s presentation showed that genetically engineered mice might arrive on an uninhabited island in 2020 and in Nantucket in 2023.

Over 100,000 mice might be required for a potential Nantucket operation — groups of 20,000 to 40,000 released every two and a half months, Esvelt said.

If the project on Nantucket is a success, decades down the road, it might lead to an effort to spread these engineered mice over wider swaths of the Northeast. Such an effort would probably rely on the more controversial genetic engineering procedure known as a “gene drive,” which forces a particular genetic trait to spread through the entire population.

The health board’s chair said that the lab work should continue, but that any decisions beyond that are still up in the air.

“No one has made any final decision here,” Malcolm MacNab said. “We’re not going to object to him doing his lab work, but we’re a long way from putting his mice on this island.”

MacNab said that to go forward, he would need to see a detailed plan from Esvelt, including specific points at which the project could be stopped by the community.

The board chair also said that other local groups and regulatory agencies might need to be involved, but he doesn’t yet know who they might be.

One meeting attendee, Danica Connors, an herbalist in Nantucket, said that she was initially skeptical.

“I came here thinking I would say ‘absolutely not,’” Connors said. But, she said, the level of control Esvelt wants to give to the community makes her more comfortable moving forward.

Esvelt felt the meeting gave him the green light to continue. On the way back to Boston, he contacted a collaborator at Tufts University and told him to order mice — their gene hunt was about to begin.