Proposal For Genetically Engineered Mice To Fight Lyme Disease On Nantucket Gets Another Look

After a recent scientific breakthrough, MIT researchers were back on Nantucket this week to provide an update on their radical proposal to combat Lyme disease on the island by releasing thousands of genetically-engineered white-footed mice to break the cycle of infection.

And they didn’t come alone. Along for the ride was a 60 Minutes camera crew and CBS’ chief medical correspondent Jon LaPook, as the program is planning an upcoming segment on the so-called “mice against ticks” proposal.

Addressing the Select Board Wednesday night, MIT biologist Kevin Esvelt, along with researcher and graduate student Joanna Buchthal and tick researcher Sam Telford, shared that they had successfully created the first genetically-modified mouse resistant to Lyme disease, and that its immunity was passed down to subsequent generations. They accomplished this by taking an anti-Lyme antibody and inserting it into the genome of a lab mouse.

Read MIT's Presentation Slides

“For years, everything we tried failed,” Buchthal said, describing how a new approach helped her team to generate embryos for the experiment by tracking mouse ovulation cycles using their body temperature. “We were able to overcome a major bottleneck for the project.”

The goal, she said, is to make Lyme-immune mice to prevent ticks from getting Lyme disease, thus breaking the cycle of infections and reducing the number of cases on Nantucket, which has the highest incidence rate in the country. With its recent breakthrough, Esvelt and Buchthal are almost ready to being field trials, which would be the precursor to any potential project on Nantucket. Such a field trial would likely take place on a small private island somewhere off the coast of New England. 

"No one has previously engineered a wild animal with the intention of releasing it into the environment and having the new trait stay there for many years," Esvelt said. "That's never been done before, which means there's going to be a lot of regulatory scrutiny of it."

Nantucket’s resident tick expert, Dr. Tim Lepore, was also in attendance at Wednesday's Select Board meeting. While he didn’t speak, Lepore previously told the Current that he supports the project primarily because other efforts to reduce the incidence of tick-borne diseases have failed. People won’t take simple precautions like regular tick checks after being outdoors, he said, and initiatives to bring down the island’s deer population through an extended hunt have also been met with resistance.

A field trial for the "mice against ticks" project would still need to be approved by federal regulators.

“Once the federal regulatory agencies approve an initial field trial, then the mice would be introduced onto this island, and we would then see what happens to all of the different organisms on this island,” Esvelt added. “But the other reason we're here is we want this to be a community-guided project throughout. That's why we came here before we did anything in the laboratory, and we want that to continue throughout the process. So if anyone in the community has something that you particularly want to be scrutinized carefully in this field trial, then you still probably have a couple of years, given the regulatory timing, but we want to hear from you. We want to hear from you because you live here and we don't live here, and that means that you have probably spotted something, or might think of something that we haven't thought of. And so we want to hear it from you.”

A number of residents asked questions regarding the impact on predators that eat mice, such as hawks, and how the mice would be distributed on the island if the project eventually moves forward.

“One of the things we heard from the community of Nantucket is that a lot of folks here said we don't want antibodies from other species in our white-footed mice,” Esvelt said. “So what's going to go in the white-footed mice is, in fact, antibodies from vaccinated white-footed mice, and once we have those, the idea is that because all white-footed mice out there in the wild have antibodies, just like we have antibodies when we get infected with something, our immune systems respond by making antibodies. And when a white-footed mouse gets infected with Lyme disease, it will also develop antibodies against the Lyme bacteria. So the idea is to ensure that we are only putting something in all of the mice that is already there in some of the mice. But that is never enough. We also need to test what would the effects be on, for example, the predators such as the harrier hawks, because we know that predators are often keystones in the ecosystem, you need to ensure that it's not doing anything to them. Now, as far as we can tell, it shouldn't do anything to them because it's just one more antibody in the soup of antibodies in each of these animals. But this is also why the mice would not be introduced on Nantucket in a trial.”