Up@dawn 2.0

Thursday, January 12, 2017

Rewriting the Code of Life

Through DNA editing, researchers hope to alter the genetic destiny of species and eliminate diseases.


Early on an unusually blustery day in June, Kevin Esvelt climbed aboard a ferry at Hyannis*, bound for Nantucket Island. Esvelt, an assistant professor of biological engineering at the Massachusetts Institute of Technology, was on his way to present to local health officials a plan for ridding the island of one of its most persistent problems: Lyme disease. He had been up for much of the night working on his slides, and the fatigue showed. He had misaligned the buttons on his gray pin-striped shirt, and the rings around his deep-blue eyes made him look like a sandy-haired raccoon.

Esvelt, who is thirty-four, directs the “sculpting evolution” group at M.I.T., where he and his colleagues are attempting to design molecular tools capable of fundamentally altering the natural world. If the residents of Nantucket agree, Esvelt intends to use those tools to rewrite the DNA of white-footed mice to make them immune to the bacteria that cause Lyme and other tick-borne diseases. He and his team would breed the mice in the laboratory and then, as an initial experiment, release them on an uninhabited island. If the number of infected ticks begins to plummet, he would seek permission to repeat the process on Nantucket and on nearby Martha’s Vineyard.

More than a quarter of Nantucket’s residents have been infected with Lyme, which has become one of the most rapidly spreading diseases in the United States. The illness is often accompanied by a red bull’s-eye rash, along with fever and chills. When the disease is caught early enough, it can be cured in most cases with a single course of antibiotics. For many people, though, pain and neurological symptoms can persist for years. In communities throughout the Northeast, the fear of ticks has changed the nature of summer itself—few parents these days would permit a child to run barefoot through the grass or wander blithely into the woods.

“What if we could wave our hands and make this problem go away?” Esvelt asked the two dozen officials and members of the public who had assembled at the island’s police station for his presentation. He explained that white-footed mice are the principal reservoir of Lyme disease, which they pass, through ticks, to humans. “This is an ecological problem,” Esvelt said. “And we want to enact an ecological solution so that we break the transmission cycle that keeps ticks in the environment infected with these pathogens.”

There is currently no approved Lyme vaccine for humans, but there is one for dogs, which also works on mice. Esvelt and his team would begin by vaccinating their mice and sequencing the DNA of the most protective antibodies. They would then implant the genes required to make those antibodies into the cells of mouse eggs. Those mice would be born immune to Lyme. Ultimately, if enough of them are released to mate with wild mice, the entire population would become resistant. Just as critically, the antibodies in the mice would kill the Lyme bacterium in any ticks that bite them. Without infected ticks, there would be no infected people. “Take out the mice,” Esvelt told me, “and the entire transmission cycle collapses.”

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