Breaking the Lyme Disease Cycle

Immature ticks often acquire the pathogen after biting infected mice. ( U.S. Centers for Disease Control and Prevention )

Mice actually play a key role in the transmission cycle for Lyme disease, and researchers at MIT and Harvard are exploring genomic editing as a tool for disrupting that cycle.

Ticks, of course, serve as vectors for Borrelia burgdorferi, the bacteria that causes Lyme disease in humans. We tend to think of deer as the primary carriers, but immature ticks often acquire the pathogen after biting infected mice. The ticks then spread the bacteria to larger animals or directly to humans. Lyme disease affects up to 300,000 people per year, with New England experiencing some of the highest prevalence of Lyme and its tick vectors.

Kevin Esvelt, an evolutionary and ecological engineer at the Massachusetts Institute of Technology (MIT) and Duane Wesemann, an immunologist at Harvard's Brigham and Women's Hospital, are testing a novel approach for reducing transmission of the bacteria, beginning with mice as the original source. By analyzing the genome of white-footed mice, a key carrier of Borrelia burgdorferi on Nantucket and Martha’s Vineyard islands off the coast of Massachusetts, the scientists hope to use genomic editing to create a line of mice with genetic, and heritable, resistance to the bacteria.

Once able to propagate Lyme-resistant mice, the team proposes to release large numbers into those island habitats. After a few generations, genetic resistance would dominate the local mouse populations, and thus, fewer ticks could become disease vectors.

The team hopes to initially test their theory by releasing resistant mice onto an uninhabited private island. Once proven safe and effective, the researchers would plan to conduct large releases on Nantucket and Martha’s Vineyard. That step however, will require navigating regulatory and public-perception barriers. While some residents likely would support a program with potential to reduce or eliminate Lyme disease, others, fearing unforeseen consequences, will oppose the concept of releasing genetically altered animals into the environment. Read more.