Nantucket Battle Against Lyme Disease: The Role of Engineered Mice
In the small island of Nantucket, just off the coast of Massachusetts, a single physician has been tirelessly battling a health crisis. This lone doctor has been treating numerous Lyme disease cases annually. Remarkably, about 15% of the island's inhabitants have suffered from this disease, which can lead to symptoms such as fever, rash, facial paralysis, irregular heartbeats, and arthritis.
But it seems there might finally be a breakthrough in the fight against Lyme disease. A group of scientists is aiming to reduce the disease's transmission by focusing not on the deer or ticks usually linked with the illness, but on wild mice, the primary carriers of Lyme bacteria. The scientists propose to genetically modify these mice to be immune to Lyme and then release them on the island. Their theory is this will reduce the number of mice transmitting Lyme disease.
Why Nantucket Is the Focus
The problem on Nantucket dates back to the 1920s, when two female deer were introduced to the island to keep a lone male deer company. Furthermore, by the 1950s, half of the island's land was conserved. This preservation led to an explosion of wild grasslands and brush, providing the perfect habitat for Lyme disease hosts.
With the increase in the deer population, the number of ticks also escalated. While deer don't contract Lyme, female ticks feed on them, laying up to 2,000 eggs at a time. Deer further spread the disease by carrying ticks across the island.
However, not all ticks carry Lyme disease, and a tick bite doesn't automatically lead to transmission. Even if the tick is carrying Lyme, it must be attached for more than 24 hours to transmit the disease. It's important to note that white-footed mice are the primary hosts of Lyme bacteria. The cycle continues when an infected tick bites an uninfected mouse.
Despite the ability to treat Lyme disease with antibiotics, if left untreated, it can spread to the heart, joints, and nervous system. Around half a million people per year are affected by Lyme disease in the United States, although it's rarely fatal.
The Scientists' Vision
In 2013, a groundbreaking discovery was made that CRISPR technology could permanently change a species' genetics. This led to the Mice Against Ticks project. The past nine years have been spent exploring whether they could introduce a gene for an antibody that prevents Lyme disease into a mouse embryo.
The scientists' technique involves injecting both cells of a two-cell embryo to maximize the chances of incorporating the antibody into the DNA. The injection mix contains both the antibody gene and CRISPR, which acts like molecular scissors. After CRISPR finds and cuts the targeted DNA area, the cell inserts the antibody gene into the mouse's genetic code.
Once the mouse is born, it will be immune to Lyme disease, and so will its offspring. The immunization is heritable.
The plan is to release thousands of these engineered mice on Nantucket over time. As the immune population grows, the spread of Lyme disease on the island should decrease.
Anticipating the Consequences
Such a plan would, in essence, speed up evolution, a process that usually occurs very slowly, over thousands or even millions of years. This is why the scientists advocate caution and community approval before proceeding.
Local residents have expressed concerns about potential impacts on the natural environment. The scientists have presented their findings to the community through a series of town halls, followed by public Q&A sessions. While some residents see the potential benefits, others worry about the implications of tampering with the food chain.
The physician, an enthusiastic supporter of the proposal, has some reservations. As a keen falconer, he is concerned about potential unintended consequences on the island's ecosystem and advocates for more testing.
If they get the green light from federal and state regulators, the scientists plan to first release the engineered mice in a small field trial on a private island. This will allow them to better understand the ecological impacts before any potential experiments on Nantucket.