There has never been a more powerful biological tool

Friday, January 20th, 2017

White-footed mice are the principal reservoir of Lyme disease, which they pass, through ticks, to humans — which presents an ecological solution:

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.”

[...]

Esvelt and his colleagues were the first to describe, in 2014, how the revolutionary gene-editing tool CRISPR could combine with a natural phenomenon known as a gene drive to alter the genetic destiny of a species. Gene drives work by overriding the traditional rules of Mendelian inheritance. Normally, the progeny of any sexually reproductive organism receives half its genome from each parent. But since the nineteen-forties biologists have been aware that some genetic elements are “selfish”: evolution has bestowed on them a better than fifty-per-cent chance of being inherited. That peculiarity makes it possible for certain characteristics to spread with unusual speed.

Until CRISPR came along, biologists lacked the tools to force specific genetic changes across an entire population. But the system, which is essentially a molecular scalpel, makes it possible to alter or delete any sequence in a genome of billions of nucleotides. By placing it in an organism’s DNA, scientists can insure that the new gene will copy itself in every successive generation. A mutation that blocked the parasite responsible for malaria, for instance, could be engineered into a mosquito and passed down every time the mosquito reproduced. Each future generation would have more offspring with the trait until, at some point, the entire species would have it.

There has never been a more powerful biological tool, or one with more potential to both improve the world and endanger it.

Really, what’s the worst that could happen?

Leave a Reply