Laboratory experiments on fruit flies have shown that a modified gene introduced into one individual fly can take just a few generations to “infect” practically every other fly in the breeding population, in defiance of the normal rules of genetics which dictate a far slower spread.
Kevin Esfeldt, a gene-drive expert at the Wyss Institute at Harvard Medical School in Boston, said the technology was developed theoretically about 10 years ago but it has only been made possible in the lab in the past two years with the discovery of the sophisticated gene-editing tool Crispr/Cas9.
Dr Esfeldt explained that gene drives relied on a “cassette” of genetic elements that allowed a genetically modified gene to jump from one chromosome to another within the same individual so that eventually all of the sperm or eggs of the animal carried the GM trait, rather than half. This means that virtually none of the offspring is eventually free of an introduced GM trait.
Gene drives could benefit human health by altering insect populations that spread human diseases, such as mosquitoes that transmit malaria, dengue, chikungunya and Lyme disease, so that they were no longer a threat, he said.
Debate still rages over genetically modified food after nearly 20 years (Getty)
They could also be used to reverse the mutations that make crop pests resistant to agricultural pesticides, or they might be used to spread genetic traits within a populations of an invasive species to help kill it off, such as making the skin of cane toads introduced into Australia non-toxic to indigenous predators.
“If we’re right about this, it’s a powerful advance that could make the world a much better place, but only if we use it wisely,” Dr Esfeldt said.
However, some scientists fear that the ease with which gene drives can be generated will make them a target for any malign individual or organisation with access to modern laboratory equipment.
Dr Gurwitz said the precise instructions for making gene drives should be classified, just like the technology for making nuclear weapons. However, Dr Esfeldt and the other 26 scientists who have written to Science disagreed, arguing that complete openness and transparency was the best defence against the use of gene drives as a bio-weapon because classifying the information would be technically ineffective and politically counterproductive.