Mosquito-borne malaria kills more than 600,000 people each year, mostly children under the age of five. Some disease-carrying insects, such as mosquitoes, are now expanding their range around the world, posing new threats. Genetic engineering can fix this by permanently altering an insect’s genes through what is known as a gene drive.
This technology allows a selected set of genes to alter an animal’s biology in some way. For example, it can produce infertile offspring. Infertility is rampant throughout the population, upending the laws of heredity. The genes copy themselves exponentially from generation to generation and rapidly come to dominate the entire population. , the complete elimination of insects could save millions of lives. Become.
Still, you don’t have to be a Luddite or techno-thriller writer. Ecosystems are complex, and the balance of delicate ecosystems can be greatly disrupted. Poorly engineered gene drives can even pounce on disease-free relatives, for example, causing a disastrous cascade.
Austin Burt of Imperial College London came up with the gene drive in 2003. He envisioned a system in which genes would produce DNA-cutting enzymes (endonucleases) that precisely target the chromosomal location of the gene that encodes them. Such systems are found naturally in fungi but not in animals.
When an individual that has two copies of such a gene mates with another that does not, all offspring initially have only one copy of the gene on the chromosome they inherited from the gene drive parent. However, soon after fertilization, the nuclease cleaves her DNA sequence on the other chromosome from the parent that did not carry the gene, at the exact location of the gene drive. The cell then uses the intact chromosome to reconstruct gaps in her DNA sequence on other chromosomes.
Where there was only one copy of the gene, there are now two in all offspring. The same thing happens with the next generation. The frequency of genes in the population increases exponentially.
Burt then linked one of these endonuclease genes to a gene that induces infertility or confers immunity to the mosquito against the malaria parasite, theoretically injecting the trait into the population. I have noticed that I can either kill the mosquitoes completely or keep them away from malaria. vector. Success will have a great impact on human health. The challenge, however, has been how to introduce endonuclease genes and their associated gene payloads into genomic locations where they can safely function without inadvertently affecting other aspects of animal physiology.
After the advent of CRISPR-based gene editing in 2013, this dream became a reality. And in 2015, researchers at the University of California, San Diego created a gene drive for harmless vinegar flies in the lab. Drosophila It simply turned all the flies’ eyes yellow. In other words, they created what could be considered a “genetic atomic bomb.” Once he releases even one of these things into the wild, there is no way to stop it.
Researchers around the world soon developed gene drives for mosquitoes. In laboratories, large populations of mosquitoes disappeared in less than a year, thanks to gene drives. At least in insects, no technical obstacles exist to the release of such gene bombs. Creating mammalian gene drives remains a major problem (currently non-existent). This is due to the way cells respond to DNA breaks at different points in their life. A naturally occurring genetic element that exhibits some of the behavior of a gene drive has recently been exploited in mice, but has not yet been proven to alter population-wide DNA. Due to these technical issues, it may not be possible to use this technology to wipe out invasive rodents, for example.
In response to the potential ecological threat of gene drives, the US National Academy of Sciences, Engineering, and Medicine, with support from the Defense Advanced Research Projects Agency, the primary agency funding gene drive research, A committee has been set up to study this issue (DARPA). The agency, part of the Department of Defense, has a strong interest in the potential of technology as a security threat. After weighing both the potential benefits and the great uncertainty about what might happen, the Commission’s 2016 report’s conclusions were clear. of gene-driven modification organisms to the environment. “
This statement did not allay all concerns. Kevin Esvelt, a gene drive pioneer at the Massachusetts Institute of Technology, predicted that by 2030 there will be lab leaks or other incidents linked to gene drives. “Let’s go,” he said in 2016. Regulatory safeguards and public involvement had to be built in from the beginning of considering using the technology, he argued.
The immediate question for bioethicists and regulators is whether gene drives should be released from the lab. The main international framework for gene drives is the United Nations Convention on Biological Diversity. Of all United Nations member states, only the United States has not signed the treaty and is unlikely to do so. Researchers at Stanford University, including Francis Fukuyama, are calling for the creation of a gene drive regulatory agency, in line with standards-setting bodies such as the International Civil Aviation Organization (ICAO). However, ICAO was established in 1947, at a time when countries were seeking international regulation.Regulating gene drives requires major political change worldwide, especially in the US
Concerned about potential ecological damage and suspicious of DARPA and other funders, gene-driven opponents are calling for a research moratorium. Research continues nonetheless, but there is general agreement that an environmental risk assessment and the active involvement of affected communities are required before any release is considered. Because of the potential, people should provide so-called free prior informed consent.
Active efforts are underway to test what would happen if the gene drive were released into the wild. In 2021, a researcher at Imperial College London, funded by Target Malaria (a non-profit research consortium funded by the Bill & Melinda Gates Foundation), will study his eight major ecology of gene drives. identified a positive effect. Among the potential problems they investigated was the spread of gene drives to valuable non-target species, reducing their density and the health of ecosystem services. Gene drives also carry the risk of unanticipated genetic alterations in target species. For example, they may become able to tolerate a wider range of environmental conditions, allowing disease-spreading insects to spread instead of being eliminated. Even with community support, each possibility needs to be tested in the field before decisions are made about deploying genetically modified insects.
Obtaining community consent proved to be very difficult. With the approval of the government of Burkina Faso, Target Malaria released sterilized and fluorescent powdered non-gene-driven mosquitoes in July 2019 to study how far the gene-driven mosquitoes traveled and how far the gene-driven mosquitoes traveled outside the region. We explored the potential risks that spread to Since there is no word for “gene” in the local language, researchers had to invent a term. They also used theater to illustrate their projects and ensure that illiteracy is not a barrier to understanding and decision-making.
Nevertheless, the lack of knowledge left some villagers feeling helpless. “They say they’re going to eradicate malaria, which we believe because we’re not scientists, but we still have questions about future risks,” said one farmer. world And as one woman was quoted as another woman’s words world A 2018 article, “In any case, we have no say. Men make all the decisions here.”
Giving local communities a veto is essential, but insects don’t respect national borders, so gene drives challenge our notions of what “local” is. , “If you release it anywhere, it can be released anywhere.”
People in malaria-stricken villages may want to be ready to do whatever it takes to get rid of mosquitoes and save the lives of children. It is not clear whether it should have the right to decide. So some kind of international oversight body with regulatory powers like ICAO is essential.
You may have nothing to worry about. The insects that are currently being targeted are not the only food source for other animals.However, malaria mosquitoes Anopheles gambiae It is eaten by various species. Even the slightest hunger can lead to unforeseen ecological problems as predators shift their attention to other prey to relieve hunger and destabilize the delicate ecological balance. .
The move to adopt gene drives is also tricky, as simpler, less radical solutions may be at hand. WHO has approved her vaccine for malaria in late 2021, and more than 1 million African children have received one or more doses of her in a pilot study.
The aims of gene drive researchers are precise, bounded in time and space, and commendable and humane.Nobody Plans To Give A Massive Biocide Like Marvel’s Thanos the avengers movie. Before any gene drive can be deployed, it must be subject to the strictest scrutiny and international regulation. Otherwise, the cure may prove to be worse than the disease.
This is an opinion and analysis article and the views expressed by the author or authors are not necessarily Scientific American.
