Updated: Mar 9, 2019
Gene drive mosquitoes could end malaria, but many believe they are the making of a modern day Jurassic Park.
Recent news about experiments with gene drive mosquitoes in high security labs in Terni, Italy are causing concerns. Scientists have begun experimental gene drive mosquitoes releases within highly controlled labs. With multiple security layers, researchers can now study gene drive mosquito interactions without worrying about them escaping. As we move one step closer to releasing them into the wild, there are concerns that scientists are playing God and can destroy natural balance by creating their own version of Frankenstein’s monster. The potential unforeseeable short-term and long-term effects on the environment are giving rise to a debate on whether or not researchers should rush to release gene drive mosquitoes.
Currently there are efforts underway in Africa for open field trials with gene drive carrying mosquitoes. Target Malaria, a non-for-profit research organization, is working with researchers from Imperial College London to eradicate the spread of malaria through genetically modified mosquitoes in sub-Saharan Africa. With locations in Mali, Uganda, and Burkina Faso, Target Malaria receives significant financial funding from numerous investors, including the Bill and Melinda Gates Foundation.
Millions of people across the globe are affected by malaria each year. The malaria parasite, Plasmodium Falciparum, disguises itself in red blood cells multiplying until eventually destroying them. Relying on mosquitoes as a transport vessel, the disease parasite transfers from human to human. As mosquitoes feed, they draw up infected blood from the host and release remaining infectious backwash into their next host. The World Health Organization reports that approximately half a million people a year are killed by this parasite, most of which are children.
New genomic technologies have allowed scientists to develop novel approaches to eradicating this deadly infectious disease. Conventional approaches to malaria such as mosquito nets and repellents have not been sufficient to resolve the malaria epidemic. Researchers and global health organizations hope to capitalize on the promise of gene drive technology. Mosquitoes are now being designed to contain a lethal genetic mutation with the goal of eradicating the mosquito population in order to prevent the spread of malaria. Scientists are engineering gene drives into mosquito genetic data to ensure the lethal mutation spreads to their offspring. Gene drives rely on selfish genes that get passed on to all progeny. Normally, a gene has a 50% chance of inheritance, but gene drive allows for nearly 100% inheritance.
Mosquitoes carrying gene drive are engineered through CRISPR-Cas9, a molecular scissor used to splice DNA at targeted regions. In 2018, scientists at the Imperial College London used this gene-editing tool to target the doublesex gene in mosquitoes, creating an altered gene that is almost always inherited. By altering the doublesex gene, female mosquitoes develop male phenotypic features such as male-like mouths that prevent them from drawing blood. In addition, due to the underdeveloped female sex features, these genetically modified mosquitoes cannot lay eggs and are therefore sterile. Not only would gene drive mosquitoes prevent the spread of malaria, but they would also eradicate the mosquito population.
Proponents of gene drive research argue it is ethically and morally wrong not to take advantage of the technology's potential to save millions of lives. With this genomic technology being a stepping-stone to eradicating other diseases carried by mosquitoes, such as Zika virus, it is nearly impossible to ignore this breakthrough.
Critics, on the other hand, are claiming that by releasing gene drive mosquitoes we will face dangerous biological ramifications. They emphasize that mosquitoes are important pollinators and diminishing their population will threaten habitats. Additionally, mosquitoes hold a valuable position in the food chain, providing nutrition to several animals such as birds and bats. By removing them from this food chain we can expect to see negative effects on animal populations.
Others, however, insist that ecology has the ability to adapt. Darwinians believe that the environment will undergo adaptations in order to survive. By eradicating mosquitoes, it is likely that the pollinating role of mosquitoes will be replaced by other insect species. Additionally, some critics also claim that mosquitoes have no pollinator traits. In terms of food chains, there is no evidence to suggest that any animal species heavily depends on mosquitoes in their diet.
There is also an ongoing debate on the efficacy of this approach. If gene drive carrying mosquitoes were to be released, would they eradicate malaria or open the door to a deadlier disease? Critics fear that mosquitoes will be replaced by an insect that is equally or more undesirable, as it may adapt in a way that allows disease to spread at faster rates than it did before. The idea of these mosquitoes crossing with other species to create something entirely new is also alarming. In an age of global travel, there is a possibility that gene drive mosquitos may spread around the world. With their new genetic data, it is unforeseeable what it might give rise to.
Neither side of the debate has presented compelling evidence of what the exact effects of releasing gene drive mosquitos into the wild will be. Since this is a novel research area, currently there is no sufficient data to evaluate the risks and create reliable risk models. Given the uncertainty involved in gene drive research, Target Malaria must focus on gathering sufficient information to determine ecological risks such as what coexists with mosquitos and what might fill the gap following their eradication. A thorough assessment of possible impacts on human health is also required. Prior to the release of gene drive mosquitos, we need more transparency about how risks are evaluated and should engage the public in all steps of the process. Only then will both researchers and global health organizations be able to make informed decisions.