Gene Drive Basics

Conserving BioDiversity

by Controlling Invasive Species
2020/by Academic Web Pages

Gene Drives: Mechanisms and Key Research, Explained

A technical primer on CRISPR-based gene drives, which hold massive potential for mitigating the harms invoked by some species. We cover what a gene drive is, how it works at the genetic level, and summarize key safety & efficiency features developed in recent years.

CRISPR could eradicate horrific parasite that’s killing cattle

Uruguay is developing a CRISPR gene drive to eradicate the New World screwworm, a parasitic fly that kills cattle in a painful, grisly fashion. Releasing it into the wild would have risks, but if it works, it could help rid South America of this horrific agricultural pest. The screwworm fly lays its eggs on living creatures — often livestock — and once they hatch, the larvae eat into the animal’s flesh for about a week, before emerging from the tunnel they created and flying away.

“We know that it’s horrendously painful, because people get affected by this, and the standard of treatment is you give them morphine immediately so that surgeons can cut the things out — because it’s just that painful; it’s unbelievably agonizing,” Kevin Esvelt, a biologist at the MIT Media Lab, told the 80,000 Hours podcast in 2023. Aside from being painful, screwworm infestations of livestock are incredibly costly. In the 1950s, the US meat and dairy industries were losing an estimated $200 million per year to the pests — that’d be about $2.3 billion today. Screwworms are no longer a problem for American farmers thanks to the USDA. In 1955, it set out to eradicate the screwworm in the US by irradiating the insects’ larvae, which made adults sterile. Infertile males could then be released into infested areas to mate with females, which wouldn’t produce any offspring.

What are gene drives, and how can they help eradicate invasive species in Australia?

The impact of feral cats and other invasive species is felt across Australia. Not only do they threaten native species, but they can also spread diseases to humans and livestock. Invasive species are estimated to cost Australia an eye-watering $25 billion annually, while the global cost is a staggering $423 billion. Feral cats are everywhere — the nation is home to up to 6.3 million of them, and they are responsible for killing millions of native mammals, reptiles, and birds each day.

Minister for the Environment and Water Tanya Plibersek recently declared "war on feral cats", announcing plans involving cat curfews, desexing regulations, and caps on cat numbers in homes. But what can we do about the millions of feral cats already wreaking havoc across Australia? And what about other pests such as foxes, rabbits, cane toads, carp, pigs, deer, or goats? One technique with the potential to help fight not just cats but all invasive species is called a "gene drive".

Improving Public Health

by Eliminating Malaria and Dengue Fever
2020/by David Obrochta

What is Genetic Biocontrol?

An overview placing gene drive technologies in a broader context
2020/by David Obrochta

Uruguay wants to use gene drives to eradicate devastating screwworms

On a warm, sunny day in Montevideo, Uruguay, the air is smogless and crisp. Inside a highly secured facility at the National Institute of Agricultural Research (INIA) are a sophisticated gene gun, giant microscopes, and tens of thousands of gene-edited flies, their bright blue wings fluttering against the walls of their small, white, netted cages.

These flies—shown to me on video by an INIA veterinarian, Alejo Menchaca—are a new weapon that may soon be unleashed against an enemy that kills cattle and costs the livestock industry millions of dollars every year: the New World screwworm, a parasite common in parts of South America and the Caribbean.

When a female screwworm fly attacks cattle, it lays eggs, which hatch and turn into worm-like larvae that screw down into the host animal, feeding on flesh along their way and damaging the animal’s skin. Left untreated, the animals eventually die in excruciating agony.

But Menchaca and colleagues have a plan. Using the genome-editing system CRISPR, they’ve developed what’s known as a gene drive, a type of genetic element that manipulates the reproductive process to spread farther and faster than an ordinary gene. They are about to move into the next stage of caged trials in the lab, with a view to eventually using the genetic tool to decimate the screwworm fly population. In collaboration with Institut Pasteur de Montevideo, they have received a $450,000 grant from the Inter-American Development Bank (IDB) for the research.

Infographic

This infographic published by the Entomological Society of America illustrates the mechanics of Gene Drive.
2020/by Academic Web Pages

Invasive Feral Cats Could Be Wiped Out Using Genetic Modification

Hordes of feral cats terrorizing native species in Australia could be combatted using a special type of genetic engineering, scientists have suggested. The cats, which came to Australia via European colonizers, regularly kill native mammals, birds, and reptiles, including woylies, quolls, and even penguins. The feral cats now number over six million, and are responsible for the extinction of at least 28 species across the country, threatening countless more. This has spurred numerous control measures to be announced, including poison, trapping, and cat curfews.

"Gene drives literally 'drive' modified genes through a species by ensuring they are inherited from generation to generation, eventually resulting in the whole species having engineered genetic traits," Andrew D. Maynard, a professor of Advanced Technology Transitions at Arizona State University, told Newsweek. "It's a technique that is specific to species that mate and reproduce sexually, and works by ensuring that engineered genetic traits are inherited by every single offspring resulting from mating."

Gene Drive: Engineered viruses take on their own kind in a new study

Scientists are exploring a radical idea to combat viral infections: use viruses against themselves. They are testing whether introducing modified viruses into people with the same natural viruses can spread a gene that destroys the infection. This has yet to be done successfully in animals, but a study has shown it is possible in theory. The technique uses gene drives, tools that use CRISPR, a gene editing system, to speed up gene transmission in the offspring. 

Gene drives have been used to alter animals like mice and mosquitoes to reduce their numbers. But a recent study showed that gene drives can also work with herpesvirus-1 (HSV-1), which causes cold sores. When mice were infected with both normal and modified herpesviruses, the gene drive changed up to 90% of the viruses, which could prevent the infection from causing symptoms. Another study achieved similar results with HSV-1 in cells in the lab.

Ethics

Two articles on the ethical dimensions of researching and using gene drive technologies
2020/by Academic Web Pages

Briefs

Two documents about gene drive technologies and their potential applications from two prestigious scientific societies.
2020/by Academic Web Pages

Mosquito makeover: Tahiti’s groundbreaking solution to disease

Mosquitoes are responsible for transmitting such diseases as dengue, malaria, zika, chikungunya, or filariosis, causing millions of deaths worldwide. French Polynesia is taking a groundbreaking initiative to address public health concerns and demonstrate a commitment to finding environmentally friendly solutions to curb disease spread. Building on a successful decade-long pilot project on the atoll Teti’aroa, the innovative method involves the strategic release of sterilised male Aedes Aegypti mosquitoes. The process sees the release of sterile males that will "contaminate" females, rendering them sterile and thereby naturally reducing the proliferation of the disease-bearing insect population. The Louis Malardé Institute's entomology laboratory says they have now developed an X-ray device that can mass-sterilise the males.

Defined

A short explanation with a basic instructional video illustrating the genetics involved.
2020/by Academic Web Pages

Increasing Food Security

by Reducing Crop Loss by Insects
2020/by Academic Web Pages

Video

Five videos on gene drive technology and biosafety, regulation, policy, governance, and ethics issues
2020/by Academic Web Pages

New Techniques of Genetic Modification in Pest Control Spark Debate in Canada

Scientists in Canada are urging serious discussions on the use of genetic modification as a new technique in pest control. In a recent report by the Pest Management Regulatory Agency, a branch of Health Canada that regulates pesticide use, experts argue that genetic modification could become a powerful tool as older insecticides lose their effectiveness and climate change leads to new infestations.

Already, such techniques are being tested to prevent mosquitoes from spreading malaria. However, the authors of the report caution that there are many unknown variables. They claim that the consequences of releasing synthetic versions of natural organisms could be harmful and permanent.

Otago GE Wasp Project Violates International Gene Drive Agreement

Professor Dearden, Otago University, has received $11 million from the Ministry of Business, Innovation and Enterprise (MBIE) to engineer wasps using gene drive technology. He is only consulting with Māori and regulators, ignoring and side-lining the views of other concerned New Zealanders.

Gene Drives using gene editing CRISPR (clustered regularly interspaced short palindromic repeat) technology. This genetic engineering causes a permanent modification of the organisms genome, which is passed on to all subsequent generations. Gene drives are designed to impact reproduction or kill the developing larvae. Due to the irreversibility of gene drives, any out-crossing across species could collapse the insect ecosystems affecting pollinators and food security.

The approval of this gene drive application is a worldwide concern, as it overrides the decision on gene drives being considered at a global level through the UN Convention of Biodiversity (CBD). MBIE and researchers at the University of Otago have violated the agreement to work in unison with the international community. International concern has already been raised by the project.

To End Malaria In Africa, a Scientist From Africa Invented Gene Drive Technology.

Abdoulaye Diabate, a scientist from Africa, is currently working on a groundbreaking technology called ‘gene drive’ that has the potential to eradicate malaria or the mosquitoes that cause it from the continent. Diabate, who received the prestigious 2023 Falling Walls Prize for Science and Innovation Management, is developing an ingenious technique that can eliminate female mosquitoes responsible for transmitting malaria by modifying their genes. Using gene drive technology, the reproduction of female mosquitoes is hindered by releasing genetically modified male mosquitoes into the environment. This approach would result in a significant reduction in the number of female mosquitoes, thereby combating malaria throughout the continent.

How do you make a gene drive mosquito?

A short video
2020/by David Obrochta

Inside Gates Foundation’s $15M effort to release gene-hacked mosquitoes that end malaria with ‘killer sex’

Malaria is a mosquito-borne disease caused by parasites and poses a significant threat to nearly half of the world's population. In 2021, an estimated 247 million people contracted malaria, with a staggering 619,000 deaths, per Imperial College. Most of those deaths affected children under five in sub-Saharan Africa.

Because current methods for fighting malaria are falling short, innovative approaches are required – enter Transmission Zero. The program's end goal is to genetically modify specific mosquito species to make them incapable of transmitting the disease. The way this works is that the gene-modified mosquitoes get sent out into the world to breed with wild mosquitoes. The result is a new generation of mosquitoes that are born with an antimalarial modification.

Types of Gene Drive

Not all gene drives are the same. Here are some examples with explanations.
2020/by David Obrochta

Genetic technologies enable the creation of transgenes that display gene drive.
2020/by Academic Web Pages

Communicating Creatively About Genetically Modified Mosquitoes

In 2018, the Target Malaria team at Imperial College London published a  landmark paper  in Nature Biotechnology. The study demonstrated how gene drive mosquitoes successfully suppressed a population of wild-type malaria mosquitoes, marking a significant milestone for gene drive technology as a tool for malaria elimination. 

In our communications team working across Burkina Faso, Ghana, Uganda and the UK, we are exploring different, creative ways to explain the technology and its progress to the general public. By continually expanding our toolkit of science communications tools and embracing innovative approaches, we hope to bridge the gap between scientific advancements and the general public, in particular communities most affected by malaria, fostering understanding and support for our mission to combat malaria.