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For the first time, scientists have demonstrated that a new type of controversial genetic engineering can quickly spread a self-destructive genetic modification across a complex species.
Scientists used the revolutionary gene editing tool called CRISPR to make mosquitoes with a "gene drive" that quickly transmitted a sterilizing mutation to other members of the mosquito species.
After the mosquitoes carrying the mutation have been released into cages filled with mosquitoes in a high-security underground laboratory in London, virtually all insects were wiped out, according to a report by Nature Biotechnology.
The mosquitoes were created in the hope of using them as a powerful new weapon in the long frustrating fight against malaria. Malaria remains one of the deadliest in the world diseases, killing more than 400,000 people each year, mostly children under 5 years old.
"We are very excited," said Andrea Crisanti, professor of molecular parasitology at Imperial College London, who led the research. "It's changing the game, it's a completely new era in genetics."
Other researchers are in agreement.
"This is an extraordinary document," says Kevin Esvelt, evolutionary engineer at the Massachusetts Institute of Technology and a leading researcher in the field of "gene discovery". He was not involved in the new research.
"We know what the costs of malaria are – and they are horrible," says Esvelt. "It could save a lot of lives."
Crisanti, Esvelt and others are particularly encouraged because the mosquitoes did not seem to mutate in a way that would diminish the effectiveness of the manipulated mutation. This has been a major problem that has hit attempts to use the genetic drive.
"It's a really exciting job – it's a major development," says Omar Akbari, an assistant professor at the Cell Biology and Developmental Section of the University of California at San Diego.
But the researchers pointed out that many years of additional research is needed to further test the safety and effectiveness of the approach before anyone tries to release those mosquitoes or any other organisms created from this. way in nature.
Scientists recognize that technology raises serious concerns. This will require wide political debate, rigorous regulation and the consent of people living in areas where they could be released, they say.
The research sponsor, Target Malaria, has already begun extensive discussions with countries in Africa where mosquitoes may eventually be released.
Nevertheless, there is already intense opposition among some activists.
"Africa has become a testing ground for a technology that has not been proven – a technology that no-one can say without danger," says Nnimmo Bassey, director of Nigeria's Health of Mother Earth Foundation. "We have a problem with that."
A major criticism is that the eradication or the significant removal of an entire species could have unpredictable effects on the environment, according to critics.
"This could lead to ecosystem crashes," says Ricarda Steinbrecher, a biologist with the ECONEXUS group.
"It could cause other species to fill a niche that is even more problematic," says Steinbrecher. "It's beyond our ability to predict what the consequences are, except that it could be really devastating."
Some fear that the approach may be used to create new biological weapons.
"The defense industry could deploy this as a weapon of war," said Jim Thomas, co-executive director of ETC Group, an international technology monitoring agency. "You could use a search for genes in an insect that could deliver something toxic."
Crisanti rejects the idea that genetic drives could be used to easily create new biological weapons. While acknowledging the concerns, which have been reviewed by many scientific organizations, Crisanti and others argue that the potential benefits far outweigh the risks.
"I consider a mosquito that transmits malaria as a pathogen – and as a pathogen, we have the right to eliminate it," says Crisanti. "We've eliminated viruses like smallpox, we're trying to eliminate polio, I do not see a big difference."
The technology could also be used to target other disease-spreading insects, such as mosquito species that spread diseases, including Zika and dengue fever. Genetic mechanisms could also be used to control agricultural pests.
"It opens up a lot of possibilities," says Crisanti.
Gene readers are DNA sequences that defy the usual rules of genetics. They can be passed on to the future generation at a much faster pace than what happens naturally.
The existence of genetic drives has been known for years. But it is only during the development of CRISPR that scientists have been able to try to control their power. CRISPR allows scientists to make very precise modifications of DNA much more easily than ever before.
The British team used CRISPR to create a genetic drive that altered part of a gene known as "doubleex". This gene plays a crucial role in determining whether individual mosquitoes are men or women.
Male Anopheles gambiae mosquitoes with the mutation can mate with normal female mosquitoes, passing along the modified gene. Anopheles gambiae Mosquitoes are the main vector of malaria spread in sub-Saharan Africa.
Females with a copy of the mutation also behave normally and are in good health, which allows them to continue to propagate the mutation. Experience has shown that the mutation is transmitted almost 100% of the time.
But female mosquitoes born with two copies of the mutation have characteristics of both males and females, which makes them unable to bite – and thus spread malaria.
They are also unable to lay eggs. The new research shows that when the mutation spreads to enough female mosquitoes, populations of the species eventually break down because they can no longer produce offspring. This occurred after seven to eleven generations, which in the lab lasted only about six months, according to Crisanti.
The research was funded by several organizations, including the Bill & Melinda Gates Foundation, which also provides support to NPR.
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