The war against malaria has a new ally: a controversial technology for the dissemination of genes in a population of animals. Researchers now report that they have used a so-called gene reader to effectively confer mosquitoes with genes that should make the parasite shed malaria and unable to spread. On its own, gene reader will not get rid of malaria, but if it is successfully applied in the nature of the method could help eradicate the disease, at least in some corners of the world.
The approach "may lead us to zero [cases]," says Nora Besansky, a geneticist at the University of Notre Dame in South Bend, Indiana, who specializes in mosquitoes carry malaria. "mosquitoes do their own work [and] reach places that we can not afford to go or to go to."
But test this promise in the field may have to wait until a broader debate on the readers gene is resolved. the essence of this long-discussed strategy for the dissemination of a genetic trait, such as disease resistance, is to bias the heritage so that more than half the expected subsequent generation inherits. gene drive concept has attracted new attention earlier this year when geneticists studying fruit flies adapted a gene editing technology called CRISPR-case.9 to help spread a mutation and were surprised to find it worked so well that the mutation has reached almost all offspring fly. Their report, published this spring Science came out less than a year after eLife paper discussed the feasibility of CRISPR-case.9 gene drive system, but warned that it could disrupt ecosystems and wipe populations of entire species.
A firestorm quickly erupted on the risks of experimenting with genes players, applying them in the field Nevermind. The US National Academy of Sciences (NAS) convened a committee to assess risks and propose protection measures, and the authors of eLife and Science documents have laid lines guidelines for experiments.
Meanwhile, over the past 20 years, Anthony James, a geneticist at the University of California (UC), Irvine, dreamed of engineering a gene unit that would spread makes DNA mosquitoes unable to host the malaria parasite. In 2012, his team stuck mouse genes for antibodies that make rodents immunized against the agent of human malaria and put them in a species of mosquito that spreads malaria in India. Antibodies, as expected, interrupted the parasite's life cycle in the insect. But James was no way to push the antibody genes in millions of mosquitoes in nature. It explores the development of a training method of genes using transposable elements, odd bits of DNA that can jump between chromosomes, but never succeeded.
Earlier this year, however, James received an email from Ethan Bier, a geneticist at UC San Diego whose lab has done research soon-to-be-released genes drive in flies fruits. Bier thought he had a solution to the dilemma of James. "As soon as we saw [gene drive] might work, we thought of mosquitoes," says Bier. James was delighted. "I looked and realized their data [they] is what I was proposing obsolete."
But he wonders if the Bier gene drive system could carry heavy 17,000 DNA bases containing the genes mouse antibody. "the question was" would it carry a large cargo will remain active? "James remembers. he and Bier teamed to see.
Valentino Gantz laboratory Bier and Nijole Jasinskiene , a molecular biologist at UC Irvine, began with male and female engineering Anopheles stephensi to execute the gene drive system. They designed the system so that, along with the dissemination of antibody genes from one half of a pair of chromosomes to the other, the polarizing key inheritance- it would also cut a piece of a gene for eye color When coupled with the modified mosquitoes normal, they could quickly see if the gene player had wrought .. offspring who also inherited the antibody genes had white eyes
technology was effective, giving about 99% of the offspring of the male transgenic with added genes, teams of Bier and James reported today in the Proceedings of the national Academy of sciences . And, as expected, these genes were active in mosquitoes. Previous experiments had shown that if the antibody genes were expressed, they thwarted the parasite. And modeling suggests that a gene reader of this effectiveness, it should only take about 10 generations of mosquitoes for malaria genes to completely infiltrate a population.
The system was not perfect. The gene reader does not work as well when started in female transgenic mosquitoes. In addition, the case.9 protein used in gene editing technology can be toxic to mosquitoes, the team had to twist where insects it was made and how to improve the survival rate of offspring. Yet the strategy is working. "It is really a big problem," says Besanksy. "It is not only a gene drive system. It is a gene drive system that carries suppressors genes." "We have all the pieces," adds James. "It is a matter of [making] a product that people want."
, which is the big event. James, Bier, and colleagues adequately addressed concerns about accidental releases GM mosquitoes, say several external researchers contacted by science . insectariums were behind five sets of doors, and they used a mosquito does not survive in California, should he manage to escape.
But before the work continues, says evolutionary engineer Kevin Esvelt Harvard University biologists should look at the ecological effects of changes induced genes, make sure that the changes are stable for many generations, and develop a way to counter or get rid of gene drive in case of problems.
Because pest control genes should continue to propagate indefinitely in a population of mosquitoes, national and international regulations must be developed before the genes drives are deployed in the field, says sociologist Kenneth Oye the Massachusetts Institute of Technology in Cambridge. The drive ratio of the NAS gene, due next year, can help in this regard. "How will we decide as a society whether, when and how to use gene reader to solve a problem?" Request Oye.
Esvelt, which is already in discussion with the public, physicians and government officials about the spread of genes of Lyme disease in anti-mouse even if the genes drives has not been shown in mammals, said a consensus must be reached. "at the end of the day, unless you have broad public support, you can not do it. "
James accepts that his dream may be deferred for now." if it is that we are too far ahead of the curve, we will just wait for people to catch, "he said. "I hope not to have to wait for the rest of my productive career, but if we can not find a way to do it ethically, it will not."
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