Mosquitoes kill more people each year than any other animal. In 2023, the blood-sucking insects infected a reported 263 million people with malaria, leading to nearly 600,000 deaths, 80% of which were children.
Recent efforts to block the transmission of malaria have been stalled because mosquitoes have adapted resistance to insecticides and the parasites within mosquitoes that cause malaria have become resistant to drugs. These setbacks have been amplified by the COVID-19 pandemic, which impeded ongoing anti-malarial efforts.
Now, researchers at the University of California San Diego, Johns Hopkins University, UC Berkeley and the University of São Paulo have developed a new method that genetically blocks mosquitoes from transmitting malaria.
Biologists Zhiqian Li and Ethan Bier from UC San Diego, and Yuemei Dong and George Dimopoulos from Johns Hopkins University, created a CRISPR-based gene-editing system that changes a single molecule within mosquitoes, a minuscule but effective change that stops the malaria-parasite transmission process. Genetically altered mosquitoes are still able to bite those with malaria and acquire parasites from their blood, but the parasites can no longer be spread to other people. The new system is designed to genetically spread the malaria resistance trait until entire populations of the insects no longer transfer the disease-causing parasites.
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The system targets a gene that produces a protein known as “FREP1” that helps mosquitoes develop and feed on blood when they bite. The new system switches an amino acid in FREP1 known as L224 with a genetic alternate, or allele, called Q224. Disease-causing parasites use L224 to swim to the insect’s salivary glands, where they are positioned to infect a person or animal.
Dimopoulos, a professor in the Department of Molecular Microbiology and Immunology and the Johns Hopkins Malaria Research Institute (Bloomberg School of Public Health), and his lab tested strains of Anopheles stephensi mosquitoes, the main vector of malaria transmission in Asia. They found that the L224-to-Q224 switch could effectively block two different types of malarial parasites from reaching the salivary glands, thereby preventing infection.
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In a range of follow-on tests, the researchers found that although the genetic switch disrupted the parasite’s infection capabilities, the mosquitoes’ normal growth and reproduction remained unchanged. Mosquitoes carrying the newly inserted variant Q224 exhibited similar fitness to those with the original L224 amino acid, a key achievement since the FREP1 protein plays an important role in the biology of the mosquito, which is separate from its role in being exploited by malarial parasites.
Similar to a gene-drive, the researchers created a technique for mosquito offspring to genetically inherit the Q224 allele and spread it throughout their populations, halting the transmission of malaria parasites.
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Source: CRISPR Gene Editing in Mosquitoes Halts Malaria Spread | Technology Networks
As far as I am concerned, just kill them all please: We finally may be able to rid the world of mosquitoes. But should we? (hell yes! And ticks please!)
Robin Edgar
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