Genetic Strategies for Controlling Mosquito-Borne Diseases
Engineered genes that block the transmission of malaria and dengue can hitch a ride on selfish DNA and spread into wild populations
Malaria infects hundreds of millions of people each year and kills a million of them, mostly small children. It has no vaccine, and treatments are losing efficacy as the parasite evolves to resist their effect. Malaria, like several other tropical diseases including dengue fever, are spread through the bite of an infected mosquito, and public health initiatives to combat these diseases have focused on insecticides and netting with limited success. But what if mosquitoes could no longer transmit the disease? In the laboratory, scientists have succeeded in adding specific genes to the mosquito that make it unable to transmit the parasites that cause malaria or dengue. It might be possible to cause similar changes to wild mosquitoes. The tricky part would be getting the disease-blocking genes to spread to the whole population: Thousands of transgenic insects would have to breed with and eventually replace the local mosquitoes. Furthermore, adding genes to an organism generally hampers its ability to thrive, so natural selection would seem to work against the modified insects. Nonetheless, recent experiments suggest that genetically altered mosquitoes could provide a realistic solution to the problem of mosquito-borne diseases-provided that some of the large technical hurdles can be overcome. Gould, Magori and Huang describe some of the sophisticated genetic strategies that could be used to drive anti-parasite genes into a population of wild mosquitoes as well as the risks attendant in such a scheme.
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