Malaria has afflicted humans for millennia. Even today, the mosquito-borne, parasitic disease claims more than a half-million lives annually . Now, in a study that has raised both hope and concern, researchers have taken aim at this ancient scourge by using one of modern science’s most powerful new technologies—the CRISPR/cas9 gene-editing tool—to turn mosquitoes from dangerous malaria vectors into allies against infection .
The secret behind this new strategy is the “gene drive,” which involves engineering an organism’s genome in a way that intentionally spreads, or drives, a trait through its population much faster than is possible by normal Mendelian inheritance. The concept of gene drive has been around since the late 1960s ; but until the recent arrival of highly precise gene editing tools like CRISPR/cas9, the approach was largely theoretical. In the new work, researchers inserted into a precise location in the mosquito chromosome, a recombinant DNA segment designed to block transmission of malaria parasites. Importantly, this segment also contained a gene drive designed to ensure the trait was inherited with extreme efficiency. And efficient it was! When the gene-drive engineered mosquitoes were mated with normal mosquitoes in the lab, they passed on the malaria-blocking trait to 99.5 percent of their offspring (as opposed to 50 percent for Mendelian inheritance).
This inheritance pattern persisted through three generations of gene-drive engineered male mosquitoes mated with normal females. With such highly efficient transmission, the researchers estimate that the malaria-blocking trait could be spread throughout an entire local population of mosquitoes in just a single breeding season by releasing one gene-drive engineered mosquito for every 100 mosquitoes in the wild.
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