Scientists have now developed several genetic editing tools that help pave the way to an eventual gene drive designed to stop Culex mosquitoes from spreading disease.
As detailed in the journal Nature Communications, Xuechun Feng, Valentino Gantz and their colleagues at Harvard Medical School and National Emerging Infectious Diseases Laboratories developed a Cas9/guide-RNA expression "toolkit" designed for Culex mosquitoes. Since such little attention in genetic engineering has been devoted to Culex mosquitoes, the researchers were required to develop their toolkit from scratch, starting with a careful examination of the Culex genome.
While Culex mosquitoes are less problematic in the United States, they are much more of a health risk in Africa and Asia, where they transmit the worm causing filariasis, a disease that can lead to a chronic debilitating condition known as elephantiasis.
The researchers also demonstrated that their tools could work in other insects.
"These modified gRNAs can increase gene drive performance in the fruit fly and could potentially offer better alternatives for future gene drive and gene-editing products in other species," said Gantz.
Gantz and his colleagues have now tested their new tools to ensure proper genetic expression of the CRISPR components and are now poised to apply them to a gene drive in Culex mosquitoes. Such a gene drive construct could be used to halt pathogen transmission by Culex mosquitoes, or alternatively employed to suppress the mosquito population to prevent biting.
Photo: Larvae of the vasa-Cas9 Culex quinquefasciatus mosquito line, which was generated as part of a new genetic toolkit designed to help stop mosquito disease transmission. The image shows the glowing fluorescent protein used to track transgenic elements. Credit: Gantz Lab, UC San Diego