Altering mosquito genome may help combat dengue fever

Scientists have successfully used a gene disruption technique to change the eye colour of a mosquito - a critical step toward new genetic strategies aimed at disrupting the transmission of diseases such as dengue fever.
Researchers from Virginia Tech (Virginia Polytechnic Institute and State University), used a pair of engineered proteins to cut DNA in a site-specific manner to disrupt a targeted gene in the mosquito genome.
These transcription activator-like effector nuclease proteins, known as TALENS, were heralded by Science magazine as a major scientific breakthrough in 2012, nicknaming them "genomic cruise missiles" for their ability to allow researchers to target specific locations with great efficiency.

While TALENS have been previously used to edit the genomes of animal and human cell cultures, applying them to the mosquito genome is a new approach, according to Zach Adelman, from the College of Agriculture and Life Sciences and the Fralin Life Science Institute.
"Unlike model organisms with large collections of mutant strains to draw upon, the lack of reverse genetic tools in the mosquito has made it is very difficult to assign functions to genes in a definitive manner," Adelman said.
"With the development of this technology, our understanding of the genetic basis of many critical behaviours such as blood-feeding, host-seeking and pathogen transmission should be greatly accelerated," he said in the study published in journal PLOS One.

To test the capability of TALENS to specifically edit the mosquito genome, scientists, including Kevin Myles, designed a pair of TALENS to target a gene whose protein product is essential to the production of eye pigmentation in Aedes aegypti.

The mosquito species is known for its transmission of the viruses that cause dengue fever.
Using the TALEN pair to edit the gene in the mosquito's germ cells early in development, they were able to change the eye colour of a large percentage of the mosquitoes arising in the next generation from black to white.
"To date, efforts to control dengue transmission through genetics have focused entirely on adding material to the mosquito genome. Ensuring that this added material is expressed properly and consistently has been a challenge," Adelman said.

"This technology allows us to pursue the same goals, namely, the generation of pathogen-resistant mosquitoes, through subtraction. For example, removing or altering a gene that is critical for pathogen replication," he said.