March 22, 2013
Mosquito Eye Color Genetically Altered To Combat Disease Transmission
Lawrence LeBlond for redOrbit.com - Your Universe Online
Two Virginia Tech researchers successfully altered the eye color of a mosquito in an ongoing effort to develop genetic strategies with the specific goal to disrupt the transmission of disease such as malaria and dengue fever.
Zach Adelman and Kevin Myles, associate professors of entomology in the College of Agriculture and Life Sciences (CALS) have been studying vector-borne disease transmission on a genetic level to develop novel methods of control.
In previous work, the two researchers used a pair of engineered proteins to cut DNA in a site-specific manner to disrupt a targeted gene in the mosquito genome. The proteins, known as transcription activator-like effector nuclease proteins (TALENS), and the way they were used was heralded by Science magazine as a major scientific breakthrough in 2012. Dubbing them “genomic cruise missiles,” the proteins allowed Adelman and Myles to target specific regions in the genome with great efficiency.
Adelman said that their research was not the first to use these TALENS, as they have been implemented in other genomic research of animal and human cell cultures. However, he did note that this is the first time the technique has been applied to a small insect, such as the mosquito.
"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 in a statement. "With the development of this technology, our understanding of the genetic basis of many critical behaviors such as blood-feeding, host-seeking and pathogen transmission should be greatly accelerated."
To test the capability of the TALENS in the mosquito genome, Adelman and Myles had to design a special pair of TALENS that would target a gene whose protein product is essential to the production of eye pigmentation in Aedes aegypti. Using the special TALENS, the duo edited the gene in the mosquito´s germ cells early in development. By doing so, they were able to change the eye color (from black to white) in a large percentage of the mosquitoes in subsequent generations.
"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."
George Dimopoulos, a professor of molecular microbiology and immunology at Johns Hopkins University said the Aedes mosquito genus has “become increasingly important as vectors of disease from a public health perspective.”
"The lack of vaccines and drugs for [dengue fever] has left the mosquitoes that carry the virus as one of the most promising targets for controlling the disease. A better understanding of how the virus infects the mosquito and other biological properties of the insect will be required to develop intervention strategies that can block virus transmission by the mosquito,” he added.
“The ability to genetically engineer mosquitoes is essential for the study of such biological functions. The TALEN-based system in mosquitoes that that was developed by Dr. Adelman provides this important capacity,” said Dimopoulos, who was not involved in the study.