Self-deleting genes to be tested as part of mosquito population control concept

Dec. 28 (UPI) -- Scientists at Texas A&M have developed a new technique for altering the genes of mosquitoes -- the new technology will cause genetic changes to self-delete from the mosquitoes' genome.

Thanks to the breakthrough, described Monday in the Philosophical Transactions of the Royal Society B, researchers can now test-run experimental gene edits without permanently altering a mosquito's genome.

"People are wary of transgenes spreading in the environment in an uncontrolled manner. We feel that ours is a strategy to potentially prevent that from happening," Zach Adelman, professor of entomology at the Texas A&M College of Agriculture, said in a news release. "The idea is, can we program a transgene to remove itself? Then, the gene won't persist in the environment."

"What it really comes down to is, how do you test a gene drive in a real-world scenario?" Adelman said. "What if a problem emerges? We think ours is one possible way to be able to do risk assessment and field testing."

Most genetic engineering strategies designed to curb mosquito populations -- and their ability to spread diseases like malaria -- call for gene edits to be combined with a gene drive. A gene drive causes the altered DNA to spread quickly throughout a population.

"A number of high-profile publications have talked about using a gene drive to control mosquitoes, either to change them so they can't transmit malaria parasites anymore, or to kill off all the females so the population dies out," Adelman said.

In the new paper, Adelman and his research partners detail a new strategy for testing gene drive systems that expire after a certain amount of time or certain number of mosquito generations.

The novel method utilizes a cellular process that all animals rely on to repair damaged DNA.

In every cell nuclei, repair enzymes constantly hunt for repeated genetic sequences that bookend broken genetic code. The enzymes delete everything in between the repeated sequences.

To take advantage of this process, researchers plan to introduce a gene drive, a DNA-cutting enzyme and a small DNA repeat to fruit flies and mosquitoes in the lab.

Once the DNA-cutting enzyme is introduced, the insect's own repair enzyme should chase down the tear and remove the gene drive and small DNA repeat from the insect's genome.

Adelman and his research partners are slated to receive $3.9 million in funding from the National Institute of Allergy and Infectious Diseases to test and improve their self-deleting gene technology.

The research team has already started testing different gene drive systems to determine how quickly they move through a population before the DNA-cutting enzyme can stop their spread.

"We assigned various rates of failure for how often the mechanism does not work as expected," Adelman said. "The models predict that even with a very high rate of failure, if it succeeds just 5 percent of the time, that's still enough to get rid of the transgene."