Several researchers are seeking mosquito genetic modification techniques in order to monitor mosquito species and deter them from spreading diseases such as malaria. A recent Texas A&M AgriLife Research project intends to make temporary "test runs" of potential mosquito genetic modifications, during which the changes are deleted from the genetic code of the mosquitoes.
In laboratory studies, effective genetic solutions have been established but can never be used in use until they can be proven to be appropriate by comprehensive field-based research. The predicted challenge of eliminating "gene drive transgenes" from nature complicates such research. The research considered the incorporation of pathways of self-elimination in the design of transgenes driving homing-based genes in mosquitoes.
The models in the study indicate that this process, operating at a moderate pace (10 percent) as part of a single-component device, will be adequate without the need for further remediation to trigger the rapid reversion of even the most stable 'homing-based gene drive transgenes.'
“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,” Adelman said as quoted in AgriLife Today. “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?” he added. “What if a problem emerges? We think ours is one possible way to be able to do risk assessment and field testing.”
According to experts, there are three methods to eliminate an incorporated genetic alteration during its defined length of time. The time span may be 20 generations of mosquitoes, for example, or around a year. To simulate how genes can propagate, the team made a simulation with data from an ordinary mosquito's existence. Of the three approaches, the team selected one to explore further.
This approach takes advantage of a mechanism used by all animals to restore degraded DNA, said Adelman. Reparation enzymes scan within cell nuclei for replicated genetic sequences along damaged DNA strands. Then, he said, the repair enzymes erase what is between the repeats.
So, Adelman and Myles' team is preparing to evaluate a gene pump, a DNA-cutting enzyme and a tiny repeat of the insect's own DNA in fruit flies and mosquitoes.
Once the enzyme cuts the DNA, the insect's own repair machinery could hop in to counterattack. For the gene drive and the other inserted sequences, the repair instruments would hack out the genes. That's what, at least, could happen in principle.