By Courtney Lepping, Stockton University
Oxitec, a biotechnology company, is launching a project that seeks to combat viral threats by using genetically modified (GM) male mosquitoes that contain a lethal gene and a gene with an identifier. The potential controlled release of the mosquito species Aedes aegypti in Key Haven, Monroe County, Florida seeks to eliminate the species through mating between males with a lethal gene and wild females that only mate within the same species. The species serve as vectors for the Zika virus. This project may effectively target the current threat from Zika disease.
According to Oxitec, the recombinant strain OX513A male mosquitoes contain a lethal construct that prevents survival into adulthood. The construct encodes the transcriptional regulatory protein tTAV. The construct also contains the gene DsRed2, the product of which serves as a fluorescent non-toxic identifier. Over-expression of tTAV leads to death in modified mosquitoes from the shutdown of other genes. Expression of tTAV is suppressed by exposure to tetracycline which causes mosquitoes carrying the lethal gene to fail to survive in the absence of tetracycline. Oxitec’s laboratory provides tetracycline, which inhibits tTAV and ensures survival. Once in the wild, offspring cannot access the amount of tetracycline needed to survive.
As stated in Oxitec’s draft Environmental Risk Assessment, it is unlikely for tetracycline concentrations to exist above 1ng/ml in mosquito breeding sites. In order to rescue the species, it would have to experience concentrations 746-2500 times greater than the expected maximum. Even more striking is that in the unlikely event that high concentrations of tetracycline exist in the environment, 95% of the GM offspring would die if they did not encounter similar concentrations again.
While the project does not threaten the human population or ecosystem, a petition started on Change.org implies a threat to human health and insists on a call to action. The petition incorporates vague language, such as drawing comparisons between GM mosquitoes and crops as well as an unreasonable emphasis on “this radical approach.” Male Aedes aegypti mosquitoes do not bite and are non-native. There is no evidence of gene transfer from female mosquitoes to bitten humans.
CBS News referenced a similar Oxitec trial conducted in 2012 that released millions of modified mosquitoes in the Cayman Islands that lead to suppression of 96% of the bugs. The FDA will consider public opinion before the release of genetically modified male mosquitoes in Florida. The FDA is sure to receive responses that conflict with the trial, as there is a lack of understanding as to how genetically modified mosquitoes function. The negativity surrounding the trial that caused a public backlash is most likely due to misinformation and fear. If Oxitec’s research methods and the science behind genetically modified organisms were clarified, public opinion might shift in favor of potential solutions to biological threats.