FDA Sheds Light on GMO Mosquito Controversy

A British company, Oxitec Ltd., has engineered a genetically modified male Aedes aegypti mosquito (the vector which transmits Zika, Dengue, and Chikungunya) (OX513A), with the target of eliminating vector populations in the release site by passing off a modified gene during mating that causes the premature death of offspring. If approved by the FDA, the mosquito would be released in Key Haven, Florida.

However, many locals are in opposition of the field trial. One Floridian, Mila de Mier, started a petition on Change.org in which she expressed her concerns, citing previous effects of GMO crop trials, and asking questions such as: “Why would we not expect GM (genetically modified) insects, especially those that bite humans, to have similar unintended negative consequences?” and “Will the more virulent Asian tiger mosquito that also carries Dengue fill the void left by reductions in A. aegypti? Will the Dengue virus mutate (think antibiotic resistant MRSA) and become even more dangerous?”

Contagion™ recently spoke with US Food and Drug Administration (FDA) spokesperson, Siobhan DeLancey, who addressed some of the concerns regarding the release of OX513A:

What is the FDA’s current stance on the matter? Will it terminate the project in response to the petition?

The FDA has posted a draft Environmental Assessment (EA) and preliminary Finding of No Significant Impact (FONSI) for public comment. Comments are submitted to a public docket that is open until May 13. The FDA will thoroughly review all public comments and information submitted to the docket on these two documents before determining its next steps. Internet petitions and public votes that are outside of the FDA docket and that are not relevant to the draft EA and preliminary FONSI are not part of this process. Oxitec will not conduct the field trial of its OX513A mosquito until the FDA has had the opportunity to review public comments on the draft EA, and subsequently has issued either a final EA and FONSI or an environmental impact statement.

How will the success of the project be determined, since there are other mosquito vectors that also transmit Zika virus?

The purpose of the proposed field trial is to assess the ability of the Oxitec mosquito to suppress the population of Ae. aegypti mosquitoes at the release site, not to assess epidemiological claims, e.g. transmission of the Zika virus, or any other virus.

There is concern that these GMOs mosquitoes can evolve and create stronger offspring that may harbor other dangerous diseases. How are you addressing this concern?

As part of its assessment of genetically engineered (GE) animals, the FDA evaluates several key aspects of the application prior to approval. One of these is durability: that the recombinant DNA (rDNA) construct encoding the engineered trait will continue to produce the corresponding traits and have the intended effect. Thus, ensuring that subsequent generations of this line of GE Aedes aegypti mosquito will continue to meet the claim. Please note that the release of the draft EA and preliminary FONSI is not an approval: that is a separate action.

Oxitec’s method is based on the sterile insect technique that has been used successfully in the United States and other countries to exterminate populations of screw worm (a painful and debilitating parasite of cattle) and, in conjunction with an integrated pest management program, the medfly infestations of California. These older sterile insect techniques used irradiation to render the insect offspring non-viable, while Oxitec’s approach is genetic and uses the overproduction of a synthetic protein to keep offspring from developing to adulthood.

Oxitec mosquitoes contain a recombinant DNA (rDNA) construct in their genome that encodes a synthetic protein (tTAV) that is lethal to the insect. Release of male GE mosquitoes (which do not bite people or other animals) to mate with local wild type (non-GE) females results in offspring that fail to develop to adulthood, thus suppressing the population of Aedes aegypti mosquitoes in the release area over time.

Contagion™ will continue to follow the progress made regarding the release of OX513A and will provide updates as they become available.