Loading...
This record has been deleted. Since it is linked to a published record, it is available here for reference purposes only.
Click here to view the deleted recordThis document has been updated. This is not the latest published version. Click here to view the latest version of the record.
Risk Assessment generated by an independent or non-regulatory process
(IRA)
last updated: 03 Dec 2025
Risk assessment of Aedes aegypti OX5034 for the control of arboviral diseases
EN
07 Feb 2025
-
- Inter-governmental organization (IGO)
Av. Cayetano Germosén, esq. Av. Gregorio LuperónSanto Domingo, Distrito Nacional
,Phone: +809 567 4300,Fax:
-
Person:Mr. Ediner FuentesSub Director, Dirección de Investigación y DesarrolloEdificio 203, Ciudad del Saber, PanamáPanamá, Panamá
, PanamaPhone:Fax:Email: efuentes@senacyt.gob.pa,Website: -
Person:Dr. Paulo Paes de AndradeDept. of Genetics, Federal University of Pernambuco Av. Moraes Rego, s/nRecife, Pernambuco
506070-901,Phone: +55 81 21 26 85 69,Fax: +55 81 21 26 85 69,Email: andrade@ufpe.br,Website:
-
2nd Generation Friendly™ Aedes aegypti| Oxitec Limited | Changes in physiology and/or production (Reproduction), Changes in quality and/or metabolite content (Pigmentation / Coloration), Female-specific lethality
The results indicate minimal impacts on human health and biodiversity. The release would focus on urban and peri-urban areas where Aedes aegypti is prevalent. While potential risks to mosquito-feeding species in these environments have been identified, it is unlikely to cause significant adverse effects on ecosystems or protected species. The adoption of this control technology is recommended, accompanied by low-intensity post-release monitoring to confirm the absence of unforeseen impacts. This would significantly contribute to national public health strategies and environmental regulations, helping to mitigate diseases such as dengue, Zika, and chikungunya.
In conclusion, the release of the OX5034 mosquito represents a low risk, and its implementation could be an effective step in controlling mosquito-borne diseases, aligning with the public health and sustainability objectives of the Dominican Republic.
In conclusion, the release of the OX5034 mosquito represents a low risk, and its implementation could be an effective step in controlling mosquito-borne diseases, aligning with the public health and sustainability objectives of the Dominican Republic.
1. The documentation submitted in the procedure provides the necessary information to assess the risks that the genetically modified mosquito OX5034 (originally OX513A) may pose to human and animal health. As indicated below, the applicant clearly defines the relevant aspects, establishing:
a) Protection goals and assessment endpoints aligned with the safety objectives defined by Dominican legislation;
b) Biology of the recipient organism;
c) Characteristics of the likely receiving environment;
d) The genetic construct or genetic control sequences (vectors, promoters, terminators, ribosomal binding sites, and other DNA sequences that control gene expression), and the expected phenotype. This includes genes inserted, deleted/silenced, or modified—originating from another organism (of another species) or from synthetic DNA sequences—and the expressed traits (synthesized or silenced proteins);
e) History of safe use, if available, in an environment similar to the receiving environment where the GMO will be confined or released.
b) Biology of the recipient organism;
c) Characteristics of the likely receiving environment;
d) The genetic construct or genetic control sequences (vectors, promoters, terminators, ribosomal binding sites, and other DNA sequences that control gene expression), and the expected phenotype. This includes genes inserted, deleted/silenced, or modified—originating from another organism (of another species) or from synthetic DNA sequences—and the expressed traits (synthesized or silenced proteins);
e) History of safe use, if available, in an environment similar to the receiving environment where the GMO will be confined or released.
2. Description of the GMO
The genetic construct in OX5034 is designed with two main elements:
a) A female-specific tTAV expression system. This system includes a minimal DmHsp70 promoter along with TetO operators that control tTAV expression, creating a positive feedback loop that functions only in females due to sex-specific alternative splicing.
b) The second key component is the DsRed2 fluorescent marker gene, an improved version of the natural fluorescent protein derived from Discosoma spp. DsRed2 expression is driven by the HR5-IE1 promoter and transcriptional enhancer from the AcNPV virus and includes nuclear localization signals to enhance visualization.
tTAV is a synthetic protein resulting from the fusion of two domains: one is the tetracycline-binding domain from tTA (derived from E. coli), and the other is the transcriptional activation domain from the herpesvirus VP16 gene. This protein is predominantly produced in female mosquitoes through the incorporation of a sex-specific splicing module that produces distinct mRNA isoforms in each sex.
DsRed2 is a fluorescent protein that enables the visual identification of transformed individuals (males and females) during larval, pupal, and adult life stages. It is derived from DsRed, a naturally fluorescent protein originally found in Discosoma spp. The HR5-IE1 promoter and enhancer from Autographa californica nuclear polyhedrosis virus (AcNPV) drive its expression.
The full construct is flanked by piggyBac 5' and 3' transposon sequences, which facilitate genomic integration, and includes several additional regulatory elements such as ubiquitin sequences for protein processing and SV40 regulatory regions.
The OX5034 line was produced by microinjecting the pOX5034 plasmid construct along with piggyBac transposase mRNA into individual Aedes aegypti embryos.
The phenotypic changes are limited to conditional lethality and fluorescence, which is only observable under ultraviolet light. No other behavioral or morphological changes are expected.
3. Evaluation under Cartagena Protocol and National Regulations
The evaluation follows the guidelines of Annex III of the Cartagena Protocol and the national regulatory framework, ensuring compliance with environmental and biosafety standards.
According to the Dossier (Book D, Section 1), the OX5034 construct implies the conditional expression of a lethal gene. The stability of the construct is demonstrated in the documentation, considering the characteristics of the vector used and the type of insertion. Studies presented by the company—some already published—indicate that:
- The OX5034 sequence in Aedes aegypti matches the intended design;
- The lineage does not contain residual sequences from the plasmid structure used in the transformation;
- A non-autonomous transposable element was used and has proven stable under various conditions;
- The insertion remains stable across generations and follows Mendelian inheritance patterns.
Documentation also shows that Aedes aegypti only mates with other individuals of the same species and exhibits limited dispersion in urban environments, although it can be transported long distances via land vehicles, ships, or even airplanes. Another biological aspect highlighted in the dossier and supported by scientific literature is the exotic origin of this species in the Dominican Republic, where it is confined to urban areas and does not provide ecosystem services protected under Dominican law or the Constitution.
The applicant investigated differences in mating behavior and competitiveness of the OX5034 line compared to field or wild-type populations in countries such as Brazil and Panama. The OX5034 technology has a history of safe use supported by multiple regulatory evaluations and successful releases in various countries. Its commercial approval by CTNBio in Brazil in May 2020 (Technical Opinion No. 6.946/2020) marked a significant milestone, followed by the EPA's authorization in the United States for releases in Florida (93167-EUP-2), and more recently, in Panama.
1) Potential toxicity or allergenicity of the recombinant protein present in the insect: Although the likelihood of a person being repeatedly bitten by transgenic mosquitoes is low due to the limited number of females released compared to the natural population, it is important to assess the allergenic potential of the proteins involved. After an exhaustive literature review and bioinformatic analyses conducted by the applicant—including source organisms such as Discosoma sp. and Acinetobacter sp. (Dossier, Book E, Section 6.2)—no scientific evidence was found to suggest that the proteins used in mosquito OX5034 have allergenic potential.
Therefore, although there is a minimal possibility of multiple bites by transgenic mosquitoes, the proteins involved do not pose an allergenic risk, and the probability of severe allergic reactions is negligible.
Therefore, although there is a minimal possibility of multiple bites by transgenic mosquitoes, the proteins involved do not pose an allergenic risk, and the probability of severe allergic reactions is negligible.
Regarding the potential toxicity of the DsRed2 and tTAV proteins present in the transgenic mosquito OX5034, no evidence of toxicity was found. DsRed2 has been widely used in various animal models without reported adverse effects. Although the original DsRed1 protein exhibited aggregation issues in embryonic stem cells, these limitations were overcome with the DsRed2 version.
As for tTAV—a synthetic protein derived from Escherichia coli and Herpes simplex virus—there are no indications of toxicity. Overall, the available scientific literature does not suggest that these proteins pose toxic risks to humans, animals, or the environment (Dossier, Book E, Section 6.1).
As for tTAV—a synthetic protein derived from Escherichia coli and Herpes simplex virus—there are no indications of toxicity. Overall, the available scientific literature does not suggest that these proteins pose toxic risks to humans, animals, or the environment (Dossier, Book E, Section 6.1).
2) Limited role as a pollinator:
Despite feeding on plant nectar, mosquitoes play a minor role in pollination (Clements, 1992). No interspecific interactions between the mosquito and any native flower species in the Dominican Republic are known or estimated to exist.
Despite feeding on plant nectar, mosquitoes play a minor role in pollination (Clements, 1992). No interspecific interactions between the mosquito and any native flower species in the Dominican Republic are known or estimated to exist.
3) Potential establishment of other vector species in breeding sites vacated by the removal of Ae. aegypti:
The use of transgenic mosquito OX5034 to control Aedes aegypti raises concerns that other vector mosquitoes, such as Culex spp. or Aedes albopictus, may occupy the freed breeding sites, potentially increasing disease transmission risks.
However, evidence shows that these species already coexist in the same environments without effective exclusion among them (Carrieri et al., 2003), and the removal of Ae. aegypti does not necessarily lead to an increase in other vector species.
In the Dominican Republic, Ae. aegypti is the most prevalent vector in Zika transmission areas (Alarcón-Elbal et al., 2021) and has demonstrated strong adaptability to environmental changes, including climate variations (Chadee & Martínez, 2016).
The use of transgenic mosquito OX5034 to control Aedes aegypti raises concerns that other vector mosquitoes, such as Culex spp. or Aedes albopictus, may occupy the freed breeding sites, potentially increasing disease transmission risks.
However, evidence shows that these species already coexist in the same environments without effective exclusion among them (Carrieri et al., 2003), and the removal of Ae. aegypti does not necessarily lead to an increase in other vector species.
In the Dominican Republic, Ae. aegypti is the most prevalent vector in Zika transmission areas (Alarcón-Elbal et al., 2021) and has demonstrated strong adaptability to environmental changes, including climate variations (Chadee & Martínez, 2016).
Impact on competing species:
The reduction of Ae. aegypti does not result in a significant increase in competitor species, as might be expected in other ecological contexts. In fact, the dominant presence of Ae. aegypti can displace native mosquito species, altering their population dynamics and affecting local biodiversity (K. Bennett et al., 2021; Fatma Bursalı et al., 2024; A. Lizuain et al., 2022).
The reduction of Ae. aegypti does not result in a significant increase in competitor species, as might be expected in other ecological contexts. In fact, the dominant presence of Ae. aegypti can displace native mosquito species, altering their population dynamics and affecting local biodiversity (K. Bennett et al., 2021; Fatma Bursalı et al., 2024; A. Lizuain et al., 2022).
4) Possible alteration in ecological interactions between Aedes aegypti and other species within local ecosystems:
Aedes aegypti is an African species introduced to the Americas through transatlantic trade (Powell, 2018). It is not native to the Dominican Republic or other countries in the region and does not play a fundamental role in local ecosystems.
It is a highly anthropophilic species, meaning its life cycle is closely linked to urban environments and artificial habitats such as homes and human-used water containers (León-Cortés & Gómez Velasco, 2018).
Aedes aegypti is an African species introduced to the Americas through transatlantic trade (Powell, 2018). It is not native to the Dominican Republic or other countries in the region and does not play a fundamental role in local ecosystems.
It is a highly anthropophilic species, meaning its life cycle is closely linked to urban environments and artificial habitats such as homes and human-used water containers (León-Cortés & Gómez Velasco, 2018).
Impact on the food chain:
It is consumed by various aquatic predators, such as fish, amphibians, and reptiles, although none of these rely exclusively on this species for food. Instead, these predators have a diverse diet that includes a wide variety of insects and larvae found in the environment (Vega et al., 2009).
It is consumed by various aquatic predators, such as fish, amphibians, and reptiles, although none of these rely exclusively on this species for food. Instead, these predators have a diverse diet that includes a wide variety of insects and larvae found in the environment (Vega et al., 2009).
For all the concerns outlined in this risk assessment, the probability of harm occurring and the magnitude of any potential damage are considered to be very low.
After a thorough analysis of the potential risks associated with the release of the genetically modified mosquito Aedes aegypti OX5034, it was concluded that there is no evidence to suggest this technology would cause harm to the environment, to people, or to other species. To reach this conclusion, possible pathways from potential hazards to actual damage were examined, and in all cases, no realistic routes were identified that would lead to meaningful harm.
Even in scenarios where concerns were raised—such as the idea that mosquitoes might play a role in plant pollination, or that other species might take over breeding sites—scientific data shows that the likelihood of these events happening is very low, and if they were to occur, their impact would be minimal.
Additionally, the OX5034 mosquito only releases males, which do not bite or transmit diseases, and the proteins they express are neither toxic nor allergenic. The mosquito also plays no significant role in natural ecosystems and is not a key food source for predators.
Therefore, based on the lack of plausible risk pathways, the very low probability of occurrence, and the limited impact such events might have, it is concluded that the risks associated with the release of OX5034 are negligible or insignificant, and do not pose any greater threat than the wild mosquitoes already present in the environment.
Based on the list of risks analyzed during the risk characterization stage, it is possible to conclude that the likelihood of potential risks materializing into actual harm is very low or negligible, and the effects would be marginal (i.e., the expected damage is minimal) for all concerns. The combination of these two parameters leads to insignificant risks for potential harms.
Based on the results of the environmental and human health risk assessment, it is concluded that the risks associated with the release of the genetically modified Aedes aegypti mosquito OX5034 in the Dominican Republic are acceptable and manageable, within the context of its proposed use for the control of vector-borne diseases. No significant adverse impacts were identified on biodiversity, human health, or local ecosystems. It is therefore recommended to authorize the controlled release of the genetically modified Aedes aegypti OX5034 mosquito in the Dominican Republic, given that the identified risks have been classified as acceptable and manageable according to the assessment performed. As a management measure, it is suggested to implement low-intensity post-release monitoring to confirm the absence of unforeseen effects. This monitoring should include the use of ovitraps in at least two release areas, with data collection on the presence of transgenic mosquitoes through fluorescence detection. The monitoring frequency will be weekly during the initial stage and will be reduced to monthly after four consecutive weeks without fluorescence detection, continuing until four consecutive months without transgene presence in the field have been completed. The results must be submitted in a final technical report to the competent regulatory authority.
EN
The current environmental legislation in the Dominican Republic clearly and primarily establishes the protection of the environment, biodiversity, and human health, as enshrined in the Constitution, the General Environmental and Natural Resources Law (Law No. 64-00), and the Sectoral Biodiversity Law (Law No. 333-15). Within this legal framework, the protection extends both to native and endemic species as well as to the natural ecosystems that serve as their habitat, along with essential resources such as water, soil, and air.
In the evaluation of the OX5034 event, the applicant and the technical team correctly identified that the receiving environment for the release of the modified mosquito consists mainly of urban and peri-urban areas, where Aedes aegypti is highly prevalent. The synanthropic and urban biology of this species, widely documented (OECD, 2018), supports that its life cycle is strongly associated with artificial environments created by humans, such as homes and domestic water containers. Thus, its establishment in natural environments like forests, agricultural areas, or natural water bodies is ruled out.
In this context, the primary protection objective in urban settings is human health, as it is the target species for control and the most exposed component. However, insectivorous organisms that could consume mosquito eggs or larvae—such as small reptiles, amphibians, and urban birds—were also considered. Nonetheless, these animals do not rely exclusively on Aedes aegypti as a food source, and their diet includes a wide variety of prey available in the urban environment, significantly reducing the risk of ecological impact.
Possible ecological interactions were also analyzed, such as the displacement of Aedes aegypti by other vector species (e.g., Aedes albopictus or Culex spp.) following the intervention, concluding that these species already coexist in the same breeding sites without effective competitive exclusion. Evidence shows that the elimination of Ae. aegypti does not necessarily lead to an increase in population density or epidemiological risk from other species (Carrieri et al., 2003; Alarcón-Elbal et al., 2021).
Regarding ecosystem impact, Aedes aegypti does not fulfill key roles such as pollination nor has coevolutionary relationships with the country’s native flora. Therefore, its reduction or elimination does not compromise relevant ecological processes. There is also no evidence of horizontal gene transfer or gene flow to other species, given that no sexually compatible species exist in the region.
Therefore, the characterization of the urban receiving environment, together with the specific biology of the modified mosquito and its self-limiting control strategy, allows the conclusion that the environmental risks derived from its release are negligible. OX5034 lacks the capacity to persist in the environment, does not pose a threat to biodiversity, nor significantly alters local ecological interactions. As a result, the application does not present significant challenges from the perspective of environmental risk assessment.
Nevertheless, all possible concerns related to the direct risks arising from the introduction of the GMO into the environment, identified based on documents submitted to the Ministry of Environment and Natural Resources—the national competent authority on biosafety—and the National Biosafety Commission (CONABIO), have been addressed taking into account the information provided by the applicant and the actively reviewed scientific publications, for their proper consideration in the potential final ruling.
Traditional molecular methods
The application for the release of the genetically modified mosquito Aedes aegypti OX5034, along with the corresponding risk assessment, is currently under review by the National Competent Authority. This procedure is part of the established national regulatory framework for living modified organisms, and a final decision on its authorization or rejection has not yet been issued. Therefore, the conclusions and recommendations contained in the available documentation should be interpreted as part of the ongoing scientific and technical evaluation process and remain subject to further review and deliberation by the competent authorities.
