Infectious Disease

The WHO is updating the guidelines for testing genetically modified mosquitoes

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Kolaczinski does not report any relevant financial information.

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Researchers have investigated the use of genetically engineered mosquitoes as a potential control method for vector-borne diseases.

Just last month, Oxitec began releasing its genetically modified (GM), self-limiting male Aedes aegypti mosquitoes in the Florida Keys in hopes of reducing mosquito populations.

Photo of the mosquito Aedes aegypti, 2018;  Photo credit: James Gathany

The WHO has published new guidelines for testing genetically modified mosquitoes.
Source: Adobe Stock.

This month, the WHO published the second edition of its guidelines on GM mosquito testing (GMM) and updated the guidelines that were originally published in 2014. We talked to them Jan. Kolaczinski, PhD, MSc, Head of the Department of Vector Control and Insecticide Resistance in the WHO Global Malaria Program on the new guidelines and their importance for researchers.

Healio: What are the main topics that the guidelines relate to?

Kolaczinski:: Much advances in research have been made to improve the feasibility of GMM interventions, and many different ways of using this approach have been explored. The characteristics of different GM strategies need to be considered, how they might be tested and how they might be used. The updated guidance describes best practices for safety and effectiveness testing, ethical obligations and obligations, and regulatory oversight for different types of GMM at each stage of the test path for different types of GMM.

Healio: What has changed in the world of GMM Research since the first manual was written in 2014, and how have the guidelines changed to reflect this?

Kolaczinski:: The first two articles using CRISPR / Cas for gene propulsion in mosquitoes were published in late 2015 and early 2016 after the guidelines were published. Previously, people tried to use naturally occurring propulsion mechanisms with limited success. Very rapid advances have been made in gene propulsion with the advent of CRISPR / Cas and many types are now envisaged, including those that are self-limiting and self-sustaining. See the instructions for examples of these different types of changes. Along with significant technical advances, much more attention has been paid to risk assessment, ethical and governance issues for these new types of technologies. We have become much more sophisticated in our thinking about stakeholder engagement in general, and perhaps particularly in the context of risk assessment. All of these changes are reflected in the updated guidance.

Healio: What technologies are already being tested in the wild and what other technologies are most advanced? Development?

Kolaczinski:: Self-limiting mosquitoes produced by Oxitec are the most advanced in terms of on-site assessment. The first version of Oxitec’s non-viable GMM for population suppression was tested in small versions until 2014. Now, tests have been carried out on a larger scale and Oxitec has moved on to a more efficient, second generation product that is fertile and that fertile let the suppressive effect in the local mosquito population last a little longer but eventually go away. Releases from fertile male Aedes aegypti are currently being evaluated in Florida. An anopheline mosquito construct is not yet available for field assessment.

Target Malaria conducted a very small field release of a male-sterile version of its technology in Burkina Faso as part of its local capacity building activities in preparation for future trials.

To date, no GMM containing GMM has been released in the area. The developers have made great strides in creating candidates for gene drive approaches and demonstrating effectiveness in the laboratory or insectarium. However, it is recognized that there is a lot of additional groundwork to be done before field testing, as described in the guidance.

Wolbachia’s work is much more advanced and has provided a lot of hands-on experience that has been informative.

A strategy to suppress the population using radiation instead of genetic manipulation to sterilize mosquitoes was tested in the field.

Healio: What does the manual say? special about gen-drive modified mosquitoes?

Kolaczinski:: The updated guidelines include a much broader look at the advances and challenges facing genetically engineered mosquitoes. The impact of different types of gene drives on the step-by-step test path proposed in 2014 is discussed. For example, it explains how the propagation properties of gene drives must be taken into account when designing field tests. It discusses how characteristics of spread and persistence in the environment should be taken into account in the risk assessment, reviews existing guidance and recommendations from other sources on the subject, and recommends how risk assessment and management should be addressed at each testing phase. Relevant precedents for regulatory surveillance of genetically engineered mosquitoes will also be reviewed. This includes not only the regulation of biosafety resulting from the Cartagena Protocol, but also the regulation of biological control agents that persist and spread in the environment, and of course the health regulatory pathways applicable to public health instruments. As mentioned earlier, the updated guidance outlines best practices for safety and efficacy testing, ethical obligations and obligations, and regulatory oversight for different types of GMM, including different types of genetically engineered mosquitoes, at each stage of the testing pathway.

Healio: Can GMMs end mosquito-borne disease?

Kolaczinski:: We have learned from experience that vector-borne diseases are very resilient, which is why we need as many interventions as possible to address them in the form of intervention packages tailored to specific contexts. At this point, no one expects GMMs to be a silver bullet to end malaria or arboviral infections. However, they have certain theoretical advantages that make them very attractive as a complement to existing or other planned interventions. For example, they offer comprehensive protection that is independent of socio-economic status or proximity to medical facilities. They don’t require people to change their behavior in order to be effective. They can reach hard-to-find mosquito breeding grounds and should be effective against outdoor vectors and bites that are not attacked by long-lasting insecticidal nets and indoor sprays. and they are suitable for both urban and rural disease transmission. Self-sustaining individuals should provide permanent protection that reduces delivery costs, enables them to function in conditions where other interventions are difficult to sustain (e.g. during civil unrest or the COVID-19 pandemic), and by providing a contribution to eradicate disease provide continued protection from resurgence in regions where the disease has been cleared. Given these potential benefits and the fact that GMM technologies now appear technically feasible but understands the need for a possible thorough assessment of possible risks on a case-by-case basis, WHO has taken the position that these technologies require further investigation.

References:

Diabaté A. Results of months of surveillance after the first release of genetically engineered mosquitoes in Africa. https://targetmalaria.org/results-from-months-of-monitoring-following-the-first-release-of-non-gene-drive-genetically-modified-mosquitoes-in-africa/#:~:text= Target% 20Malaria% 20Burkina% 20Faso% 20is, Release% 20over% 202019% 20and% 202020. Accessed on May 24, 2021.

Gantz VM et al. Proc Natl Acad Sci USA 2015; doi: 10.1073 / pnas.1521077112.

Hammond A et al. Nat Biotechnol. 2016; doi: 10.1038 / nbt.3439.

Oxitec. The pioneering mosquito-transmitting project begins in the Florida Keys. https://www.oxitec.com/de/news/landmark-project-to-control-disease-carrying-mosquitoes-kicks-off-in-the-florida-keys. Accessed May 24, 2021.

WHO. Evaluation of Genetically Modified Mosquitoes for Control of Vector-borne Diseases. https://www.who.int/publications/i/item/9789240013155. Accessed May 24, 2021.

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Omar S. Akbari, PhD)

Omar S. Akbari, PhD

This guide provides a prudent path to safely developing and testing innovative genetic technologies to control mosquitoes. As the WHO statement shows, vector-borne diseases lead to significant morbidity and mortality that are disproportionately high in poorer populations. Current approaches are not enough; Therefore, there is an urgent need to test new technologies to combat these diseases. There are many innovative genetic technologies currently in development, many of which may offer long-lasting life-saving solutions. These WHO guidelines provide a necessary framework to inform future research and development for which these technologies can advance safely and carefully, taking into account potential risks and benefits, safety, ethics, affordability and effectiveness.

Omar S. Akbari, PhD

Associate Professor of Cell and Developmental Biology

Department of Life Sciences

University of California, San Diego

Disclosure: Akbari reports to co-found Agragene, a manufacturer of sterile male insects to replace chemical pesticides.

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