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GROUNDBREAKING: Gene drives trial for malaria control in the pipeline

30 May 2024
GROUNDBREAKING: Gene drives trial for malaria control in the pipeline
A snip from the Malaria Journal featuring Ifakara's seasoned scientist, Dickson Lwetoijera as contributor to the study. GRAPHICS: Ifakara Communications

In the ongoing fight against malaria, scientists are gearing up to use innovative gene drive technology to control mosquito populations. This technology involves modifying mosquito genes to prevent them from spreading diseases like malaria.

Details of the scientists' considerations for the innovative technology were published recently on the Malaria Journal. Contributors include scientists from academic and research institutions in the UK, Burkina Faso, USA, Uganda and Tanzania, including Ifakara Health Institute scientist Dickson Lwetoijera.

Plans for implementation, field trials

The paper outlines the plan to adapt and implement gene-drive technology, with the first field trials expected to begin within the next five years.

These trials, known as “low-threshold gene drive systems,” aim to determine whether altering mosquito genes can effectively stop the spread of malaria. This strategy targets the Anopheles mosquito species—the primary carriers of malaria—by releasing genetically modified mosquitoes into the wild to influence their populations and reduce malaria transmission.

“Sustainable reductions in African malaria transmission require innovative tools for mosquito control. One proposal involves the use of low-threshold gene drive in Anopheles vector species, where a ‘causal pathway’ would be initiated…” wrote the scientists.

Challenges in malaria control

In Africa, malaria still poses a significant health challenge with millions affected each year. Traditional control measures, such as insecticides and bed nets, are effective but have limitations, including the development of insecticide-resistant mosquito populations. This has driven scientists to explore new methods, including gene drive technology.

Multi-step process for field trials

For the proposed field trials, the approach will involve a multi-step process. Firstly, the approach will involve the release of a gene drive system in targeted mosquito species, leading to its transmission to subsequent generations.

This initial process aims to increase the frequency and spread of a genetic trait that reduces the mosquitoes' ability to transmit the malaria parasite. As the gene drive system reaches fixation in the targeted mosquito populations, the incidence and prevalence of malaria are expected to decrease.

Discussions on design, monitoring strategies

In their proposal, the scientists also discuss the design and monitoring strategies for these initial field trials, drawing on insights from past successful implementation of biological and vector control tools, such as insecticides, Wolbachia, larvicides, and attractive-toxic sugar bait systems.

To determine the effectiveness of the gene drive in reducing malaria transmission, the scientists recommend that the initial phase of the trials focus on the gene drive's ability to increase in frequency and spread within the target mosquito populations. If successful, they will proceed to subsequent phases to assess the broader impact, including entomological (mosquito-related) and epidemiological (disease-related) outcomes.

“While effective conduct of initial field trials of low-threshold gene drive systems may be favored when objectives are simple…initial trials also should be designed and implemented to provide sufficient breadth and depth of information, experience, and confidence to optimize field releases for later, more complex, and larger field trials involving more robust epidemiological assessments.”

Deploying advanced tools for field trials

The trials will also employ advanced statistical and modeling tools to aid in selecting optimal trial locations, designing robust experiments, and monitoring the trials in real time. These tools are essential for making informed decisions and ensuring the trials are effective and safe.

Optimism in gene drive technology

Concluding their proposal, the scientists expressed optimism about the potential of gene drive technology, stating, “Collectively, the considerations here advance the realization of developer ambitions for the first field trials of low-threshold gene drive for malaria vector control within the next 5 years.” If successful, these trials could mark a significant step towards eradicating malaria.

Scientists involved in the study

The study was led by John Connolly from Imperial College London, UK alongside colleagues Austin Burt, George Christophides, Tibebu Habtewold, Penelope Hancock, Andrew McKemey and Nikolai Windbichler – all from the same Institution.

Other contributors include Abdoulaye Diabate from Institut de Recherche en Sciences de la Santé, Anthony James from the University of California, Jonathan Kayondo from Uganda Virus Research Institute (UVRI), Dickson Lwetoijera from Ifakara Health Institute, Alphaxard Manjurano from National Institute for Medical Research (NIMR), Michael Santos from Foundation for the National Institutes of Health, and Filippo Randazzo from Leverage Science, LLC, USA.

Read the publication here: https://malariajournal.biomedcentral.com/articles/10.1186/s12936-024-04952-9#Abs1