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GM mosquitoes could help control malaria in Africa but their development must involve local scientists, write Paul Eggleston and Mamadou Coulibaly.
About 3.3 billion people in 109 countries are under threat of malaria infection. The disease kills one million people each year, most of them children in Sub-Saharan Africa, and it can cut a country’s financial growth by a significant amount.
In the face of increasing insecticide and drug resistance and the lack of an effective vaccine, we desperately need to explore new ways of tackling this devastating disease. Mosquitoes that are genetically engineered to be resistant to malaria and deployed in high-risk areas would provide a valuable tool for controlling the disease in Africa.
Much progress has been made in recent years. It is now possible to engineer the genome of Anopheles gambiae, the principal malaria-carrying mosquito, and the first genetically modified (GM) strains that limit malaria transmission have been tested in the laboratory.
Of course, much more remains to be done. Engineering a mosquito that cannot transmit malaria at all will most likely mean introducingcombinations of genes that kill parasites in different ways — to ensure that no parasites survive and to limit their chances of developing resistance.
And replacing native mosquitoes with GM malaria-resistant ones will also require a ‘gene drive’ strategy to ensure that the genetic changes spread through natural populations, instead of dying out.
Engaging at local level
But a major obstacle is that all these technological advances have taken place in developed countries. The science, ethics and logistics of using GM mosquitoes to control malaria also demand local research and development in disease endemic areas in the developing world.
To make the science work and to deliver a real health benefit, we must work with local strains of mosquitoes and parasites. Only so much can be done with the ‘colonised’ species held in the United Kingdom or United States. Sooner or later the technology must be tested under more natural conditions.
Ethically, it would neither be reasonable nor practical to develop a malaria-resistant GM mosquito in the North and ‘parachute’ it into Africa as a novel control strategy. It would have little chance of acceptance.
The logistics of delivering a successful outcome demand the involvement of local scientists and stakeholders. They are much more likely to understand the biology of their native organisms and the concerns of people living under threat of the disease.
Local scientists may not yet have the skills needed to deliver novel GM mosquito technology but they can, and should, be trained in its use. Only in this way can we expect them to be fully committed to the potential use of such control strategies.
Fit for purpose
With support from the Wellcome Trust, we have now embarked on the first programme to transfer the technology for GM mosquito research to Africa. The project is a partnership between Keele University in the United Kingdom and the Malaria Research and Training Centre (MRTC) at the University of Bamako in Mali, which has broad experience of the biology and genetics of local mosquitoes and of malaria transmission in West Africa.
The programme will build capacity in three important areas: genetic engineering of local mosquitoes; gene products that kill malaria parasites; and fitness and competitiveness of GM mosquitoes.
We have already recruited and begun training staff in Bamako and built new laboratory facilities there to contain GM mosquitoes. As the work develops, and with the key support of the MRTC and local people, we hope to establish a field station outside the university to test the effectiveness and fitness of GM mosquitoes in contained trials.
This phased approach, from laboratory through to contained field trials, will be essential to provide efficacy and safety data before any potential releases into the natural environment.
Of course, any such releases must be guided by appropriate regulations and biosafety legislation. At the international level, the WHO is already developing a regulatory framework, following a technical consultation, and is due to make recommendations within a year.
Individual nations, particularly those where malaria is endemic, will also need to develop and enhance their biosafety legislation so that informed choices can be made. In Mali, MRTC scientists are helping to draft local biosafety and biosecurity laws for GM organisms and can provide regional assistance to other countries through membership of the African Biosafety Organization.
Moving research on GM mosquitoes forward will be difficult, and some scientists have reservations about the approach. But mostly even they acknowledge that it is the one with the greatest potential. We should strive to make it happen.
Paul Eggleston is professor of molecular entomology and deputy director of the Institute for Science and Technology in Medicine at Keele University, United Kingdom.
Mamadou Coulibaly is head of the Vector Genomics and Proteomics Laboratory at the Malaria Research and Training Centre, University of Bamako, Mali.