Genetic engineering, when planned and executed correctly, has huge potential to help improve conditions on a global scale. This may be through more efficient food production or research into better healthcare. In one interesting case, the insertion of a gene into mosquitoes could improve the health of millions. Genetically modified (GM) mosquitoes are to be used on a commercial scale in Brazil to help reduce the population of mosquitoes carrying the dengue microbe. Dengue affects 50 – 100 million individuals worldwide, and whilst drugs and vaccines are being researched, in the meantime, original approaches such as GM are crucial in managing dengue where cases are highest.
Oxitec, a biotechnology company based in Abingdon UK, have inserted a gene into mosquitoes which causes their sterility. Whilst the engineered insects can mate with wild females and produce offspring, they are technically defined as sterile because this offspring is unable to reach sexual maturity, and therefore pass on the dengue microbe to humans. Oxitec have also ingeniously inserted a fluorescent tag into the mosquitoes called DsRed. This tag allows them to monitor the spread of their sterile gene. In turn they can carefully consider how many GM mosquitoes are needed and where their release is most effective. Therefore this innovative method of control can be continually improved upon over time.
The GM mosquitoes are about to take their bold leap from small field studies to large scale production. This week a factory based in Campinas, Brazil, has opened in order to mass produce Oxitec’s engineered insects. The road towards making this mass production a reality however, has been filled with careful research and studies to ensure that their release is safe to both humans and the environment. Over 150 generations of the mosquito species Aedes aegypti (the primary carrier of the dengue microbe) have been produced and it has remained highly stable. The gene is safe for human exposure and the food chain will continue to be secure.
Field studies have shown a significant increase in the gene in wild populations of mosquitoes. A paper published in Nature (2012) followed their release on the Cayman Islands reporting a peak of 88% of eggs carrying the DsRed marker used to identify the presence of the sterile gene. Other studies at dengue high areas such as Brazil and Malaysia have shown similar promising results. Whilst cases of dengue have remained the same in humans in these small studies, researchers are confident that on a larger scale the health benefits will soon follow as the sterile gene spreads in the mosquito population.
Following the anticipated success of Brazil’s mass production and subsequent release, more GM mosquitoes will be released in other dengue hot spots around the world. GM organisms are not the only solution and locals have been removing the mosquito’s habitat of large open waters. Combined with a continued effort into vaccine research, and providing better medical care for individuals who contract dengue, the journey to a healthier, dengue free world may be shorter than expected. The use of GM mosquitoes to reduce cases of dengue isn’t the only application. Oxitec has high hopes to use similar technology on the Anopheles mosquito which carries malaria. Greater research is needed to better understand the intricacies of malaria and its numerous stages and hosts. However, in time, engineering these insects might be just as pivotal in the development of dengue control. Oxitec is a paragon of genetic engineering, proving that with a novel approach and careful consideration over safety, taking advantage of such technology may greatly improve global health.
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