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Genetically-modified mosquitoes against dengue fever

Aedes_aegypti

After malaria, dengue fever is the second-most widespread mosquito-borne disease in the world. It is an extremely painful – and sometimes fatal – disease that affects millions of people each year. One of the biggest problems is that there is currently no cure for dengue, nor any way to protect a population from getting sick in the first place. An effective vaccine has so far proven elusive because dengue is caused by four different types of the virus.
The mosquito that spreads dengue fever – Aedes aegypti – has proven tricky to keep in check. However, British scientist Luke Alphey has come up with a way to use the mosquito as a tool to control its own species. By programming an extra gene into the mosquitos’ DNA, he has ensured that the resulting mosquito larvae never reach reproductive maturity.
Miniscule amounts of genetically modified DNA is injected into mosquito eggs, and the larvae inside absorb it into their cells, where it is subsequently copied into their genomes. The majority of the larvae won’t accept the foreign DNA, but only one out of a thousand eggs needs to absorb the DNA to breed an entire colony.
After the DNA has been copied into every cell, it spurs the production of a protein called tTAV that effectively stops the cells from working properly.
In captivity the mosquitoes are fed a diet containing tetracycline, an antidote that stops tTAV protein from working. This allows them to mature and breed as normal.
In the wild, the absence of tetracycline results in tTAV production which ties up the cell’s normal processes so genes that are essential for the mosquito cells to survive are switched off.
With successive releases, the invasive mosquito population is reduced, leading to fewer biting mosquitos and lower risk of disease transmission. This technique can reduce mosquito numbers by more than 90% in target populations – far better than current methods – offering viable mosquito control that does not rely on toxic pesticides.