An End to Malaria?

Using genetic modification, researchers have bred a mosquito that cannot transmit the disease.

A female Anopheles mosquito, any one of the 25 species that exist worldwide, needs blood to produce eggs. When it bites a human or animal infected with malaria, it also ingests the malarial parasite— Plasmodium.  The parasite cells try and squeeze out through her midgut. Most are destroyed by her immune cells, a few survive clinging to the outside stomach wall and start replicating in a capsule. In ten days or so the capsule bursts, releasing parasite cells that make their way to her salivary glands. The next creature she bites is infected with the disease. 

One way to end malaria is to do away with the replication of the Plasmodium parasite within the mosquito. “If you want to effectively stop the spreading of the malaria parasite, you need mosquitoes that are no less than 100 per cent resistant to it. If a single parasite slips through and infects a human, the whole approach will be doomed to fail,” says Michael Riehle, who led the research published in the journal Public Library of Science Pathogens. “It was known that the Akt enzyme is involved in the mosquito’s growth rate and immune response … ,” Riehle says. “So we went ahead with (a) genetic construct to see if we can ramp up Akt function…’’ The enzyme not only strengthens the mosquito immune system, it also cuts down its lifespan. “Only the oldest mosquitoes are able to transmit the parasite,’’ Riehle adds, “If we can reduce the lifespan of the mosquitoes, we can reduce the number of infections.” 

Using the Anopheles stephensi, a species prevalent in India, they engineered a piece of genetic code that leads to the permanent activation of Akt. Mosquitoes carrying two copies of this altered gene lost their ability to act as malaria vectors altogether, with not a single Plasmodium capsule being able to form. 

As of now, these mosquitoes exist in a highly secured lab environment. Any decision to replace the wild population with these does not lie with the scientists.

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Hartosh Singh Bal