Internal mechanism that kills malaria in mosquitoes found

Updated: Jun 08, 2012, 11:50 AM IST

Washington: For the first time, scientists have identified a series proteins in mosquitoes that transduce a signal enabling the insects to fight off infection from the parasite that causes malaria in humans, a finding they say could lead to new treatments for the killer disease.

The findings could lead to an effective invention towards controlling malaria which kills over 800,000 people, mostly children, each year around the world, the researchers said.

According to Johns Hopkins Malaria Research Institute in the US, these proteins are known as immune deficiency (Imd) pathway signal transducing factors, are analogous to an electrical circuit.

As each factor is switched on or off, it triggers or inhibits the next, finally leading to the launch of an immune response against the malaria parasite, they found.

The new study, published in the journal PLoS Pathogens, builds upon earlier work of the research team, in which they found that silencing one gene of this circuit, called Caspar, activated Rel2, an Imd pathway transcription factor of the Anopheles gambiae mosquito.

The activation of Rel2 turns on the effectors known as TEP1, APL1 and FBN9 that kill malaria-causing parasites in the mosquito`s gut.

More significantly, this study discovered the Imd pathway signal transducing factors and effectors that will mediate a successful reduction of parasite infection at their early ookinete stage, as well as in the later oocyst stage when the levels of infection were similar to those found in nature.

"Identifying and understanding how all of the players work is crucial for manipulating the Imd pathway as an invention to control malaria. We now know which genes can be manipulated through genetic engineering to create a malaria resistant mosquito," said study author George Dimopoulos of the Johns Hopkins Bloomberg School of Public Health.

For the study, the researchers used a RNA interference method to "knock down" the genes of the Imd pathway. As the components were inactivated, the researchers could observe how the mosquito`s resistance to parasite infection would change.

"Imagine a string of Christmas lights or other circuit that will not work when parts aren`t aligned in the right sequence. That is how we are working with the mosquito`s immune system," explained Dimopolous.

"We manipulate the molecular components of the mosquito`s immune system to identify the parts necessary to kill the malaria parasites," he added.