Monday 23 October 2017

Scientists move closer to global eradication of killer malaria bug

Steve Connor in London

The complete global eradication of malaria is now a strong possibility after a discovery by scientists.

They have discovered the critical component of human red blood cells vital for the malaria parasite to complete its lifecycle within the human body -- in effect, the parasite's "Achilles' heel" has been identified.

This means it should be possible to design a vaccine that blocks the parasite's development within an infected person, which, researchers believe, should prevent both the disease and its mosquito-borne transmission. Nearly a million people a year die from malaria, mostly children under five living in sub-Saharan Africa.

Scientists have spent decades trying to devise vaccines that protect people against infection or can control the parasite's development once it is inside the body. However, the complexity of the parasite's lifecycle has frustrated the design of effective vaccines.

But now, said Julian Rayner of the Sanger Institute in Cambridge, the crucial protein "lock" on the surface of human red cells that allows the mosquito to insert its "key" and gain entry has been found.

"The interaction (between malaria parasite and red blood cell) that we have found has the potential to be the basis of a vaccine that would save millions of lives," Dr Rayner said.

"This is possibly the most exciting vaccine target for the past 10 years."

The work focuses on the second phase of the malaria lifecycle in the human body, after it leaves the liver to invade the red blood cells.

Protein

Scientists at the Sanger Institute were able to identify a human protein, called basigin, on the surface membrane of the human red blood cells that the parasite appears to need to unlock the membrane and invade the cell.

"The malaria parasite shuttles between mosquitoes and humans. But the stage that actually causes the symptoms of the disease is where the parasite invades human red blood cells," Dr Rayner said.

"It has to get inside a red blood cell to divide, spread and multiply -- it's essential for the parasite's survival. But it's also a potential target for attack."

Once the scientists had identified the key protein "receptor" on the membrane of the red cells, they devised experiments to see if it was possible to block the interaction between malaria parasite and cell.

They succeeded with antibodies designed to recognise and stick to the corresponding receptor protein on the parasite, blocking the "key" used by the parasite to unlock red cells.

"We can show that if we use antibody against the receptor we can completely block all detectable invasion by the parasite," said Gavin Wright.

"We have done experiments where we've raised antibodies against the parasite protein and again we've shown very strong inhibition of the invasion process.

"As a starting point for vaccine development, you couldn't hope for better." (© Independent News Service)

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