From: The Times

A GENETIC "cloaking device" with which the malaria parasite hides itself from the human immune system has been discovered by scientists, paving the way for new drugs against the disease.

Research in Australia has revealed how the Plasmodium falciparum organism intermittently switches off certain genes so the immune system can not learn to recognise it and fight it off.

The findings suggest drugs that target this genetic mechanism could provide a new method of treating malaria by lifting its molecular mask and enabling the body's defences to destroy the parasite.

Further work is needed to unlock details of how the disguise works before drug development becomes workable.

Malaria, which rivals HIV-AIDS as the world's most deadly infectious condition, is particularly damaging because the immune system finds it hard to mount an effective response.

Throughout its lifetime, P.falciparum regularly changes the version of the protein PfEMP1 that it deposits on infected cells.

By the time the body has recognised this protein and made antibodies to it, the parasite has moved on to a different version, thus escaping detection and attack.

In the study, published yesterday in the journal Cell, a team led by Alan Cowman and Brendan Crabb, of the Walter and Eliza Hall Institute of Medical Research in Melbourne, found the parasite switches off particular genes.

It has been understood since the mid-1990s that more than 50 so-called "var" genes produce the different versions of the PfEMP1 protein but only one is active at any one time.

Over the course of a malaria infection, P.falciparum cycles through the var genes to remain one step ahead of the immune system.

The researchers identified that another protein, SIR2, seemed to play a part in determining which var genes were active and which were switched off.

This protein effectively wraps the DNA of the inactive var genes into tight packages to prevent them from forming proteins and having an effect.

Dr Cowman said a better understanding of the process could lead to the design of drugs that prevent this, ensuring all var genes were expressed at once, giving the immune system a good look at all the PfEMP1 proteins it might encounter.

This would enable the production of antibodies to fight malaria early and prevent the worst effects of the disease.