Malaria parasites use camouflage to trick immune defences of pregnant women

Jul 11, 2011

Copenhagen University Hospital and the University of Copenhagen have discovered why malaria parasites are able to hide from the immune defences of expectant mothers, allowing the parasite to attack the placenta. The discovery is an important part of the efforts researchers are making to understand this frequently fatal disease and to develop a vaccine.

Staff member at CMP. Photo: Lars Hviid"We have found one likely explanation for the length of time it takes for the expectant mother's immune defences to discover the infection in the ," says Lea Barfod, MSc, who is working with Professor Lars Hviid at the Centre for Medical Parasitology, University of Copenhagen.

"The are able to assume a camouflage that prevents their recognition by the antibodies which would otherwise combat them. So although the immune system has all the weapons it needs to fight the infection of the placenta, these weapons are ineffectual simply because the enemy is hard to spot. Ironically the camouflage also consists of antibodies, but of a type that does not help to fight infection."

The malaria parasite at war with the immune system

One human being in twelve is infected with malaria. That means 500 million people are carrying the tiny parasite, and it kills a million of them a year. The disease costs so many lives because the parasite constantly outmanoeuvres the . It starts by hiding in the red blood cells. The immune system does not bother with these as the spleen usually filters defective blood cells.

To avoid this filter, the parasite ejects a protein hook which attaches to the inner wall of the blood vessel, and even if the immune system antibodies destroy one such hook, the parasite has more than sixty in its arsenal. One of them has evolved specially to attach to the placenta. While the war is being waged the parasite propagates and infects more and more , which are normally used for transporting and oxygen around the body.

Fighting from house to house

"In an advanced version of hide-and-seek the parasites keep looking for new ways of preventing the from recognising them. It is a kind of urban guerrilla war in which the fighting is conducted from house to house," says Lars Hviid.

"One example is the ability of the parasites to hide in the placenta. The first time an African woman conceives her placenta provides a new opportunity for the parasite to hide: a new house, so to speak, and in a way that prevents discovery by the immune system. It takes time for the immune defences to react to the new threat, and meanwhile the camouflaged parasite harms the woman and her unborn child."

The researchers are now going to study whether the also uses its camouflage at other stages of an infection.

"Perhaps it is not only the parasites in the placenta that are capable of hiding like this," Lars Hviid says.

"It takes the body a surprisingly long time to develop protection from Malaria, and perhaps the trick we have just discovered is part of the explanation. It is important for us to find out if this is the case in order to help us to understand in general, but also to help us in our efforts to develop a vaccination. We have plenty of work to be going on with," Lars Hviid concludes.

Lea Barfod and Lars Hviid's discovery has just been published in the Proceedings of the National Academy of Sciences.

Explore further: Cell division speed influences gene architecture

More information: Barfod, L., et al. (2011) 'Evasion of immunity to Plasmodium falciparum malaria by IgM masking of protective IgG epitopes in infected erythrocyte surface-exposed PfEMP1'. PNAS, published 11 July. DOI:10.1073/pnas.1103708108

Provided by University of Copenhagen

not rated yet
add to favorites email to friend print save as pdf

Related Stories

Research exposes new target for malaria drugs

Aug 04, 2008

The malaria parasite has waged a successful guerrilla war against the human immune system for eons, but a study in this week's Journal of Biological Chemistry has exposed one of the tricks malaria uses to hide from the immune ...

Malaria's newest pathway into human cells identified

Sep 24, 2010

Development of an effective vaccine for malaria is a step closer following identification of a key pathway used by the malaria parasite to infect human cells. The discovery, by researchers at The Walter and ...

Recommended for you

Cell division speed influences gene architecture

19 hours ago

Speed-reading is a technique used to read quickly. It involves visual searching for clues to meaning and skipping non-essential words and/ or sentences. Similarly to humans, biological systems are sometimes ...

Secret life of cells revealed with new technique

21 hours ago

(Phys.org) —A new technique that allows researchers to conduct experiments more rapidly and accurately is giving insights into the workings of proteins important in heart and muscle diseases.

In the 'slime jungle' height matters

22 hours ago

(Phys.org) —In communities of microbes, akin to 'slime jungles', cells evolve not just to grow faster than their rivals but also to push themselves to the surface of colonies where they gain the best access ...

Queuing theory helps physicist understand protein recycling

Apr 22, 2014

We've all waited in line and most of us have gotten stuck in a check-out line longer than we would like. For Will Mather, assistant professor of physics and an instructor with the College of Science's Integrated Science Curriculum, ...

User comments : 0

More news stories

When things get glassy, molecules go fractal

Colorful church windows, beads on a necklace and many of our favorite plastics share something in common—they all belong to a state of matter known as glasses. School children learn the difference between ...

FCC to propose pay-for-priority Internet standards

The Federal Communications Commission is set to propose new open Internet rules that would allow content companies to pay for faster delivery over the so-called "last mile" connection to people's homes.

SK Hynix posts Q1 surge in net profit

South Korea's SK Hynix Inc said Thursday its first-quarter net profit surged nearly 350 percent from the previous year on a spike in sales of PC memory chips.