Malaria, a mosquito-borne parasitic disease, is responsible for around one million childhood deaths each year. Many millions of other children are infected and suffer debilitating sickness because of the disease. Nearly half the world’s population - about 3 billion people - lives in areas affected by malaria.

A research team led by Dr James Beeson at WEHI has made discoveries about how the human immune system combats malaria and how the malaria parasite can evade the immune response. These findings open up new approaches for developing a multi-component vaccine to prevent malaria. Currently, there is no vaccine available and malaria is becoming resistant to drugs used for treatment.

Malaria parasites produce specific types of proteins that stick to the surface of red blood cells, enabling the parasites to drill into the cells and start multiplying. Emerging in large numbers from these infected blood cells, the parasites cause serious damage to blood vessels in organs such as the brain and lungs. This can lead to coma and death.

Researchers at WEHI and the Kenya Medical Research Institute have been studying immune responses among children and adults living in a malaria-affected area in the east African country, Kenya. The researchers have shown that malaria proteins that stick to red blood cells are important targets of immune attack. The immune system of people living in malaria-affected areas produces antibodies that block the function of these malaria proteins and therefore block the ability of malaria to infect red blood cells.

However, malaria has two classes of proteins that stick to the red blood cell, and by switching the expression or use of these different proteins, malaria infects red blood cells through different pathways to avoid the immune response. This means that the immune response is not effective and takes a long time to develop.

These findings provide important insights into how the evasive strategies of malaria can be combated and point the way to new approaches to develop vaccines against malaria. The results suggest that a vaccine against the classes of malaria proteins that stick to the red blood cell would be an effective way of blocking malaria infection in the bloodstream. But an effective vaccine would need to target the multiple members of these proteins and to block the different ways malaria has to infect red blood cells.

The research is published in Journal of Clinical Investigation, December 2007.