Protective Antibodies for Malaria Identified by New Blood Test

The malaria pathogen Plasmodium falciparum carries poisonous sugar molecules called glycosylosphatidylinositols (GPIs) on its surface that can be individually identified. These sugar molecules are the dominant malarial toxins responsible for several pathologic processes associated with severe malaria. A person's immune system can form antibodies against these sugar molecules on the malaria pathogen, which protect against serious illness.

Blood samples taken from adults living in areas of Africa where malaria is endemic contain specific antibodies against particular GPIs. While infection is still possible despite the antibodies, the consequences are less serious. The immune system recognizes the poisonous sugar molecules as foreign bodies and blocks their toxic impact. Not living in high-risk areas, Europeans lack these antibodies. As soon as Europeans are infected with malaria, the number of antibodies increases significantly. Subsequently, there is a direct link between the amount of antibodies and protection against the disease.

A new blood test enables these antibodies to be detected. The method uses 64 pads comprising pinpoint dots affixed to glass slides. Every pad consists of several tiny heaps of different GPIs in varying concentrations. When blood serum is administered to such a pad, antibodies specifically bind to certain sugar molecules. Dyes then reveal to which GPIs the antibodies have become attached.

A chip developed in the laboratory of Prof. Peter Seeberger by a team of ETH Zurich and Swiss Tropical Institute (Zurich, Switzerland) scientists can use minute quantities of blood serum and sugar molecules to determine whether someone has formed particular antibodies against various GPIs. Large amounts of very pure GPIs can be produced synthetically in a laboratory, as the team demonstrated previously.

Using the information obtained from the chip, scientists can produce the specific sugar molecules that the immune system has to recognize. The findings should contribute to developing a sugar-based malaria vaccine and would be particularly beneficial to children in malaria-infested regions.

A report of the team's work was published online in the journal Nature Chemical Biology on March 2, 2008.


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