Vaccine Development May Be Spurred by Identification of Malaria Binding

Molecular parasitologists have identified a protein used by the malaria parasite Plasmodium falciparum to bind to human red blood cells.

Investigators from Virginia Commonwealth University (Richmond, USA) used a binding assay to examine the interaction between P. falciparum and human erythrocyte membrane proteins. In particular they looked at glycophorin B, a protein that projects through the thickness of the erythrocyte cell membrane. It is attached to oligosaccharides at the outer cell membrane surface and to contractile proteins (spectrin and actin) at the cytoplasmic surface.

Results published in the March 11, 2009, online edition of the journal Proceedings of the [U.S.] National Academy of Sciences (PNAS) revealed that attachment of the parasite to a receptor on glycophorin B was through the P. falciparum EBL-1 molecule. EBL-1 is a member of the Duffy-binding-like erythrocyte-binding protein (DBL-EBP) receptor family. The erythrocyte-binding domain, region 2 of EBL-1, expressed on CHO-K1 cells (Chinese ovary cells), bound normal red cells but not those modified to lack glycophorin B. In addition, normal red cells but not glycophorin B-null erythrocytes adsorbed native EBL-1 from P. falciparum culture supernatants.

"We have now identified how the parasite binds to glycophorin B on the red blood cells. Down the road, the EBL-1 molecule could be used as a vaccine target against malaria as part of a multivalent vaccine, or vaccine cocktail,” said first author Dr. Ghislaine Mayer, assistant professor of biology at Virginia Commonwealth University.

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