Mass spectrometric analysis of Plasmodium falciparum erythrocyte membrane protein-1 variants expressed by placental malaria parasites.

Surface proteins from Plasmodium falciparum are important malaria vaccine targets. However, the surface proteins previously identified are highly variant and difficult to study. We used tandem mass spectrometry to characterize the variant antigens (Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1)) expressed on the surface of malaria-infected erythrocytes that bind to chondroitin sulfate A (CSA) in the placenta. Whereas PfEMP1 variants previously implicated as CSA ligands were detected, in unselected parasites four novel variants were detected in CSA-binding or placental parasites but not in unselected parasites. These novel PfEMP1 variants require further study to confirm whether they play a role in placental malaria.