Cytoadherence of Plasmodium falciparum-infected erythrocytes plays an important role in the pathogenesis of cerebral malaria. The identity of cell surface molecules on parasitized erythrocytes involved in cytoadherence is of great interest to understand the molecular basis of this mechanism. Peptide sequences derived from exofacial loops of the erythrocyte antigen band 3 from parasitized erythrocytes have previously been shown to inhibit cytoadherence. We now report that a non-repeated region of Pf155/RESA (residues 213–218) contains a hexapeptide motif being highly homologous to cytoadherence inhibitory sequences from band 3. Synthetic peptides containing the hexapeptide motif of Pf155/RESA inhibited the binding of P.falciparum-infected erythrocytes to melanoma cells in vitro. Furthermore, individuals residing in malaria-endemic areas have antibodies reactive with epitopes involving these motifs in band 3 and in Pf155/RESA.

Antibodies to a non-repeat region of the Plasmodium falciparum antigen Pf155/RESA were investigated for their capacity to inhibit parasite cytoadherence to melanoma cells and parasite growth in vitro. The activities of these antibodies were studied since the target region in Pf155/RESA includes a cytoadherence-related motif also found in loop 3 and 7 of human erythrocyte band 3 protein. Overlapping multiple antigen peptides (MAPs) together spanning residues 199–220 of Pf155/RESA were used to raise antibodies in rabbits. Analysis of the fine specificity of these antibodies revealed that antibodies raised against largely overlapping sequences displayed highly different specificity patterns. Similarly, striking differences were seen when analysing the biological effect of antibodies to these MAPs. Antibodies to the cytoadherence-related motif of Pf155/RESA, as well as antibodies raised against a MAP based on a corresponding band 3 motif, inhibited cytoadherence but not parasite growth. In contrast, antibodies to sequences adjacent to the Pf155/RESA cytoadherence motif inhibited parasite growth in vitro but had no effect on cytoadherence.