Amino terminal peptides of the ring infected erythrocyte surface antigen of Plasmodium falciparum bind specifically to erythrocytes

The Ring-Infected Erythrocyte Surface Antigen (Pf155/RESA) sequence was che mically synthesized: in fifty four 20-mer sequential peptides, covering the entire protein, each of which was tested in erythrocyte binding assays. Pe ptides 6671 and 6673, corresponding to residues 141-160 and 181-200, respec tively, presented a high specific binding activity to erythrocytes with aff inity constants of 190 nM and 105 nM respectively. Their binding was sensit ive to previous enzymatic treatment of erythrocytes. A region of peptide 66 73 has been identified, very recently, as a B-cell epitope, target of neutr alizing antibodies (Siddique AB, Iqbal J, Ahlborg N, Wahlin FB, Perlmann P, Berzins K. Antibodies to nonrepeat sequences Of antigen Pf155/ RESA of Pla smodium falciparum inhibit parasite growth in vitro. Parasitol Res 1998;84: 485-91). The critical residues for erythrocyte binding for peptide 6671 (MT DVNR YR YSNNYEAIPHIS) and for peptide 6673 (LGRSGGDI/KKMQTLWDEIM) were reco gnized. Based on these data, the presence of five functional regions of RES A is postulated. (C) 2000 Elsevier Science Ltd. All rights reserved.