Solid experimental evidence indicates that EBA-175 is used as a ligand by the Plasmodium falciparum merozoite to bind
to human RBC, via different binding processing fragments. Using synthetic peptides and specific receptor-ligand
interaction methodology, we have identified 6 high-activity binding sequences from the EBA-175 CAMP strain; peptide
1758 (KSYGTPDNIDKNMSLIHKHN), located in the so-called region I for which no binding activity has been
reported before, peptides 1779 (NIDRIYDKNLLMIKEHILAI) and 1783 (HRNKKNDKLYRDEWWKVIKK),
located in region II, in a sub-region known as 5′ Cys F2, previously reported as being a binding region, and peptides 1814
(DRNSNTLHLKDYRNEENERH), 1815 (YTNQNINISQERDLQKHGFH) and 1818 (NNNFNNIPSRYNLYDKKLDL),
in region III–V where antibodies inhibit merozoite invasion of erythrocytes. The affinity constants were
between 60 and 180 nM and the critical amino acids involved in the binding were identified. The binding of these peptides
to enzyme-treated RBC was analysed; binding of peptide 1814, located in the III–V region, was found to be sialic acid
dependent. Some of these high binding peptides were able to inhibit in vitro merozoite invasion and to block the binding
of recombinant RII-EBA to RBC. Several of these peptides are located in regions recognized by protective immune
clusters of merozoites (ICMs) eluted antibodies.