[Identification of the binding site on glycophorin A for Plasmodium falciparum EBA-175].

Objective: To identify the binding site on glycophorin A (GPA) for EBA-175 to provide clue for developing short peptide vaccine and therapeutic agents against Plasmodium falciparum.

Methods: With the recombinant protein of EBA-175 as the target molecule, the mimetic peptides of GPA were screened from a 12-mer random peptide library. Three rounds of biopanning were carried out, and enzyme-linked immunosorbent assay (ELISA), competitive ELISA, Dot-ELISA and Western blotting used to evaluate the binding between the phage-borne peptides and EBA-175. The insert DNA sequences of positive clones were determined and their amino acid sequences deduced.

Results: Thirty clones from the third round were randomly selected, of which 27 were found positive by sandwich ELISA. Competitive ELISA proved that most of the phage-borne peptides could competitively inhibit the binding of antibody (EBA-175 Ab) with EBA-175. Analysis of DNA and amino acid sequences indicated that 24 positive phage clones contained the conservative sequence of IRR, which was highly homologous with the 114-116 amino acids of GPA.

Conclusion: These phage-displayed peptides can bind with EBA-175, and the amino acid sequence IRR might play an important role in the binding between EBA-175 and GPA.