Selection of peptides recognized by human antibodies against the surface of Plasmodium falciparum-infected erythrocytes.

In an attempt to identify mimotopes of the surface antigens of P. falciparum-infected erythrocytes (iRBC), antibodies were eluted from iRBC that had been treated with a pool of sera from malaria-infected individuals (IHS), and were used to screen a phage display library (PDL). After repeated panning of the PDL on immobilized antibodies, phage that selectively bound to IHS were accumulated. Of 23 randomly chosen clones that were sequenced, 13 individual sequences were detected at varying frequencies and 3 of the 13 sequences had homology with membrane proteins known to exist on iRBC. The majority of phage clones (7 out of 8 clones) selected after the 4th panning bound selectively to IgG in IHS. Specific binding of the selected phage to IgG in IHS was also confirmed using 24 IHS and 11 sera from uninfected individuals. One phage clone was the most frequently found in the sequenced clones after the 4th panning, and the binding of this clone to IgG in all IHS was greater than in any serum from uninfected individuals. A rabbit antiserum against the peptide expressed on the clone specifically recognized the surface of iRBC and resulted in iRBC haemolysis.