ISOLATION FROM PHAGE DISPLAY LIBRARIES OF SINGLE-CHAIN VARIABLE FRAGMENT ANTIBODIES THAT RECOGNIZE CONFORMATIONAL EPITOPES IN THE MALARIA VACCINE CANDIDATE, APICAL MEMBRANE ANTIGEN-1

Phage display of single chain variable fragment (scFv) antibodies is a powerful tool for the selection of important and useful antibody spec ificities. We have constructed such a library from mice protected from malaria challenge by immunization with recombinant Plasmodium chabaud i DS apical membrane antigen (AMA-1). Panning on refolded AMA-1 enrich ed a population of scFvs which specifically bound the antigen. The sin gle chain antibodies recognize conformational epitopes on AMA-1 from t he P. chabaudi DS strain but not on AMA-1 of the 556KA strain of P. ch abaudi. A subset of the antibody fragments recognized AMA-1 from the h uman malaria parasite Plasmodium falciparum. Nucleotide sequencing rev ealed that at least four unique scFv genes were selected by the pannin g procedure. These scFv antibodies are valuable reagents for probing t he structure and function of AMA-1 and will be used to test the feasib ility of using recombinant antibodies in a passive immunization therap y against malaria.