RECOGNITION OF PHAGE-EXPRESSED PEPTIDES CONTAINING ASX-PRO SEQUENCES BY MONOCLONAL-ANTIBODIES PRODUCED AGAINST PLASMODIUM-FALCIPARUM CIRCUMSPOROZOITE PROTEIN

The immunodominant region of the Plasmodium falciparum circumsporozoit e protein is comprised mainly of a series of tetrapeptide repeats that can, depending on the starting cadence chosen, be described as (NANP) (n), (ANPN)(n), (NPNA)(n) or (PNAN)(n) in one-letter amino acid code, Data from several studies suggest that the NPNA cadence alone is struc turally correct, in that each NPNA tetrapeptide effectively forms a st ructural unit initiated by an Asx-Pro turn, To explore this idea furth er and to assess the immunological relevance of peptide conformation a s it relates to the cadence of these tetrapeptide repeats, we used ELI SA to compare the abilities of monoclonal antibodies (MAbs) produced a gainst P.falciparum sporozoites to recognize repeat-related heptapepti des expressed on the surface of filamentous bacteriophage. Having incl uded representatives of both NANP and NPNA cadences and other peptides in which the number and location of Asx-Pro sequences varied, we prov ide evidence that Asx-Pro sequences play an important role in peptide conformation and antibody recognition, that peptide conformation is in fluenced by the cadence of the tetrapeptide repeats and that peptide c onformation is important to the abilities of these MAbs to recognize t heir epitopes.