MICE IMMUNIZED WITH A SYNTHETIC PEPTIDE CONSTRUCT CORRESPONDING TO ANEPITOPE PRESENT ON A PLASMODIUM-FALCIPARUM ANTIGEN ARE PROTECTED AGAINST PLASMODIUM-CHABAUDI CHALLENGE

Inhibitory monoclonal antibody (MoAb) 8E7/55 recognizes a parasitophor ous vacuole membrane (PVM) antigen in Plasmodium falciparum. Previous studies have identified the epitope, DNNLVSGP, recognized by the MoAb. A synthetic peptide containing this sequence was synthesized and coup led to diphtheria toxoid (DT) and was found capable of generating anti bodies when used as an immunogen in mice which recognize the native an tigen exp-1. In this study we demonstrate the ability of the MoAb and antisera generated against the peptide construct to recognize a 54 kD PVM antigen in Plasmodium chabaudi. The P. chabaudi antigen is synthes ized in trophozoites and released to the surrounding culture media out side the parasitized erythrocyte. Mice immunized with the peptide conj ugate are protected when challenged with a lethal strain of P. chabaud i. Protection in the mice correlated with the antibody titre prior to challenge. If the PVM antigen,from P. chabaudi is a homologue of exp-1 from P. falciparum, then these experiments may provide a guide to the antibody titres required in human trials before antibody mediated pro tection could be expected. The discovery that a PVAF localized antigen is secreted into the surrounding in vitro culture media provides us w ith a valuable model system for further investigation of protein traff icking pathways in malaria-infected erythrocytes.