A portion of the Pf155/RESA antigen of Plasmodium falciparum is accessible on the surface of infected erythrocytes.

An investigation of antigens accessible to lactoperoxidase-catalysed cell surface iodination on intact Plasmodium falciparum-infected red blood cells (RBC) has identified a 125I-labelled antigen with an apparent size of about 155 kD. This labelled protein was specifically immunoprecipitated by the following antibodies: a rabbit antiserum and a mouse monoclonal antibody raised against a synthetic peptide comprising the 3',8-mer repeat EENVEHDA of the Pf155/RESA protein; a rabbit antiserum raised against a synthetic octapeptide comprising two copies of the 3',4-mer repeat EENV of the Pf155/RESA protein; and rabbit antisera against another synthetic peptide C(MYSNNNVED)2. The last antibody shows a strong reaction in asexual blood stage parasites with the Pf155/RESA antigen. While this antigen has been described previously as a submembrane component of the outer membrane of infected RBC, this report shows that at least part of its is accessible to the surface of both ring and late trophozoite-infected erythrocytes.