title: Identification of a strain-specific malarial antigen exposed on the surface of Plasmodium falciparum-infected erythrocytes.
abstract: We have identified strain-specific antigens with Camp and St. Lucia strains of P. falciparum of Mr approximately 285,000 and approximately 260,000, respectively. These strain-specific antigens were metabolically labeled with radioactive amino acids, indicating that they were of parasite origin rather than altered host components. These proteins had the properties of a molecule exposed on the surface of infected erythrocytes (IE). First, the proteins are accessible to lactoperoxidase-catalyzed radioiodination of IE. Second, the radioiodinated proteins were cleaved by low concentrations of trypsin (0.1 microgram/ml). Third, these antigens were immunoprecipitated after addition of immune sera to intact IE. Fourth, the strain-specific immuno-precipitation of these proteins correlated with the capacity of immune sera to block cytoadherence of IE in a strain-specific fashion. Fifth, the strain-specific antigen had detergent solubility properties (i.e., insolubility in 1% Triton X-100, solubility in 5% sodium dodecyl sulfate) similar to the variant antigen of P. knowlesi, which has been proven to be a malarial protein exposed on the erythrocyte surface.
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000032:analysis* / Q000276:immunology; D001029:Aotus trivirgatus; D002448:Cell Adhesion / Q000187:drug effects; D004912:Erythrocytes / Q000276:immunology / Q000469:parasitology*; D007106:Immune Sera / Q000494:pharmacology; D007163:Immunosorbent Techniques; D008545:Melanoma; D008565:Membrane Proteins / Q000097:blood; D008970:Molecular Weight; D010963:Plasmodium falciparum / Q000276:immunology*; D013045:Species Specificity; D014357:Trypsin / Q000494:pharmacology
chemical_list: D000954:Antigens, Surface; D007106:Immune Sera; D008565:Membrane Proteins; D014357:Trypsin