Identification of a strain-specific malarial antigen exposed on the surface of Plasmodium falciparum-infected erythrocytes.

Open Access
Publisher Website
Google Scholar
Abstract
Strain-specific antigens with Camp and St. Lucia strains of P. falciparum of MW .apprx. 285,000 and .apprx. 260,000, respectively were identified. 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 [Aotus monkey] erythrocytes (IE). The proteins are accessible to lactoperoxidase-catalyzed radioiodination of intact IE. The radioiodinated proteins were cleaved by low concentrations of trypsin (0.1 .mu.g/ml). These antigens were immunoprecipitated after addition of immune sera to intact IE. The strain-specific immunoprecipitation of these proteins correlated with the capacity of immune sera to block cytoadherence of IE in a strain-specific fashion. 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 was proven to be a malarial protein exposed on the erythrocyte surface.