Plasmodium yoelii: Effects of red blood cell modification and antibodies on the binding characteristics of the 235-kDa rhoptry protein

The 235-kDa rhoptry protein of the rodent malaria parasite Plasmodium yoeli i yoelii was shown to bind to the surface of mouse red blood cells in a cal cium-independent process, using a erythrocyte-binding assay. This binding i s affected by modification of the surface of the red blood cells by enzymat ic treatment. Chymotrypsin and trypsin but not neuraminidase treatment of t he erythrocytes significantly reduced the binding of the 235-kDa proteins. The binding of an unrelated 135-kDa protein was abolished by treatment with chymotrypsin. Although the 235-kDa proteins bind to both reticulocytes and mature red blood cells, the binding to mature cells was more pronounced. I n the presence of hyperimmune infection serum or specific polyclonal antibo dies to the 235-kDa protein its binding to erythrocytes was reduced, furthe r demonstrating the specificity of this ligand-receptor interaction. (C) 20 00 Academic Press.