Search for the Sialic Acid–Independent Receptor on Red Blood Cells for Invasion by Plasmodium falciparum

Abstract

BACKGROUND AND OBJECTIVES: Plasmodium falciparum uses multiple red blood cell (RBC) receptors and parasite ligands to invade RBCs. One pathway uses a sialic acid-independent protein or carbohydrate for invasion. The present study searches for this RBC receptor. MATERIALS AND METHODS: We determined whether antigen-negative and null RBCs (including PNH cells that lack all glycosylphosphatidyl inositol-linked proteins) could be invaded after neuraminidase treatment. We used two P. falciparum clones for the study: one that requires sialic acid for invasion and was an indication of removal of sialic acid and a second clone that can invade neuraminidase-treated RBCs. RESULTS: All neuraminidase-treated variant RBCs in this study were invaded. CONCLUSION: This study indicates that some molecule other than those studied (e.g., a carbohydrate) is the receptor for the sialic acid-independent pathway. This powerful tool for the identification of receptors for microorganisms should be used more extensively.