Search for the sialic acid-independent receptor on red blood cells for invasion by Plasmodium falciparum

Objectives: Plasmodium falciparum uses multiple red blood cell (RBC) recept ors and parasite ligands to invade RBCs, One pathway uses a sialic acid-ind ependent protein or carbohydrate for invasion. The present study searches f or this RBC receptor, Materials and Methods: We determined whether antigen- negative and null RBCs (including PNH cells that lack all glycosylphosphati dyl inositol-linked proteins) could be invaded after neuraminidase treatmen t. 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 sec ond clone that can invade neuraminidase-treated RBCs, Results: All neuramin idase-treated variant RBCs in this study were invaded. Conclusion: This stu dy indicates that some molecule other than those studied (e.g., a carbohydr ate) is the receptor for the sialic acid-independent pathway. This powerful tool for the identification of receptors for microorganisms should be used more extensively.