Subject(s)
Antigens, Protozoan , DNA, Protozoan/genetics , GTP-Binding Proteins/genetics , GTPase-Activating Proteins , Genes, Protozoan , N-Acetylneuraminic Acid/metabolism , Plasmodium falciparum/genetics , Amino Acid Sequence , Animals , DNA, Complementary , DNA, Protozoan/chemistry , GTP-Binding Proteins/chemistry , GTP-Binding Proteins/metabolism , Gene Expression , Membrane Proteins/genetics , Membrane Proteins/metabolism , Molecular Sequence Data , Plasmodium falciparum/growth & development , Plasmodium falciparum/pathogenicity , Polymerase Chain Reaction/methods , Protozoan Proteins/genetics , Protozoan Proteins/metabolism , RNA, Messenger/genetics , RNA, Messenger/metabolism , Reverse Transcriptase Polymerase Chain ReactionABSTRACT
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.
