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

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.