Erythrocyte-binding antigen 175 mediates invasion in Plasmodium falciparum utilizing sialic acid-dependent and -independent pathways

Proc Natl Acad Sci U S A. 2003 Apr 15;100(8):4796-801. doi: 10.1073/pnas.0730883100. Epub 2003 Apr 2.

Abstract

The Plasmodium falciparum erythrocyte-binding antigen 175 (EBA-175) is a ligand for merozoite invasion into human erythrocytes that binds to glycophorin A in a sialic acid-dependent manner. P. falciparum strain W2mef depends on sialic acid for invasion of erythrocytes, whereas 3D7 is sialic acid-independent. We generated parasites that lack expression or express truncated forms of EBA-175 in W2mef and 3D7. Lack of EBA-175 expression in W2mef parasites was associated with a switch to sialic acid-independent invasion. 3D7 parasites lacking expression of EBA-175 showed no alteration in their ability to utilize sialic acid-independent pathways. Strikingly, both W2mef and 3D7 parasites lacking EBA-175 expression invaded chymotrypsin-treated erythrocytes inefficiently compared with the parental lines. This loss of function suggests that the EBA-175/glycophorin A ligand-receptor interaction is the major chymotrypsin-resistant invasion pathway. Parasite lines with truncated EBA-175 had invasion phenotypes equivalent to parasites lacking expression of EBA-175. The EBA-175 ligand is functional in erythrocyte invasion by merozoites that utilize either sialic acid-dependent or -independent invasion pathways. This finding suggests a model where a minimal affinity supplied by multiple ligand-receptor interactions is required for successful invasion and has implications for EBA-175 as a malaria vaccine candidate.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / metabolism*
  • Base Sequence
  • Carrier Proteins / genetics
  • Carrier Proteins / immunology*
  • Carrier Proteins / metabolism*
  • DNA, Protozoan / genetics
  • Erythrocytes / metabolism
  • Erythrocytes / parasitology
  • Glycophorins / metabolism
  • Humans
  • In Vitro Techniques
  • Models, Biological
  • Mutation
  • N-Acetylneuraminic Acid / metabolism*
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology*
  • Plasmodium falciparum / pathogenicity*
  • Protein Binding
  • Protozoan Proteins / genetics
  • Protozoan Proteins / immunology*
  • Protozoan Proteins / metabolism*
  • Recombinant Proteins / genetics
  • Recombinant Proteins / immunology
  • Recombinant Proteins / metabolism

Substances

  • Antigens, Protozoan
  • Carrier Proteins
  • DNA, Protozoan
  • Glycophorins
  • Protozoan Proteins
  • Recombinant Proteins
  • erythrocyte-binding antigen 175, Plasmodium
  • N-Acetylneuraminic Acid