Antibodies to Escherichia coli-expressed C-terminal domains of Plasmodium falciparum variant surface antigen 2-chondroitin sulfate A (VAR2CSA) inhibit binding of CSA-adherent parasites to placental tissue

Infect Immun. 2013 Apr;81(4):1031-9. doi: 10.1128/IAI.00978-12. Epub 2013 Jan 14.

Abstract

Placental malaria (PM) is characterized by infected erythrocytes (IEs) that selectively bind to chondroitin sulfate A (CSA) and sequester in placental tissue. Variant surface antigen 2-CSA (VAR2CSA), a Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1) protein family member, is expressed on the surface of placental IEs and mediates adherence to CSA on the surface of syncytiotrophoblasts. This transmembrane protein contains 6 Duffy binding-like (DBL) domains which might contribute to the specific adhesive properties of IEs. Here, we use laboratory isolate 3D7 VAR2CSA DBL domains expressed in Escherichia coli to generate antibodies specific for this protein. Flow cytometry results showed that antibodies generated against DBL4ε, DBL5ε, DBL6ε, and tandem double domains of DBL4-DBL5 and DBL5-DBL6 all bind to placental parasite isolates and to lab strains selected for CSA binding but do not bind to children's parasites. Antisera to DBL4ε and to DBL5ε inhibit maternal IE binding to placental tissue in a manner comparable to that for plasma collected from multigravid women. These antibodies also inhibit binding to CSA of several field isolates derived from pregnant women, while antibodies to double domains do not enhance the functional immune response. These data support DBL4ε and DBL5ε as vaccine candidates for pregnancy malaria and demonstrate that E. coli is a feasible tool for the large-scale manufacture of a vaccine based on these VAR2CSA domains.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Animals
  • Antibodies, Protozoan / blood*
  • Antibodies, Protozoan / immunology
  • Antigens, Protozoan / genetics
  • Antigens, Protozoan / immunology*
  • Cell Adhesion
  • Chondroitin Sulfates / genetics
  • Chondroitin Sulfates / immunology*
  • Chondroitin Sulfates / metabolism
  • Escherichia coli / genetics
  • Female
  • Gene Expression
  • Humans
  • Infant, Newborn
  • Malaria / prevention & control*
  • Malaria Vaccines / administration & dosage
  • Malaria Vaccines / immunology*
  • Placenta / parasitology*
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology
  • Pregnancy
  • Protein Structure, Tertiary
  • Rats
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / immunology
  • Vaccines, Synthetic / administration & dosage
  • Vaccines, Synthetic / immunology

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Malaria Vaccines
  • Recombinant Fusion Proteins
  • VAR2CSA protein, Plasmodium falciparum
  • Vaccines, Synthetic
  • Chondroitin Sulfates