A sequence in subdomain 2 of DBL1α of Plasmodium falciparum erythrocyte membrane protein 1 induces strain transcending antibodies

PLoS One. 2013;8(1):e52679. doi: 10.1371/journal.pone.0052679. Epub 2013 Jan 15.

Abstract

Immunity to severe malaria is the first level of immunity acquired to Plasmodium falciparum. Antibodies to the variant antigen PfEMP1 (P. falciparum erythrocyte membrane protein 1) present at the surface of the parasitized red blood cell (pRBC) confer protection by blocking microvascular sequestration. Here we have generated antibodies to peptide sequences of subdomain 2 of PfEMP1-DBL1α previously identified to be associated with severe or mild malaria. A set of sera generated to the amino acid sequence KLQTLTLHQVREYWWALNRKEVWKA, containing the motif ALNRKE, stained the live pRBC. 50% of parasites tested (7/14) were positive both in flow cytometry and immunofluorescence assays with live pRBCs including both laboratory strains and in vitro adapted clinical isolates. Antibodies that reacted selectively with the sequence REYWWALNRKEVWKA in a 15-mer peptide array of DBL1α-domains were also found to react with the pRBC surface. By utilizing a peptide array to map the binding properties of the elicited anti-DBL1α antibodies, the amino acids WxxNRx were found essential for antibody binding. Complementary experiments using 135 degenerate RDSM peptide sequences obtained from 93 Ugandan patient-isolates showed that antibody binding occurred when the amino acids WxLNRKE/D were present in the peptide. The data suggests that the ALNRKE sequence motif, associated with severe malaria, induces strain-transcending antibodies that react with the pRBC surface.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Amino Acid Sequence
  • Animals
  • Antibodies, Protozoan / immunology*
  • Antibodies, Protozoan / metabolism
  • Antibody Specificity
  • Antigens, Protozoan / chemistry
  • Antigens, Protozoan / immunology*
  • Child, Preschool
  • Cross Reactions / immunology
  • Epitopes / chemistry
  • Epitopes / immunology
  • Erythrocytes / immunology
  • Erythrocytes / parasitology
  • Female
  • Humans
  • Immunoglobulin G / immunology
  • Immunoglobulin G / metabolism
  • Infant
  • Male
  • Models, Molecular
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / immunology
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology
  • Protein Binding / immunology
  • Protein Conformation
  • Protein Interaction Domains and Motifs / immunology*
  • Protozoan Proteins / chemistry
  • Protozoan Proteins / immunology*
  • Rabbits
  • Rats

Substances

  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Epitopes
  • Immunoglobulin G
  • Peptides
  • Protozoan Proteins
  • erythrocyte membrane protein 1, Plasmodium falciparum

Grants and funding

This work was supported by Swedish Research Council (VR), The Swedish Academy of Sciences (KVA, Söderberg foundation), Karolinska Institutet-DPA and the EU Network of Excellence EviMalar. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.