Induction of cross-reactive immune responses to NTS-DBL-1alpha/x of PfEMP1 and in vivo protection on challenge with Plasmodium falciparum

Vaccine. 2006 Aug 28;24(35-36):6140-54. doi: 10.1016/j.vaccine.2006.05.030. Epub 2006 Jun 5.

Abstract

The interactions of Plasmodium falciparum infected erythrocytes parasitized red blood cells (pRBC) with endothelial receptors and erythrocytes are mediated by multiple Duffy-binding like (DBL) and cysteine-rich interdomain region (CIDR) domains harboured in the Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). The success of a subunit vaccine based on PfEMP1 depends on its ability to elicit cross-reactive responses to a substantial number of PfEMP1 variants. We have here evaluated serological PfEMP1 cross-reactivity by immunizing rats with phylogenetically diverse recombinant NTS-DBL-1alpha/x fusion domains from the 3D7 genome parasite emulsified in Montanide ISA 720. Cross-reactivity was elicited to these diverse DBL-1alpha/x domains as measured by ELISA and by immunoblotting. Employing a novel in vivo model of human infected erythrocyte sequestration, immunized animals were challenged with the FCR3S1.2 clone and cross-protection in terms of reduction in lung sequestration amounting to approximately 50% was demonstrated. Our results suggest that immunization with phylogenetically distant DBL-1alpha/x variants, can elicit partial cross-protection to challenge with the parasites harbouring a distant variant. These observations have implications for the design of multi-component vaccines against P. falciparum malaria.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Antibody Formation
  • Cloning, Molecular
  • Cross Reactions / physiology
  • Enzyme-Linked Immunosorbent Assay
  • Gene Expression
  • Glutathione Transferase
  • Immunization
  • Immunoblotting
  • Malaria, Falciparum / prevention & control*
  • Plasmodium falciparum / genetics
  • Plasmodium falciparum / immunology*
  • Protein Structure, Tertiary
  • Protozoan Proteins / genetics
  • Protozoan Proteins / immunology*
  • Rats
  • Rats, Sprague-Dawley
  • Recombinant Fusion Proteins
  • Vaccines, Synthetic / adverse effects
  • Vaccines, Synthetic / therapeutic use*

Substances

  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • Vaccines, Synthetic
  • Glutathione Transferase