Plasmodium falciparum merozoite surface protein 1 (MSP-1)-MSP-3 chimeric protein: immunogenicity determined with human-compatible adjuvants and induction of protective immune response

Infect Immun. 2010 Feb;78(2):872-83. doi: 10.1128/IAI.00427-09. Epub 2009 Nov 23.

Abstract

A chimeric gene, MSP-Fu(24), was constructed by genetically coupling immunodominant, conserved regions of the two leading malaria vaccine candidates, Plasmodium falciparum merozoite surface protein 1 (C-terminal 19-kDa region [PfMSP-1(19)]) and merozoite surface protein 3 (11-kDa conserved region [PfMSP-3(11)]). The recombinant MSP-Fu(24) protein was produced in Escherichia coli cells and purified to homogeneity by a two-step purification process with a yield of approximately 30 mg/liter. Analyses of conformational properties of MSP-Fu(24) using PfMSP-1(19)-specific monoclonal antibody showed that the conformational epitopes of PfMSP-1(19) that may be critical for the generation of the antiparasitic immune response remained intact in the fusion protein. Recombinant MSP-Fu(24) was highly immunogenic in mice and in rabbits when formulated with two different human-compatible adjuvants and induced an immune response against both PfMSP-1(19) and PfMSP-3(11). Purified anti-MSP-Fu(24) antibodies showed invasion inhibition of P. falciparum 3D7 and FCR parasites, and this effect was found to be dependent on antibodies specific for the PfMSP-1(19) component. The protective potential of MSP-Fu(24) was demonstrated by in vitro parasite growth inhibition using an antibody-dependent cell inhibition (ADCI) assay with anti-MSP-Fu(24) antibodies. Overall, the antiparasitic activity was mediated by a combination of growth-inhibitory antibodies generated by both the PfMSP-1(19) and PfMSP-3(11) components of the MSP-Fu(24) protein. The antiparasitic activities elicited by anti-MSP-Fu(24) antibodies were comparable to those elicited by antibodies generated with immunization with a physical mixture of two component antigens, PfMSP-1(19) and PfMSP-3(11). The fusion protein induces a protective immune response with human-compatible adjuvants and may form a part of a multicomponent malaria vaccine.

MeSH terms

  • Adjuvants, Immunologic*
  • Animals
  • Antibodies, Protozoan / immunology
  • Antigens, Protozoan / immunology*
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescent Antibody Technique
  • Humans
  • Malaria Vaccines / immunology*
  • Malaria, Falciparum / immunology
  • Malaria, Falciparum / prevention & control
  • Merozoite Surface Protein 1 / genetics*
  • Mice
  • Plasmodium falciparum
  • Protozoan Proteins / immunology*
  • Rabbits
  • Recombinant Proteins / immunology

Substances

  • Adjuvants, Immunologic
  • Antibodies, Protozoan
  • Antigens, Protozoan
  • Malaria Vaccines
  • Merozoite Surface Protein 1
  • Protozoan Proteins
  • Recombinant Proteins
  • merozoite surface protein 3, Plasmodium