Antigenicity and immunogenicity of the N-terminal 33-kDa processing fragment of the Plasmodium falciparum merozoite surface protein 1, MSP1: implications for vaccine development

Vaccine. 2007 Jan 5;25(3):490-9. doi: 10.1016/j.vaccine.2006.07.053. Epub 2006 Aug 10.


The Plasmodium falciparum merozoite surface protein 1 (MSP1), MSP1-42 and MSP1-19 are protective malaria vaccines. MSP1-42 is cleaved to form MSP1-33 and MSP1-19. The role of MSP1-33 in immunity is unclear. We investigated the antibody responses to MSP1-33; and to MSP1-33Trunc, in which major conserved sequences were excised. While anti-MSP1-33 antibodies were subdominant in the anti-MSP1-42 responses, immunizations with MSP1-33 or MSP1-33Trunc induced high levels of antibodies reactive with MSP1-42 or whole merozoites. Anti-MSP1-33 and anti-MSP1-33Tunc antibodies crossreacted with both allelic forms of MSP1-42. Anti-MSP1-33 sera were ineffective in inhibiting parasite growth in vitro; but they significantly enhanced the activities of sub-optimal concentrations of the inhibitory anti-MSP1-42 sera. Thus, immunization strategies with MSP1-based vaccines may benefit from co-induction of anti-MSP1-33 responses to enhance efficacy and potency.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Animals
  • Antibodies, Protozoan / analysis
  • Antibodies, Protozoan / biosynthesis
  • Enzyme-Linked Immunosorbent Assay
  • Fluorescent Antibody Technique, Indirect
  • Malaria Vaccines / immunology*
  • Merozoite Surface Protein 1 / immunology*
  • Peptide Fragments / immunology*
  • Plasmodium falciparum / immunology*
  • Rabbits
  • Vaccines, Subunit / immunology
  • Vaccines, Synthetic / immunology


  • Antibodies, Protozoan
  • Malaria Vaccines
  • Merozoite Surface Protein 1
  • Peptide Fragments
  • Vaccines, Subunit
  • Vaccines, Synthetic