title: Antigenicity and immunogenicity of the N-terminal 33-kDa processing fragment of the Plasmodium falciparum merozoite surface protein 1, MSP1: implications for vaccine development.
abstract: 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.
authors.affiliation: Department of Biochemistry, Chinese University of Hong Kong, Shatin, Hong Kong.
authors.forename: Don
authors.initials: D
authors.lastname: Yuen
authors.forename: Wai-Hang
authors.initials: WH
authors.lastname: Leung
authors.forename: Randy
authors.initials: R
authors.lastname: Cheung
authors.forename: Caryn
authors.initials: C
authors.lastname: Hashimoto
authors.forename: Sui Fung
authors.initials: SF
authors.lastname: Ng
authors.forename: Walter
authors.initials: W
authors.lastname: Ho
authors.forename: George
authors.initials: G
authors.lastname: Hui
mesh_terms: D000483:Alleles; D000818:Animals; D000913:Antibodies, Protozoan / Q000032:analysis / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D019084:Fluorescent Antibody Technique, Indirect; D017780:Malaria Vaccines / Q000276:immunology*; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D010446:Peptide Fragments / Q000276:immunology*; D010963:Plasmodium falciparum / Q000276:immunology*; D011817:Rabbits; D022223:Vaccines, Subunit / Q000276:immunology; D014614:Vaccines, Synthetic / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D017780:Malaria Vaccines; D020066:Merozoite Surface Protein 1; D010446:Peptide Fragments; D022223:Vaccines, Subunit; D014614:Vaccines, Synthetic