title: Recognition of variant Rifin antigens by human antibodies induced during natural Plasmodium falciparum infections.
abstract: Antibodies from individuals living in areas where malaria is endemic are known to react with parasite-derived erythrocyte surface proteins. The major immunogenic and clonally variant surface antigen described to date is Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP-1), which is encoded by members of the multicopy var gene family. We report here that rifin proteins (RIF proteins), belonging to the largest known family of variable infected erythrocyte surface-expressed proteins, are also naturally immunogenic. Recombinant RIF proteins were used to analyze the antibody responses of individuals living in an area of intense malaria transmission. Elevated anti-rifin antibody levels were detected in the majority of the adult population tested, whereas the prevalence of such antibodies was much lower in malaria-exposed children. Despite the high degree of diversity between rif sequences and the high gene copy number, it appears that P. falciparum infections can induce antibodies that cross-react with several variant rifin molecules in many parasite isolates in a given community, and the immune response is most likely to be stable over time in a hyperendemic area. The protein was localized by fluorescence microscopy on the membrane of ring and young trophozoite-infected erythrocytes with antibodies from human immune sera with specificities for recombinant RIF protein.
authors.affiliation: Department of Parasitology, Institute for Tropical Medicine, University of Tübingen, Germany.
authors.forename: Mohamed S
authors.initials: MS
authors.lastname: Abdel-Latif
authors.forename: Ayman
authors.initials: A
authors.lastname: Khattab
authors.forename: Christoph
authors.initials: C
authors.lastname: Lindenthal
authors.forename: Peter G
authors.initials: PG
authors.lastname: Kremsner
authors.forename: Mo-Quen
authors.initials: MQ
authors.lastname: Klinkert
mesh_terms: D000293:Adolescent; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D000940:Antigenic Variation; D000953:Antigens, Protozoan / Q000235:genetics / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004912:Erythrocytes / Q000378:metabolism / Q000469:parasitology; D006801:Humans; D007223:Infant; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology; D008875:Middle Aged; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000276:immunology*; D015800:Protozoan Proteins / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000276:immunology
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015800:Protozoan Proteins; D011994:Recombinant Proteins