title: A novel DBL-domain of the P. falciparum 332 molecule possibly involved in erythrocyte adhesion.
abstract: Plasmodium falciparum malaria is brought about by the asexual stages of the parasite residing in human red blood cells (RBC). Contact between the erythrocyte surface and the merozoite is the first step for successful invasion and proliferation of the parasite. A number of different pathways utilised by the parasite to adhere and invade the host RBC have been characterized, but the complete biology of this process remains elusive. We here report the identification of an open reading frame (ORF) representing a hitherto unknown second exon of the Pf332 gene that encodes a cysteine-rich polypeptide with a high degree of similarity to the Duffy-binding-like (DBL) domain of the erythrocyte-binding-ligand (EBL) family. The sequence of this DBL-domain is conserved and expressed in all parasite clones/strains investigated. In addition, the expression level of Pf332 correlates with proliferation efficiency of the parasites in vitro. Antibodies raised against the DBL-domain are able to reduce the invasion efficiency of different parasite clones/strains. Analysis of the DBL-domain revealed its ability to bind to uninfected human RBC, and moreover demonstrated association with the iRBC surface. Thus, Pf332 is a molecule with a potential role to support merozoite invasion. Due to the high level of conservation in sequence, the novel DBL-domain of Pf332 is of possible importance for development of novel anti-malaria drugs and vaccines.
authors.affiliation: Department of Parasitology, Mycology and Environmental Microbiology (PMV), Swedish Institute for Infectious Disease Control (SMI), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Moll
authors.forename: Arnaud
authors.initials: A
authors.lastname: Chêne
authors.forename: Ulf
authors.initials: U
authors.lastname: Ribacke
authors.forename: Osamu
authors.initials: O
authors.lastname: Kaneko
authors.forename: Sandra
authors.initials: S
authors.lastname: Nilsson
authors.forename: Gerhard
authors.initials: G
authors.lastname: Winter
authors.forename: Malin
authors.initials: M
authors.lastname: Haeggström
authors.forename: Weiqing
authors.initials: W
authors.lastname: Pan
authors.forename: Klavs
authors.initials: K
authors.lastname: Berzins
authors.forename: Mats
authors.initials: M
authors.lastname: Wahlgren
authors.forename: Qijun
authors.initials: Q
authors.lastname: Chen
mesh_terms: D000818:Animals; D002448:Cell Adhesion; D004912:Erythrocytes / Q000166:cytology* / Q000469:parasitology; D005091:Exons; D006801:Humans; D007438:Introns; D010963:Plasmodium falciparum / Q000378:metabolism* / Q000502:physiology; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D015800:Protozoan Proteins; C073415:antigen Pf332, Plasmodium