title: Epitopes of anti-RIFIN antibodies and characterization of rif-expressing Plasmodium falciparum parasites by RNA sequencing.
abstract: Variable surface antigens of Plasmodium falciparum have been a major research focus since they facilitate parasite sequestration and give rise to deadly malaria complications. Coupled with its potential use as a vaccine candidate, the recent suggestion that the repetitive interspersed families of polypeptides (RIFINs) mediate blood group A rosetting and influence blood group distribution has raised the research profile of these adhesins. Nevertheless, detailed investigations into the functions of this highly diverse multigene family remain hampered by the limited number of validated reagents. In this study, we assess the specificities of three promising polyclonal anti-RIFIN antibodies that were IgG-purified from sera of immunized animals. Their epitope regions were mapped using a 175,000-peptide microarray holding overlapping peptides of the P. falciparum variable surface antigens. Through immunoblotting and immunofluorescence imaging, we show that different antibodies give varying results in different applications/assays. Finally, we authenticate the antibody-based detection of RIFINs in two previously uncharacterized non-rosetting parasite lines by identifying the dominant rif transcripts using RNA sequencing.
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.|Department of Microbiology and Immunology, National University of Singapore, Singapore.
authors.forename: Jun-Hong
authors.initials: JH
authors.lastname: Ch'ng
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Madle
authors.initials: M
authors.lastname: Sirel
authors.affiliation: Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.
authors.forename: Arash
authors.initials: A
authors.lastname: Zandian
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Maria
authors.initials: M
authors.lastname: Del Pilar Quintana
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Sherwin
authors.initials: S
authors.lastname: Chun Leung Chan
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Moll
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
authors.forename: Asa
authors.initials: A
authors.lastname: Tellgren-Roth
authors.affiliation: Center for Biomembrane Research, Department of Biochemistry and Biophysics, Stockholm University, Stockholm, Sweden.
authors.forename: IngMarie
authors.initials: I
authors.lastname: Nilsson
authors.affiliation: Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.
authors.forename: Peter
authors.initials: P
authors.lastname: Nilsson
authors.affiliation: Affinity Proteomics, Science for Life Laboratory, School of Biotechnology, Royal Institute of Technology (KTH), Stockholm, Sweden.
authors.forename: Ulrika
authors.initials: U
authors.lastname: Qundos
authors.affiliation: Department of Microbiology, Tumor and Cell Biology (MTC), Karolinska Institutet, Stockholm, Sweden.
authors.forename: Mats
authors.initials: M
authors.lastname: Wahlgren
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000276:immunology*; D020869:Gene Expression Profiling; D006041:Goats; D008565:Membrane Proteins / Q000276:immunology*; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000276:immunology*; D011817:Rabbits; D017423:Sequence Analysis, RNA
chemical_list: D000913:Antibodies, Protozoan; D000939:Epitopes; D008565:Membrane Proteins; D015800:Protozoan Proteins; C534665:RIFIN protein, Plasmodium falciparum