Epitopes of anti-RIFIN antibodies and characterization of rif-expressing Plasmodium falciparum parasites by RNA sequencing

• DOI: 10.1038/srep43190
• Publication Date: 2017-02-24T11:17:54Z
• Authors: Jun-Hong Ch’ng; Madle Sirel; Arash Zandian; Maria del Pilar Q...; Sherwin Chun Leun...; Kirsten Moll; Asa Tellgren-Roth; IngMarie Nilsson; Peter Nilsson; Ulrika Qundos; Mats Wahlgren
• Keywords: 0301 basic medicine; sequence analysis; Leporidae; Plasmodium falciparum; Protozoan Proteins; Antibodies, Protozoan; Antibodies; Article; immunology; Epitopes; 03 medical and health sciences; 616; gene expression profiling; Animals; membrane protein; animal; genetics; protozoon antibody; epitope; 0303 health sciences; RIFIN protein; protozoal protein; Sequence Analysis, RNA; Gene Expression Profiling; Goats; goat; Membrane Proteins; 3. Good health; epitope mapping; Protozoan; RNA; Rabbits; Epitope Mapping

AbstractVariable 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.