title: Characterizing PvARP, a novel Plasmodium vivax antigen.
abstract: BACKGROUND
  Plasmodium vivax continues to be the most widely distributed malarial parasite species in tropical and sub-tropical areas, causing high morbidity indices around the world. Better understanding of the proteins used by the parasite during the invasion of red blood cells is required to obtain an effective vaccine against this disease. This study describes characterizing the P. vivax asparagine-rich protein (PvARP) and examines its antigenicity in natural infection.
  
  
  METHODS
  The target gene in the study was selected according to a previous in silico analysis using profile hidden Markov models which identified P. vivax proteins that play a possible role in invasion. Transcription of the arp gene in the P. vivax VCG-1 strain was here evaluated by RT-PCR. Specific human antibodies against PvARP were used to confirm protein expression by Western blot as well as its subcellular localization by immunofluorescence. Recognition of recombinant PvARP by sera from P. vivax-infected individuals was evaluated by ELISA.
  
  
  RESULTS
  VCG-1 strain PvARP is a 281-residue-long molecule, which is encoded by a single exon and has an N-terminal secretion signal, as well as a tandem repeat region. This protein is expressed in mature schizonts and is located on the surface of merozoites, having an apparent accumulation towards their apical pole. Sera from P. vivax-infected patients recognized the recombinant, thereby suggesting that this protein is targeted by the immune response during infection.
  
  
  CONCLUSIONS
  This study showed the characterization of PvARP and its antigenicity. Further assays orientated towards evaluating this antigen's functional importance during parasite invasion are being carried out.
authors.affiliation: Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50 No, 26-20, Bogotá, Colombia. mapatarr.fidic@gmail.com
authors.forename: Darwin A
authors.initials: DA
authors.lastname: Moreno-Pérez
authors.forename: Ambar
authors.initials: A
authors.lastname: Saldarriaga
authors.forename: Manuel A
authors.initials: MA
authors.lastname: Patarroyo
mesh_terms: D000913:Antibodies, Protozoan / Q000097:blood; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology*; D015153:Blotting, Western; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D004797:Enzyme-Linked Immunosorbent Assay; D005455:Fluorescent Antibody Technique; D020869:Gene Expression Profiling; D006801:Humans; D008969:Molecular Sequence Data; D010966:Plasmodium vivax / Q000235:genetics* / Q000276:immunology*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D014158:Transcription, Genetic
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D016054:DNA, Protozoan