title: Evaluation of Naturally Acquired Antibody Responses to Two Variant Forms of Plasmodium vivax Apical Membrane Antigen-1 in Individuals Living in Areas of Low and Unstable Malaria Transmission of Iran.
abstract: BACKGROUND
  Acquired antibody responses following natural infection provide valuable information for selection of candidate antigens for malaria vaccines. Apical membrane antigen-1 of Plasmodium vivax (PvAMA-1) has potential as a component of a subunit vaccine for vivax malaria. In addition, genetic diversity in this antigen is responsible for challenges in the development of an effective PvAMA-1 based vaccine. Therefore, the main aim of this study was to determine whether allelic polymorphisms in pvama-1 influence the recognition of naturally occurring antibodies. Also, the profile of IgG isotypes to two sequence types of PvAMA-1 antigen was evaluated among subjects exposed to P. vivax in areas of low and unstable transmission.
  
  
  METHODS
  For this purpose, the two variant forms of PvAMA-1 (PvAMA-1A and B) were expressed in Escherichia coli M15-pQE30 system using genomic DNA from Iranian individuals with patent P. vivax infection. Anti-AMA-1 response and isotype composition to two variant forms were measured in target P. vivax-infected individuals (n = 110, 2 to 65 years old) using Enzyme-linked immunosorbent assay.
  
  
  RESULTS
  The results showed that 65.5% of the studied individuals had positive IgG responses to two PvAMA-1 variants, and the prevalence of responders did not differ significantly (P = 0.32). Also, a marked isotype switching to cytophilic (IgG1 /IgG3) antibodies was evident with increasing age, and adults responded more frequently to these antigens than did younger children.
  
  
  CONCLUSIONS
  The presence of mature, protective isotype antibodies and equal immune responses to two genetically distinct variant forms of antigens in individuals from low transmission areas implicates that one of these forms could be used in a universal blood-stage vaccine based on PvAMA-1 antigen.
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Salavatifar
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Sedigheh
authors.initials: S
authors.lastname: Zakeri
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Akram
authors.initials: A
authors.lastname: Abouie Mehrizi
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Sedigheh
authors.initials: S
authors.lastname: Mirkhazemi
authors.affiliation: Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
authors.forename: Navid
authors.initials: N
authors.lastname: Dinparast Djadid
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000913:Antibodies, Protozoan / Q000097:blood / Q000235:genetics / Q000276:immunology*; D000953:Antigens, Protozoan / Q000235:genetics* / Q000276:immunology; D015415:Biomarkers / Q000097:blood; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006239:Haplotypes; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood / Q000276:immunology*; D007492:Iran; D016780:Malaria, Vivax / Q000097:blood / Q000276:immunology* / Q000635:transmission; D008297:Male; D008565:Membrane Proteins / Q000235:genetics* / Q000276:immunology; D008875:Middle Aged; D010966:Plasmodium vivax / Q000235:genetics / Q000276:immunology*; D020641:Polymorphism, Single Nucleotide; D015800:Protozoan Proteins / Q000235:genetics* / Q000276:immunology; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D015415:Biomarkers; D007074:Immunoglobulin G; D008565:Membrane Proteins; D015800:Protozoan Proteins; C090077:apical membrane antigen I, Plasmodium