title: Comparative analysis of IgG responses to Plasmodium falciparum MSP1p19 and PF13-DBL1α1 using ELISA and a magnetic bead-based duplex assay (MAGPIX®-Luminex) in a Senegalese meso-endemic community.
abstract: BACKGROUND
  Numerous Plasmodium falciparum antigens elicit humoral responses in humans living in endemic areas. Use of multiplex assays is a convenient approach to monitor the antibody response against multiple antigens, but to integrate multiplex assay-derived data with datasets, generated previously using ELISA, comparative studies are needed. This work compares antibody responses to two P. falciparum antigens monitored using both technologies.
  
  
  METHODS
  The IgG response against the merozoite surface protein-1 PfMSP1p19 and the PF13-DBL1α1 domain of the P. falciparum Erythrocyte Membrane Protein1, expressed by the rosette-forming parasite 3D7/PF13 (PF13), was investigated using ELISA and a MAGPIX®-Luminex duplex assay. Archived plasma samples collected before the rainy season from 217 villagers living in Ndiop, a Senegalese meso-endemic setting, were studied. ROC analysis was used to define the optimal antibody measure readout. Association of antibody levels with protection against clinical malaria was analysed using Poisson regression in a retrospective study from active case detection records performed during the 5.5-month transmission season that followed blood sampling.
  
  
  RESULTS
  There was a strong positive correlation (P<10(-3)) between ELISA and MAGPIX®-Luminex-MFI (median fluorescence intensity) values for antibody to PfMSP1p19 (rho=0.78) and PF13-DBL1α1 (rho=0.89), with a similar degree of concordance in all age groups. Antibody levels to both antigens were high but displayed a different age-associated pattern. Independent age-adjusted Poisson regression analysis showed a significant association with protection only for IgG responses to MSP1p19 (P<0.01 RR=0.71 [0.53-0.93]) measured by ELISA.
  
  
  CONCLUSIONS
  The individual ELISA and duplex-MAGPIX assays provide a concordant evaluation of age-associated antibody responses to MSP1p19 and PF13-DBL1α1, irrespective of the formulation of antibody levels (values, ratios or ROC-adjusted figures) but do diverge with regard to the association of antibody levels with clinical protection in age-adjusted models. This may reflect incomplete overlap of the epitopes presented in the two formats. Further development for multiplex assessment of antibody responses to a larger panel of antigens with the robust and cost effective MAGPIX®-Luminex technology is warranted.
authors.affiliation: Institut Pasteur de Dakar, Unité d'Immunologie, Dakar, Sénégal. perraut@pasteur.sn.
authors.forename: Ronald
authors.initials: R
authors.lastname: Perraut
authors.forename: Vincent
authors.initials: V
authors.lastname: Richard
authors.forename: Marie-Louise
authors.initials: ML
authors.lastname: Varela
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Trape
authors.forename: Micheline
authors.initials: M
authors.lastname: Guillotte
authors.forename: Adama
authors.initials: A
authors.lastname: Tall
authors.forename: Aissatou
authors.initials: A
authors.lastname: Toure
authors.forename: Cheikh
authors.initials: C
authors.lastname: Sokhna
authors.forename: Inès
authors.initials: I
authors.lastname: Vigan-Womas
authors.forename: Odile
authors.initials: O
authors.lastname: Mercereau-Puijalon
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000913:Antibodies, Protozoan / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D007231:Infant, Newborn; D016778:Malaria, Falciparum / Q000453:epidemiology / Q000276:immunology*; D008297:Male; D020066:Merozoite Surface Protein 1 / Q000276:immunology*; D008875:Middle Aged; D010963:Plasmodium falciparum / Q000276:immunology*; D015995:Prevalence; D015800:Protozoan Proteins / Q000276:immunology*; D012189:Retrospective Studies; D012675:Senegal / Q000453:epidemiology; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D007074:Immunoglobulin G; D020066:Merozoite Surface Protein 1; D015800:Protozoan Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum