title: Bead-based immunoassay allows sub-picogram detection of histidine-rich protein 2 from Plasmodium falciparum and estimates reliability of malaria rapid diagnostic tests.
abstract: Detection of histidine-rich protein 2 (HRP2) from the malaria parasite Plasmodium falciparum provides evidence for active or recent infection, and is utilized for both diagnostic and surveillance purposes, but current laboratory immunoassays for HRP2 are hindered by low sensitivities and high costs. Here we present a new HRP2 immunoassay based on antigen capture through a bead-based system capable of detecting HRP2 at sub-picogram levels. The assay is highly specific and cost-effective, allowing fast processing and screening of large numbers of samples. We utilized the assay to assess results of HRP2-based rapid diagnostic tests (RDTs) in different P. falciparum transmission settings, generating estimates for true performance in the field. Through this method of external validation, HRP2 RDTs were found to perform well in the high-endemic areas of Mozambique and Angola with 86.4% and 73.9% of persons with HRP2 in their blood testing positive by RDTs, respectively, and false-positive rates of 4.3% and 0.5%. However, in the low-endemic setting of Haiti, only 14.5% of persons found to be HRP2 positive by the bead assay were RDT positive. Additionally, 62.5% of Haitians showing a positive RDT test had no detectable HRP2 by the bead assay, likely indicating that these were false positive tests. In addition to RDT validation, HRP2 biomass was assessed for the populations in these different settings, and may provide an additional metric by which to estimate P. falciparum transmission intensity and measure the impact of interventions.
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Eric
authors.initials: E
authors.lastname: Rogier
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Mateusz
authors.initials: M
authors.lastname: Plucinski
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Naomi
authors.initials: N
authors.lastname: Lucchi
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Kimberly
authors.initials: K
authors.lastname: Mace
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Michelle
authors.initials: M
authors.lastname: Chang
authors.affiliation: Programme National de Contrôle de la Malaria, Ministère de la Santé Publique et de la Population (MSPP), Port-au-Prince, Haiti.
authors.forename: Jean Frantz
authors.initials: JF
authors.lastname: Lemoine
authors.affiliation: National Malaria Control Program, Maputo, Mozambique.
authors.forename: Baltazar
authors.initials: B
authors.lastname: Candrinho
authors.affiliation: Clinton Health Access Initiative, Boston, Massachusetts, United States of America.
authors.forename: James
authors.initials: J
authors.lastname: Colborn
authors.affiliation: National Malaria Control Program, Luanda, Angola.
authors.forename: Rafael
authors.initials: R
authors.lastname: Dimbu
authors.affiliation: National Malaria Control Program, Luanda, Angola.
authors.forename: Filomeno
authors.initials: F
authors.lastname: Fortes
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: Venkatachalam
authors.initials: V
authors.lastname: Udhayakumar
authors.affiliation: The Centers for Disease Control and Prevention, Center for Global Health, Division of Parasitic Diseases and Malaria, Malaria Branch, Atlanta, GA, United States of America.
authors.forename: John
authors.initials: J
authors.lastname: Barnwell
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000595:Amino Acid Sequence; D000810:Angola / Q000453:epidemiology; D000953:Antigens, Protozoan / Q000032:analysis*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D003955:Diagnostic Tests, Routine / Q000379:methods; D019353:Endemic Diseases; D006205:Haiti / Q000453:epidemiology; D006306:Health Surveys / Q000379:methods / Q000706:statistics & numerical data; D006790:Host-Parasite Interactions; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D007223:Infant; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000453:epidemiology / Q000469:parasitology; D008875:Middle Aged; D009073:Mozambique / Q000453:epidemiology; D010963:Plasmodium falciparum / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D015800:Protozoan Proteins / Q000032:analysis* / Q000235:genetics; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D055815:Young Adult
chemical_list: D000953:Antigens, Protozoan; C514457:HRP-2 antigen, Plasmodium falciparum; D015800:Protozoan Proteins