title: Identification of optimal epitopes for Plasmodium falciparum rapid diagnostic tests that target histidine-rich proteins 2 and 3.
abstract: Rapid diagnostic tests (RDTs) represent important tools to diagnose malaria infection. To improve understanding of the variable performance of RDTs that detect the major target in Plasmodium falciparum, namely, histidine-rich protein 2 (HRP2), and to inform the design of better tests, we undertook detailed mapping of the epitopes recognized by eight HRP-specific monoclonal antibodies (MAbs). To investigate the geographic skewing of this polymorphic protein, we analyzed the distribution of these epitopes in parasites from geographically diverse areas. To identify an ideal amino acid motif for a MAb to target in HRP2 and in the related protein HRP3, we used a purpose-designed script to perform bioinformatic analysis of 448 distinct gene sequences from pfhrp2 and from 99 sequences from the closely related gene pfhrp3. The frequency and distribution of these motifs were also compared to the MAb epitopes. Heat stability testing of MAbs immobilized on nitrocellulose membranes was also performed. Results of these experiments enabled the identification of MAbs with the most desirable characteristics for inclusion in RDTs, including copy number and coverage of target epitopes, geographic skewing, heat stability, and match with the most abundant amino acid motifs identified. This study therefore informs the selection of MAbs to include in malaria RDTs as well as in the generation of improved MAbs that should improve the performance of HRP-detecting malaria RDTs.
authors.affiliation: Clinical Tropical Medicine Laboratory, Queensland Institute of Medical Research, University of Queensland, Herston, Queensland, Australia.
authors.forename: Nelson
authors.initials: N
authors.lastname: Lee
authors.forename: Michelle L
authors.initials: ML
authors.lastname: Gatton
authors.forename: Anita
authors.initials: A
authors.lastname: Pelecanos
authors.forename: Martin
authors.initials: M
authors.lastname: Bubb
authors.forename: Iveth
authors.initials: I
authors.lastname: Gonzalez
authors.forename: David
authors.initials: D
authors.lastname: Bell
authors.forename: Qin
authors.initials: Q
authors.lastname: Cheng
authors.forename: James S
authors.initials: JS
authors.lastname: McCarthy
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal / Q000737:chemistry; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D018604:Epitope Mapping; D000939:Epitopes / Q000737:chemistry / Q000276:immunology*; D006801:Humans; D016778:Malaria, Falciparum / Q000175:diagnosis* / Q000276:immunology; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000276:immunology*; D055550:Protein Stability; D015800:Protozoan Proteins / Q000737:chemistry / Q000276:immunology*; D011934:Reagent Strips; D011961:Receptors, Fc; D012680:Sensitivity and Specificity
chemical_list: D000911:Antibodies, Monoclonal; D000953:Antigens, Protozoan; D000939:Epitopes; C514457:HRP-2 antigen, Plasmodium falciparum; C045281:IgA receptor; D015800:Protozoan Proteins; D011934:Reagent Strips; D011961:Receptors, Fc