title: Antibody profiles to wheat germ cell-free system synthesized Plasmodium falciparum proteins correlate with protection from symptomatic malaria in Uganda.
abstract: The key targets of protective antibodies against Plasmodium falciparum remain largely unknown. In this study, we determined immunoreactivity to 1827 recombinant proteins derived from 1565 genes representing ∼30% of the entire P. falciparum genome, for identification of novel malaria vaccine candidates. The recombinant proteins were expressed by wheat germ cell-free system, a platform that can synthesize quality plasmodial proteins that elicit biologically active antibodies in animals. Sera were obtained from indigenous residents of a malaria endemic region in Northern Uganda who were enrolled at the start of a rainy season and prospectively monitored for symptomatic malaria episodes for a year. Immunoreactivity to sera was determined by AlphaScreen; a homogeneous high-throughput system that detects protein interactions. Our analysis revealed antibody responses to 128 proteins that significantly associated with protection from symptomatic malaria. From 128 proteins, 53 were down-selected as the most plausible targets of host protective immune response by virtue of having a predicted signal peptide and/or transmembrane domain(s), or confirmed localization on the parasite surface. The 53 proteins comprised of not only previously characterized vaccine candidates but also uncharacterized proteins. Proteins involved in erythrocyte invasion; RON4, RON2 and CLAG3.1 and pre-erythrocytic proteins; SIAP-2, TRAP and CelTOS, were recommended for prioritization for further evaluation as vaccine candidates. The findings clearly demonstrate that generation of the protein library using the wheat germ cell-free system coupled with high throughput immunoscreening with AlphaScreen offers new options for rational discovery and selection of potential malaria vaccine candidates.
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Bernard N
authors.initials: BN
authors.lastname: Kanoi
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan. Electronic address: takashima.eizo.mz@ehime-u.ac.jp.
authors.forename: Eizo
authors.initials: E
authors.lastname: Takashima
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Masayuki
authors.initials: M
authors.lastname: Morita
authors.affiliation: Population Health and Immunity Division, Walter and Eliza Hall Institute of Medical Research, Melbourne, Australia; MRC Center for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, London, United Kingdom.
authors.forename: Michael T
authors.initials: MT
authors.lastname: White
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita 565-0871, Japan.
authors.forename: Nirianne M Q
authors.initials: NM
authors.lastname: Palacpac
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Edward H
authors.initials: EH
authors.lastname: Ntege
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan.
authors.forename: Betty
authors.initials: B
authors.lastname: Balikagala
authors.affiliation: Makerere University College of Health Sciences, School of Public Health, Kampala, Uganda.
authors.forename: Adoke
authors.initials: A
authors.lastname: Yeka
authors.affiliation: Med Biotech Laboratories, Plot 4-6 Bell Close, Port Bell Road Luzira, Kampala, Uganda.
authors.forename: Thomas G
authors.initials: TG
authors.lastname: Egwang
authors.affiliation: Department of Molecular Protozoology, Research Institute for Microbial Diseases, Osaka University, Suita 565-0871, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Horii
authors.affiliation: Division of Malaria Research, Proteo-Science Center, Ehime University, Matsuyama, Ehime 790-8577, Japan. Electronic address: tsuboi.takafumi.mb@ehime-u.ac.jp.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Tsuboi
mesh_terms: D000293:Adolescent; D000913:Antibodies, Protozoan / Q000097:blood / Q000737:chemistry; D000953:Antigens, Protozoan / Q000737:chemistry / Q000276:immunology*; D002474:Cell-Free System / Q000737:chemistry / Q000378:metabolism; D002648:Child; D060467:Disease Resistance; D004912:Erythrocytes / Q000469:parasitology; D005260:Female; D018503:Genome, Protozoan / Q000276:immunology*; D005854:Germ Cells / Q000737:chemistry / Q000378:metabolism; D057166:High-Throughput Screening Assays; D006801:Humans; D007106:Immune Sera / Q000737:chemistry; D017780:Malaria Vaccines / Q000096:biosynthesis* / Q000737:chemistry; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology / Q000517:prevention & control*; D008297:Male; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000235:genetics / Q000276:immunology; D014908:Triticum / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014454:Uganda; D055815:Young Adult
chemical_list: D000913:Antibodies, Protozoan; D000953:Antigens, Protozoan; D007106:Immune Sera; D017780:Malaria Vaccines; D015800:Protozoan Proteins; D011994:Recombinant Proteins
keywords: Malaria; Naturally acquired immunity; Uganda; Vaccine