title: Malaria vaccine candidate antigen targeting the pre-erythrocytic stage of Plasmodium falciparum produced at high level in plants.
abstract: Plants have emerged as low-cost production platforms suitable for vaccines targeting poverty-related diseases. Besides functional efficacy, the stability, yield, and purification process determine the production costs of a vaccine and thereby the feasibility of plant-based production. We describe high-level plant production and functional characterization of a malaria vaccine candidate targeting the pre-erythrocytic stage of Plasmodium falciparum. CCT, a fusion protein composed of three sporozoite antigens (P. falciparum cell traversal protein for ookinetes and sporozoites [PfCelTOS], P. falciparum circumsporozoite protein [PfCSP], and P. falciparum thrombospondin-related adhesive protein [PfTRAP]), was transiently expressed by agroinfiltration in Nicotiana benthamiana leaves, accumulated to levels up to 2 mg/g fresh leaf weight (FLW), was thermostable up to 80°C and could be purified to >95% using a simple two-step procedure. Reactivity of sera from malaria semi-immune donors indicated the immunogenic conformation of the purified fusion protein consisting of PfCelTOS, PfCSP_TSR, PfTRAP_TSR domains (CCT) protein. Total IgG from the CCT-specific mouse immune sera specifically recognized P. falciparum sporozoites in immunofluorescence assays and induced up to 35% inhibition in hepatocyte invasion assays. Featuring domains from three promising sporozoite antigens with different roles (attachment and cell traversal) in the hepatocyte invasion process, CCT has the potential to elicit broader immune responses against the pre-erythrocytic stage of P. falciparum and represents an interesting new candidate, also as a component of multi-stage, multi-subunit malaria vaccine cocktails.
authors.affiliation: Department Plant Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
authors.forename: Nadja
authors.initials: N
authors.lastname: Voepel
authors.forename: Alexander
authors.initials: A
authors.lastname: Boes
authors.forename: Güven
authors.initials: G
authors.lastname: Edgue
authors.forename: Veronique
authors.initials: V
authors.lastname: Beiss
authors.forename: Stephanie
authors.initials: S
authors.lastname: Kapelski
authors.forename: Andreas
authors.initials: A
authors.lastname: Reimann
authors.forename: Stefan
authors.initials: S
authors.lastname: Schillberg
authors.forename: Gabriele
authors.initials: G
authors.lastname: Pradel
authors.forename: Rolf
authors.initials: R
authors.lastname: Fendel
authors.forename: Matthias
authors.initials: M
authors.lastname: Scheuermayer
authors.forename: Holger
authors.initials: H
authors.lastname: Spiegel
authors.forename: Rainer
authors.initials: R
authors.lastname: Fischer
mesh_terms: D000818:Animals; D000913:Antibodies, Protozoan / Q000097:blood / Q000276:immunology; D006358:Hot Temperature; D006801:Humans; D017780:Malaria Vaccines; D016778:Malaria, Falciparum / Q000276:immunology / Q000469:parasitology; D051379:Mice; D018515:Plant Leaves / Q000378:metabolism; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism*; D010963:Plasmodium falciparum / Q000235:genetics / Q000276:immunology*; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D034101:Sporozoites / Q000276:immunology*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism*
chemical_list: D000913:Antibodies, Protozoan; D017780:Malaria Vaccines; D015800:Protozoan Proteins; D011993:Recombinant Fusion Proteins
keywords: Agroinfiltration; Host cell protein removal; Multidomain antigen; Nicotiana benthamiana; Plant molecular farming