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Miura K. How to Accelerate Early Stage of Malaria Vaccine Development by Optimizing Functional Assays. Vaccines (Basel) 2024; 12:586. [PMID: 38932315 PMCID: PMC11209467 DOI: 10.3390/vaccines12060586] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2024] [Revised: 05/23/2024] [Accepted: 05/24/2024] [Indexed: 06/28/2024] Open
Abstract
While two Plasmodium falciparum circumsporozoite protein-based pre-erythrocytic vaccines (PEV), RTS,S and R21, have been approved by the WHO, no blood-stage vaccine (BSV) or transmission-blocking vaccine (TBV) has reached a phase 3 trial. One of the major obstacles that slows down malaria vaccine development is the shortage (or lack) of in vitro assays or animal models by which investigators can reasonably select the best vaccine formulation (e.g., antigen, adjuvant, or platform) and/or immunization strategy (e.g., interval of inoculation or route of immunization) before a human phase 2 trial. In the case of PEV, RTS,S and R21 have set a benchmark, and a new vaccine can be compared with (one of) the approved PEV directly in preclinical or early clinical studies. However, such an approach cannot be utilized for BSV or TBV development at this moment. The focus of this review is in vitro assays or in vivo models that can be used for P. falciparum BSV or TBV development, and I discuss important considerations during assay selection, standardization, qualification, validation, and interpretation of the assay results. Establishment of a robust assay/model with proper interpretation of the results is the one of key elements to accelerate future vaccine development.
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Affiliation(s)
- Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852, USA
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Azcárate IG, Marín-García P, Abad P, Pérez-Benavente S, Paz-Artal E, Reche PA, Fobil JN, Rubio JM, Diez A, Puyet A, Bautista JM. Plasmodium falciparum immunodominant IgG epitopes in subclinical malaria. Sci Rep 2020; 10:9398. [PMID: 32523082 PMCID: PMC7287129 DOI: 10.1038/s41598-020-66384-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2019] [Accepted: 05/18/2020] [Indexed: 01/30/2023] Open
Abstract
Incomplete non-sterile immunity to malaria is attained in endemic regions after recurrent infections by a large percentage of the adult population, who carry the malaria parasite asymptomatically. Although blood-stage Plasmodium falciparum rapidly elicits IgG responses, the target antigens of partially protective and non-protective IgG antibodies as well as the basis for the acquisition of these antibodies remain largely unknown. We performed IgG-immunomics to screen for P. falciparum antigens and to identify epitopes associated with exposure and clinical disease. Sera from malaria cases identified five prevalent antigens recognized by all analyzed patients' IgGs. Epitope mapping of them, using adult and children sera samples from an endemic malaria region in Ghana segregated into patients with positive or negative subclinical detection of P. falciparum, revealed binding specificity for two 20-mer immunodominant antigenic regions within the START-related lipid transfer protein and the protein disulfide isomerase PDI8. These 20-mer epitopes challenged with sera samples from children under 5 years old displayed specific IgG binding in those with detectable parasitemia, even at subclinical level. These results suggest that humoral response against START and PDI8 antigens may be triggered at submicroscopic parasitemia levels in children and may eventually be used to differentially diagnose subclinical malaria in children.
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Affiliation(s)
- Isabel G Azcárate
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain.,Isabel G. Azcárate, Faculty of Health Sciences, Rey Juan Carlos University, Alcorcón, 28922, Madrid, Spain
| | | | - Paloma Abad
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Susana Pérez-Benavente
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Estela Paz-Artal
- Immunodeficiency and Transplant Immunology Unit, Research Institute Hospital 12 de Octubre (Imas12), 28041, Madrid, Spain
| | - Pedro A Reche
- Faculty of Medicine, Department of Immunology, Ophthalmology and ORL, Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Julius N Fobil
- Department of Biological, Environmental & Occupational Health Sciences, School of Public Health, College of Health Sciences, University of Ghana, P.O. Box LG 13, Legon, Ghana
| | - José M Rubio
- Malaria & Emerging Parasitic Diseases Laboratory, National Centre of Microbiology. Instituto de Salud Carlos III, 28220, Majadahonda, Spain
| | - Amalia Diez
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain
| | - Antonio Puyet
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain.
| | - José M Bautista
- Department of Biochemistry and Molecular Biology and Research Institute Hospital 12 de Octubre (Imas12), Universidad Complutense de Madrid, 28040, Madrid, Spain.
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