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Ivanochko D, Fabra-García A, Teelen K, van de Vegte-Bolmer M, van Gemert GJ, Newton J, Semesi A, de Bruijni M, Bolscher J, Ramjith J, Szabat M, Vogt S, Kraft L, Duncan S, Lee SM, Kamya MR, Feeney ME, Jagannathan P, Greenhouse B, Sauerwein RW, Richter King C, MacGill RS, Bousema T, Jore MM, Julien JP. Potent transmission-blocking monoclonal antibodies from naturally exposed individuals target a conserved epitope on Plasmodium falciparum Pfs230. Immunity 2023; 56:420-432.e7. [PMID: 36792575 PMCID: PMC9942874 DOI: 10.1016/j.immuni.2023.01.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2022] [Revised: 11/04/2022] [Accepted: 01/12/2023] [Indexed: 02/16/2023]
Abstract
Pfs230 is essential for Plasmodium falciparum transmission to mosquitoes and is the protein targeted by the most advanced malaria-transmission-blocking vaccine candidate. Prior understanding of functional epitopes on Pfs230 is based on two monoclonal antibodies (mAbs) with moderate transmission-reducing activity (TRA), elicited from subunit immunization. Here, we screened the B cell repertoire of two naturally exposed individuals possessing serum TRA and identified five potent mAbs from sixteen Pfs230 domain-1-specific mAbs. Structures of three potent and three low-activity antibodies bound to Pfs230 domain 1 revealed four distinct epitopes. Highly potent mAbs from natural infection recognized a common conformational epitope that is highly conserved across P. falciparum field isolates, while antibodies with negligible TRA derived from natural infection or immunization recognized three distinct sites. Our study provides molecular blueprints describing P. falciparum TRA, informed by contrasting potent and non-functional epitopes elicited by natural exposure and vaccination.
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Affiliation(s)
- Danton Ivanochko
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | - Karina Teelen
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Jocelyn Newton
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | - Anthony Semesi
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada
| | | | | | - Jordache Ramjith
- Radboud Institute for Health Sciences, Department for Health Evidence, Biostatistics Section, Radboudumc, Nijmegen, the Netherlands
| | | | | | - Lucas Kraft
- AbCellera Biologics Inc., Vancouver, BC, Canada
| | | | - Shwu-Maan Lee
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | - Moses R Kamya
- Infectious Disease Research Collaboration, Kampala, Uganda
| | - Margaret E Feeney
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA; Department of Pediatrics, University of California, San Francisco, San Francisco, CA, USA
| | - Prasanna Jagannathan
- Department of Microbiology and Immunology, Stanford University, Stanford, CA, USA
| | - Bryan Greenhouse
- Department of Medicine, University of California, San Francisco, San Francisco, CA, USA
| | | | - C Richter King
- PATH's Malaria Vaccine Initiative, Washington, DC 20001, USA
| | | | - Teun Bousema
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Matthijs M Jore
- Department of Medical Microbiology, Radboudumc, Nijmegen, the Netherlands.
| | - Jean-Philippe Julien
- Program in Molecular Medicine, the Hospital for Sick Children Research Institute, Toronto, ON, Canada; Departments of Biochemistry and Immunology, University of Toronto, Toronto, ON, Canada.
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Duffy PE. The Virtues and Vices of Pfs230: From Vaccine Concept to Vaccine Candidate. Am J Trop Med Hyg 2022; 107:tpmd211337. [PMID: 35895391 DOI: 10.4269/ajtmh.21-1337] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Accepted: 02/23/2022] [Indexed: 02/18/2024] Open
Abstract
Among the Plasmodium falciparum surface antigens reported by Richard Carter and his colleagues decades ago, Pfs230 is currently the target of the most advanced candidate for a malaria transmission-blocking vaccine. First identified by its orthologue in the avian malaria parasite Plasmodium gallinaceum, the large cysteine-rich 14-domain Pfs230 antigen is displayed on the surface of gametes that emerge in the mosquito midgut. Gametes lacking Pfs230 cannot bind to red blood cells nor develop further into oocysts. Human antibodies against Pfs230 lyse gametes in the presence of complement, which largely explains serum transmission-blocking activity in Pfs230 antisera. A protein-protein conjugate vaccine that incorporates the first domain of the Pfs230 antigen induced greater serum transmission-reducing activity versus a similarly manufactured Pfs25 vaccine in U.S. trials, and is currently in phase II field trials in Mali.
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Lyons FMT, Gabriela M, Tham WH, Dietrich MH. Plasmodium 6-Cysteine Proteins: Functional Diversity, Transmission-Blocking Antibodies and Structural Scaffolds. Front Cell Infect Microbiol 2022; 12:945924. [PMID: 35899047 PMCID: PMC9309271 DOI: 10.3389/fcimb.2022.945924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Accepted: 06/22/2022] [Indexed: 11/30/2022] Open
Abstract
The 6-cysteine protein family is one of the most abundant surface antigens that are expressed throughout the Plasmodium falciparum life cycle. Many members of the 6-cysteine family have critical roles in parasite development across the life cycle in parasite transmission, evasion of the host immune response and host cell invasion. The common feature of the family is the 6-cysteine domain, also referred to as s48/45 domain, which is conserved across Aconoidasida. This review summarizes the current approaches for recombinant expression for 6-cysteine proteins, monoclonal antibodies against 6-cysteine proteins that block transmission and the growing collection of crystal structures that provide insights into the functional domains of this protein family.
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Affiliation(s)
- Frankie M. T. Lyons
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Mikha Gabriela
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Wai-Hong Tham
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
| | - Melanie H. Dietrich
- The Walter and Eliza Hall Institute of Medical Research, Infectious Diseases and Immune Defence Division, Parkville, VIC, Australia
- Department of Medical Biology, The University of Melbourne, Melbourne, VIC, Australia
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Elucidating functional epitopes within the N-terminal region of malaria transmission blocking vaccine antigen Pfs230. NPJ Vaccines 2022; 7:4. [PMID: 35027567 PMCID: PMC8758780 DOI: 10.1038/s41541-021-00423-3] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 11/30/2021] [Indexed: 11/24/2022] Open
Abstract
Pfs230 is a leading malaria transmission blocking vaccine (TBV) candidate. Comprising 3135 amino acids (aa), the large size of Pfs230 necessitates the use of sub-fragments as vaccine immunogens. Therefore, determination of which regions induce functional antibody responses is essential. We previously reported that of 27 sub-fragments spanning the entire molecule, only five induced functional antibodies. A “functional” antibody is defined herein as one that inhibits Plasmodium falciparum parasite development in mosquitoes in a standard membrane-feeding assay (SMFA). These five sub-fragments were found within the aa 443–1274 range, and all contained aa 543–730. Here, we further pinpoint the location of epitopes within Pfs230 that are recognized by functional antibodies using antibody depletion and enrichment techniques. Functional epitopes were not found within the aa 918–1274 region. Within aa 443–917, further analysis showed the existence of functional epitopes not only within the aa 543–730 region but also outside of it. Affinity-purified antibodies using a synthetic peptide matching aa 543–588 showed activity in the SMFA. Immunization with a synthetic peptide comprising this segment, formulated either as a carrier-protein conjugate vaccine or with a liposomal vaccine adjuvant system, induced antibodies in mice that were functional in the SMFA. These findings provide key insights for Pfs230-based vaccine design and establish the feasibility for the use of synthetic peptide antigens for a malaria TBV.
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Pirahmadi S, Afzali S, Zargar M, Zakeri S, Mehrizi AA. How can we develop an effective subunit vaccine to achieve successful malaria eradication? Microb Pathog 2021; 160:105203. [PMID: 34547408 DOI: 10.1016/j.micpath.2021.105203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Revised: 08/05/2021] [Accepted: 09/17/2021] [Indexed: 12/16/2022]
Abstract
Malaria, a mosquito-borne infection, is the most widespread parasitic disease. Despite numerous efforts to eradicate malaria, this disease is still a health concern worldwide. Owing to insecticide-resistant vectors and drug-resistant parasites, available controlling measures are insufficient to achieve a malaria-free world. Thus, there is an urgent need for new intervention tools such as efficient malaria vaccines. Subunit vaccines are the most promising malaria vaccines under development. However, one of the major drawbacks of subunit vaccines is the lack of efficient and durable immune responses including antigen-specific antibody, CD4+, and CD8+ T-cell responses, long-lived plasma cells, memory cells, and functional antibodies for parasite neutralization or inhibition of parasite invasion. These types of responses could be induced by whole organism vaccines, but eliciting these responses with subunit vaccines has been proven to be more challenging. Consequently, subunit vaccines require several policies to overcome these challenges. In this review, we address common approaches that can improve the efficacy of subunit vaccines against malaria.
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Affiliation(s)
- Sakineh Pirahmadi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - Shima Afzali
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - Mostafa Zargar
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran
| | - Sedigheh Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
| | - Akram Abouie Mehrizi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran.
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Qiu Y, Zhao Y, Liu F, Ye B, Zhao Z, Thongpoon S, Roobsoong W, Sattabongkot J, Cui L, Fan Q, Cao Y. Evaluation of Plasmodium vivax HAP2 as a transmission-blocking vaccine candidate. Vaccine 2020; 38:2841-2848. [PMID: 32093983 DOI: 10.1016/j.vaccine.2020.02.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/31/2020] [Accepted: 02/05/2020] [Indexed: 12/23/2022]
Abstract
Transmission-blocking vaccine (TBV) is a promising strategy to interfere with the transmission of malaria. To date, only limited TBV candidate antigens have been identified for Plasmodium vivax. HAP2 is a gamete membrane fusion protein, with homology to the class II viral fusion proteins. Herein we reported the characterization of the PvHAP2 for its potential as a TBV candidate for P. vivax. The HAP2/GCS1 domain of PvHAP2 was expressed in the baculovirus expression system and the recombinant protein was used to raise antibodies in rabbits. Indirect immunofluorescence assays showed that anti-PvHAP2 antibodies reacted only with the male gametocytes on blood smears. Direct membrane feeding assays were conducted using four field P. vivax isolates in Anopheles dirus. At a mean infection intensity of 72.4, 70.7, 51.3, and 15.6 oocysts/midgut with the control antibodies, anti-PvHAP2 antibodies significantly reduced the midgut oocyst intensity by 40.3, 44.4, 61.9, and 89.7%. Whereas the anti-PvHAP2 antibodies were not effective in reducing the infection prevalence at higher parasite exposure (51.3-72.4 oocysts/midgut in the control group), the anti-PvHAP2 antibodies reduced infection prevalence by 50% at a low challenge (15.6 oocysts/midgut). Multiple sequence alignment showed 100% identity among these Thai P. vivax isolates, suggesting that polymorphism may not be an impediment for the utilization of PvHAP2 as a TBV antigen. In conclusion, our results suggest that PvHAP2 could serve as a TBV candidate for P. vivax, and further optimization and evaluation are warranted.
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Affiliation(s)
- Yue Qiu
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110122, China
| | - Yan Zhao
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110122, China
| | - Fei Liu
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110122, China
| | - Bo Ye
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Zhenjun Zhao
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Sataporn Thongpoon
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Wanlapa Roobsoong
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Thailand
| | - Liwang Cui
- Department of Internal Medicine, Morsani College of Medicine, University of South Florida, 3720 Spectrum Boulevard, Suite 304, Tampa, FL 33612, USA
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Yaming Cao
- Department of Immunology, College of Basic Medical Science, China Medical University, Shenyang, Liaoning 110122, China.
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Lee SM, Hickey JM, Miura K, Joshi SB, Volkin DB, King CR, Plieskatt JL. A C-terminal Pfs48/45 malaria transmission-blocking vaccine candidate produced in the baculovirus expression system. Sci Rep 2020; 10:395. [PMID: 31942034 PMCID: PMC6962329 DOI: 10.1038/s41598-019-57384-w] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2019] [Accepted: 12/30/2019] [Indexed: 11/09/2022] Open
Abstract
The Plasmodium falciparum gametocyte surface protein, Pfs48/45, is a potential target for malaria transmission-blocking vaccines. However, due to its size and complexity, expression of the full-length protein has been difficult, leading to focus on the C-terminal six cysteine domain (6C) with the use of fusion proteins to facilitate expression and folding. In this study, we utilized the baculovirus system to evaluate the expression of three Pfs48/45 proteins including the full-length protein, the 6C domain fragment and the 6C domain mutant to prevent glycosylation. Expression of the recombinant Pfs48/45 proteins was conducted in super Sf9 cells combined with the use of tunicamycin to prevent N-glycosylation. The proteins were then evaluated as immunogens in mice to demonstrate the induction of functionally active polyclonal antibody responses as measured in the standard membrane feeding assay (SMFA). Only the 6C protein was found to exhibit significant transmission-reducing activity. Further characterization of the biologically active 6C protein demonstrated it was homogeneous in terms of size, charge, conformation, absence of glycosylation, and containing proper disulfide bond pairings. This study presents an alternative expression system, without the need of a fusion protein partner, for the Pfs48/45 6C protein fragment including further evaluation as a potential transmission-blocking vaccine candidate.
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Affiliation(s)
- Shwu-Maan Lee
- PATH's Malaria Vaccine Initiative (MVI), 455 Massachusetts Avenue NW, Suite 1000, Washington, DC, 20001-2621, USA.
| | - John M Hickey
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center, University of Kansas, Lawrence, KS, 66047, USA
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, 20852, USA
| | - Sangeeta B Joshi
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center, University of Kansas, Lawrence, KS, 66047, USA
| | - David B Volkin
- Department of Pharmaceutical Chemistry, Vaccine Analytics and Formulation Center, University of Kansas, Lawrence, KS, 66047, USA
| | - C Richter King
- PATH's Malaria Vaccine Initiative (MVI), 455 Massachusetts Avenue NW, Suite 1000, Washington, DC, 20001-2621, USA
| | - Jordan L Plieskatt
- PATH's Malaria Vaccine Initiative (MVI), 455 Massachusetts Avenue NW, Suite 1000, Washington, DC, 20001-2621, USA
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de Jong RM, Tebeje SK, Meerstein‐Kessel L, Tadesse FG, Jore MM, Stone W, Bousema T. Immunity against sexual stage Plasmodium falciparum and Plasmodium vivax parasites. Immunol Rev 2020; 293:190-215. [PMID: 31840844 PMCID: PMC6973022 DOI: 10.1111/imr.12828] [Citation(s) in RCA: 57] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2019] [Revised: 10/30/2019] [Accepted: 11/14/2019] [Indexed: 12/25/2022]
Abstract
The efficient spread of malaria from infected humans to mosquitoes is a major challenge for malaria elimination initiatives. Gametocytes are the only Plasmodium life stage infectious to mosquitoes. Here, we summarize evidence for naturally acquired anti-gametocyte immunity and the current state of transmission blocking vaccines (TBV). Although gametocytes are intra-erythrocytic when present in infected humans, developing Plasmodium falciparum gametocytes may express proteins on the surface of red blood cells that elicit immune responses in naturally exposed individuals. This immune response may reduce the burden of circulating gametocytes. For both P. falciparum and Plasmodium vivax, there is a solid evidence that antibodies against antigens present on the gametocyte surface, when co-ingested with gametocytes, can influence transmission to mosquitoes. Transmission reducing immunity, reducing the burden of infection in mosquitoes, is a well-acknowledged but poorly quantified phenomenon that forms the basis for the development of TBV. Transmission enhancing immunity, increasing the likelihood or intensity of transmission to mosquitoes, is more speculative in nature but is convincingly demonstrated for P. vivax. With the increased interest in malaria elimination, TBV and monoclonal antibodies have moved to the center stage of malaria vaccine development. Methodologies to prioritize and evaluate products are urgently needed.
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MESH Headings
- Antibodies, Blocking/immunology
- Antibodies, Protozoan/immunology
- Host-Parasite Interactions/immunology
- Humans
- Immunity
- Immunomodulation
- Life Cycle Stages
- Malaria Vaccines/immunology
- Malaria, Falciparum/immunology
- Malaria, Falciparum/parasitology
- Malaria, Falciparum/prevention & control
- Malaria, Falciparum/transmission
- Malaria, Vivax/immunology
- Malaria, Vivax/parasitology
- Malaria, Vivax/prevention & control
- Malaria, Vivax/transmission
- Plasmodium falciparum/growth & development
- Plasmodium falciparum/immunology
- Plasmodium vivax/growth & development
- Plasmodium vivax/immunology
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Affiliation(s)
- Roos M. de Jong
- Radboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | | | - Lisette Meerstein‐Kessel
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
- Centre for Molecular and Biomolecular InformaticsRadboud Institute for Molecular Life SciencesNijmegenThe Netherlands
| | - Fitsum G. Tadesse
- Armauer Hansen Research InstituteAddis AbabaEthiopia
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Matthijs M. Jore
- Radboud Institute for Molecular Life SciencesRadboud University Medical CenterNijmegenThe Netherlands
| | - Will Stone
- Department of Immunology and InfectionLondon School of Hygiene and Tropical MedicineLondonUK
| | - Teun Bousema
- Radboud Institute for Health SciencesRadboud University Medical CenterNijmegenThe Netherlands
- Department of Immunology and InfectionLondon School of Hygiene and Tropical MedicineLondonUK
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The Pfs230 N-terminal fragment, Pfs230D1+: expression and characterization of a potential malaria transmission-blocking vaccine candidate. Malar J 2019; 18:356. [PMID: 31703583 PMCID: PMC6839146 DOI: 10.1186/s12936-019-2989-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Accepted: 10/24/2019] [Indexed: 12/31/2022] Open
Abstract
Background Control and elimination of malaria can be accelerated by transmission-blocking interventions such as vaccines. A surface antigen of Plasmodium falciparum gametocytes, Pfs230, is a leading vaccine target antigen, and has recently progressed to experimental clinical trials. To support vaccine product development, an N-terminal Pfs230 antigen was designed to increase yield, as well as to improve antigen quality, integrity, and homogeneity. Methods A scalable baculovirus expression system was used to express the Pfs230D1+ construct (aa 552–731), which was subsequently purified and analysed. Pfs230D1+ was designed to avoid glycosylation and protease digestion, thereby potentially increasing homogeneity and stability. The resulting Pfs230D1+ protein was compared to a previous iteration of the Pfs230 N-terminal domain, Pfs230C1 (aa 443–731), through physiochemical characterization and in vivo analysis. The induction of functional antibody responses was confirmed via the standard membrane feeding assay (SMFA). Results Pfs230D1+ was produced and purified to an overall yield of 23 mg/L culture supernatant, a twofold yield increase over Pfs230C1. The Pfs230D1+ protein migrated as a single band via SDS-PAGE and was detected by anti-Pfs230C1 monoclonal antibodies. Evaluation by SDS-PAGE, chromatography (size-exclusion and reversed phase) and capillary isoelectric focusing demonstrated the molecule had improved homogeneity in terms of size, conformation, and charge. Intact mass spectrometry confirmed its molecular weight and that it was free of glycosylation, a key difference to the prior Pfs230C1 protein. The correct formation of the two intramolecular disulfide bonds was initially inferred by binding of a conformation specific monoclonal antibody and directly confirmed by LC/MS and peptide mapping. When injected into mice the Pfs230D1+ protein elicited antibodies that demonstrated transmission-reducing activity, via SMFA, comparable to Pfs230C1. Conclusion By elimination of an O-glycosylation site, a potential N-glycosylation site, and two proteolytic cleavage sites, an improved N-terminal Pfs230 fragment was produced, termed D1+, which is non-glycosylated, homogeneous, and biologically active. An intact protein at higher yield than that previously observed for the Pfs230C1 fragment was achieved. The results indicate that Pfs230D1+ protein produced in the baculovirus expression system is an attractive antigen for transmission-blocking vaccine development.
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Plasmodium Genomics and Genetics: New Insights into Malaria Pathogenesis, Drug Resistance, Epidemiology, and Evolution. Clin Microbiol Rev 2019; 32:32/4/e00019-19. [PMID: 31366610 DOI: 10.1128/cmr.00019-19] [Citation(s) in RCA: 53] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Protozoan Plasmodium parasites are the causative agents of malaria, a deadly disease that continues to afflict hundreds of millions of people every year. Infections with malaria parasites can be asymptomatic, with mild or severe symptoms, or fatal, depending on many factors such as parasite virulence and host immune status. Malaria can be treated with various drugs, with artemisinin-based combination therapies (ACTs) being the first-line choice. Recent advances in genetics and genomics of malaria parasites have contributed greatly to our understanding of parasite population dynamics, transmission, drug responses, and pathogenesis. However, knowledge gaps in parasite biology and host-parasite interactions still remain. Parasites resistant to multiple antimalarial drugs have emerged, while advanced clinical trials have shown partial efficacy for one available vaccine. Here we discuss genetic and genomic studies of Plasmodium biology, host-parasite interactions, population structures, mosquito infectivity, antigenic variation, and targets for treatment and immunization. Knowledge from these studies will advance our understanding of malaria pathogenesis, epidemiology, and evolution and will support work to discover and develop new medicines and vaccines.
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