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Cummings JF, Polhemus ME, Kester KE, Ockenhouse CF, Gasser RA, Coyne P, Wortmann G, Nielsen RK, Schaecher K, Holland CA, Krzych U, Tornieporth N, Soisson LA, Angov E, Heppner DG. A phase IIa, randomized, double-blind, safety, immunogenicity and efficacy trial of Plasmodium falciparum vaccine antigens merozoite surface protein 1 and RTS,S formulated with AS02 adjuvant in healthy, malaria-naïve adults. Vaccine 2024; 42:3066-3074. [PMID: 38584058 DOI: 10.1016/j.vaccine.2024.03.072] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2023] [Revised: 03/15/2024] [Accepted: 03/25/2024] [Indexed: 04/09/2024]
Abstract
BACKGROUND To improve the efficacy of Plasmodium falciparum malaria vaccine RTS,S/AS02, we conducted a study in 2001 in healthy, malaria-naïve adults administered RTS,S/AS02 in combination with FMP1, a recombinant merozoite surface-protein-1, C-terminal 42kD fragment. METHODS A double-blind Phase I/IIa study randomized N = 60 subjects 1:1:1:1 to one of four groups, N = 15/group, to evaluate safety, immunogenicity, and efficacy of intra-deltoid half-doses of RTS,S/AS02 and FMP1/AS02 administered in the contralateral (RTS,S + FMP1-separate) or same (RTS,S + FMP1-same) sites, or FMP1/AS02 alone (FMP1-alone), or RTS,S/AS02 alone (RTS,S-alone) on a 0-, 1-, 3-month schedule. Subjects receiving three doses of vaccine and non-immunized controls (N = 11) were infected with homologous P. falciparum 3D7 sporozoites by Controlled Human Malaria Infection (CHMI). RESULTS Subjects in all vaccination groups experienced mostly mild or moderate local and general adverse events that resolved within eight days. Anti-circumsporozoite antibody levels were lower when FMP1 and RTS,S were co-administered at the same site (35.0 µg/mL: 95 % CI 20.3-63), versus separate arms (57.4 µg/mL: 95 % CI 32.3-102) or RTS,S alone (62.0 µg/mL: 95 % CI: 37.8-101.8). RTS,S-specific lymphoproliferative responses and ex vivo ELISpot CSP-specific interferon-gamma (IFN-γ) responses were indistinguishable among groups receiving RTS,S/AS02. There was no difference in antibody to FMP1 among groups receiving FMP1/AS02. After CHMI, groups immunized with a RTS,S-containing regimen had ∼ 30 % sterile protection against parasitemia, and equivalent delays in time-to-parasitemia. The FMP1/AS02 alone group showed no sterile immunity or delay in parasitemia. CONCLUSION Co-administration of RTS,S and FMP1/AS02 reduced anti-RTS,S antibody, but did not affect tolerability, cellular immunity, or efficacy in a stringent CHMI model. Absence of efficacy or delay of patency in the sporozoite challenge model in the FMP1/AS02 group did not rule out efficacy of FMP1/AS02 in an endemic population. However, a Phase IIb trial of FMP1/AS02 in children in malaria-endemic Kenya did not demonstrate efficacy against natural infection. CLINICALTRIALS gov identifier: NCT01556945.
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Affiliation(s)
- J F Cummings
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - M E Polhemus
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - K E Kester
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - C F Ockenhouse
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - R A Gasser
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - P Coyne
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - G Wortmann
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - R K Nielsen
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - K Schaecher
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - C A Holland
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | - U Krzych
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
| | | | - L A Soisson
- Malaria Vaccine Development Program, United States Agency for International Development, Washington, DC, USA
| | - E Angov
- Walter Reed Army Institute of Research, Silver Spring, MD, USA.
| | - D G Heppner
- Walter Reed Army Institute of Research, Silver Spring, MD, USA
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2
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Bhide AR, Surve DH, Jindal AB. Nanocarrier based active targeting strategies against erythrocytic stage of malaria. J Control Release 2023; 362:297-308. [PMID: 37625598 DOI: 10.1016/j.jconrel.2023.08.043] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2023] [Revised: 08/03/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
The Global Technical Strategy for Malaria 2016-2030 aims to achieve a 90% reduction in malaria cases, and strategic planning and execution are crucial for accomplishing this target. This review aims to understand the complex interaction between erythrocytic receptors and parasites and to use this knowledge to actively target the erythrocytic stage of malaria. The review provides insight into the malaria life cycle, which involves various receptors such as glycophorin A, B, C, and D (GPA/B/C/D), complement receptor 1, basigin, semaphorin 7a, Band 3/ GPA, Kx, and heparan sulfate proteoglycan for parasite cellular binding and ingress in the erythrocytic and exo-erythrocytic stages. Synthetic peptides mimicking P. falciparum receptor binding ligands, human serum albumin, chondroitin sulfate, synthetic polymers, and lipids have been utilized as ligands and decorated onto nanocarriers for specific targeting to parasite-infected erythrocytes. The need of the hour for treatment and prophylaxis against malaria is a broadened horizon that includes multiple targeting strategies against the entry, proliferation, and transmission stages of the parasite. Platform technologies with established pre-clinical safety and efficacy should be translated into clinical evaluation and formulation scale-up. Future development should be directed towards nanovaccines as proactive tools against malaria infection.
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Affiliation(s)
- Atharva R Bhide
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India
| | - Dhanashree H Surve
- Department of Chemical Engineering, University of Massachusetts, Amherst, MA 01003, United States
| | - Anil B Jindal
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Jhunjhunu, Rajasthan 333031, India.
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3
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Noordin NR, Lau YL, Cheong FW, Fong MY. Inter-Population Genetic Diversity and Clustering of Merozoite Surface Protein-1 (pkmsp-1) of Plasmodium knowlesi Isolates from Malaysia and Thailand. Trop Med Infect Dis 2023; 8:tropicalmed8050285. [PMID: 37235333 DOI: 10.3390/tropicalmed8050285] [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: 04/12/2023] [Revised: 05/12/2023] [Accepted: 05/18/2023] [Indexed: 05/28/2023] Open
Abstract
The genetic diversity of pkmsp-1 of Malaysian Plasmodium knowlesi isolates was studied recently. However, the study only included three relatively older strains from Peninsular Malaysia and focused mainly on the conserved blocks of this gene. In this study, the full-length pkmsp-1 sequence of recent P. knowlesi isolates from Peninsular Malaysia was characterized, along with Malaysian Borneo and Thailand pkmsp-1 sequences that were retrieved from GenBank. Genomic DNA of P. knowlesi was extracted from human blood specimens and the pkmsp-1 gene was PCR-amplified, cloned, and sequenced. The sequences were analysed for genetic diversity, departure from neutrality, and geographical clustering. The pkmsp-1 gene was found to be under purifying/negative selection and grouped into three clusters via a neighbour-joining tree and neighbour net inferences. Of the four polymorphic blocks in pkmsp-1, block IV, was most polymorphic, with the highest insertion-deletion (indel) sites. Two allelic families were identified in block IV, thereby highlighting the importance of this block as a promising genotyping marker for the multiplicity of infection study of P. knowlesi malaria. A single locus marker may provide an alternate, simpler method to type P. knowlesi in a population.
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Affiliation(s)
- Naqib Rafieqin Noordin
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Fei Wen Cheong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, Kuala Lumpur 50603, Malaysia
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4
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Goh XT, Lim YAL, Lee PC, Nissapatorn V, Chua KH. Diversity and natural selection of Merozoite surface Protein-1 in three species of human malaria parasites: Contribution from South-East Asian isolates. Mol Biochem Parasitol 2021; 244:111390. [PMID: 34087264 DOI: 10.1016/j.molbiopara.2021.111390] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 05/28/2021] [Accepted: 05/28/2021] [Indexed: 11/19/2022]
Abstract
The present study aimed to examine the genetic diversity of human malaria parasites (i.e., P. falciparum, P. vivax and P. knowlesi) in Malaysia and southern Thailand targeting the 19-kDa C-terminal region of Merozoite Surface Protein-1 (MSP-119). This region is essential for the recognition and invasion of erythrocytes and it is considered one of the leading candidates for asexual blood stage vaccines. However, the genetic data of MSP-119 among human malaria parasites in Malaysia is limited and there is also a need to update the current sequence diversity of this gene region among the Thailand isolates. In this study, genomic DNA was extracted from 384 microscopy-positive blood samples collected from patients who attended the hospitals or clinics in Malaysia and malaria clinics in Thailand from the year 2008 to 2016. The MSP-119 was amplified using PCR followed by bidirectional sequencing. DNA sequences identified in the present study were subjected to Median-joining network analysis with sequences of MSP-119 obtained from GenBank. DNA sequence analysis revealed that PfMSP-119 of Malaysian and Thailand isolates was not genetically conserved as high number of haplotypes were detected and positive selection was prevalent in PfMSP-119, hence questioning its suitability to be used as a vaccine candidate. A novel haplotype (Q/TNG/L) was also detected in Thailand P. falciparum isolate. In contrast, PvMSP-119 was highly conserved, however for the first time, a non-synonymous substitution (A1657S) was reported among Malaysian isolates. As for PkMSP-119, the presence of purifying selection and low nucleotide diversity indicated that it might be a potential vaccine target for P. knowlesi.
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Affiliation(s)
- Xiang Ting Goh
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Yvonne A L Lim
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
| | - Ping Chin Lee
- School of Science and Technology, University Malaysia Sabah, Kota Kinabalu, Sabah, Malaysia
| | - Veeranoot Nissapatorn
- Research Excellence Center for Innovation and Health Products (RECIHP) and School of Allied Health Sciences, Walailak University, Nakhon Si Thammarat, Thailand
| | - Kek Heng Chua
- Department of Biomedical Science, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia.
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5
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Schneider CG, Taylor JA, Sibilo MQ, Miura K, Mallory KL, Mann C, Karch C, Beck Z, Matyas GR, Long CA, Bergmann-Leitner E, Burkhard P, Angov E. Orientation of Antigen Display on Self-Assembling Protein Nanoparticles Influences Immunogenicity. Vaccines (Basel) 2021; 9:vaccines9020103. [PMID: 33572803 PMCID: PMC7911071 DOI: 10.3390/vaccines9020103] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 01/22/2021] [Accepted: 01/26/2021] [Indexed: 11/16/2022] Open
Abstract
Self-assembling protein nanoparticles (SAPN) serve as a repetitive antigen delivery platform with high-density epitope display; however, antigen characteristics such as size and epitope presentation can influence the immunogenicity of the assembled particle and are aspects to consider for a rationally designed effective vaccine. Here, we characterize the folding and immunogenicity of heterogeneous antigen display by integrating (a) dual-stage antigen SAPN presenting the P. falciparum (Pf) merozoite surface protein 1 subunit, PfMSP119, and Pf cell-traversal protein for ookinetes and sporozoites, PfCelTOS, in addition to (b) a homogenous antigen SAPN displaying two copies of PfCelTOS. Mice and rabbits were utilized to evaluate antigen-specific humoral and cellular induction as well as functional antibodies via growth inhibition of the blood-stage parasite. We demonstrate that antigen orientation and folding influence the elicited immune response, and when appropriately designed, SAPN can serve as an adaptable platform for an effective multi-antigen display.
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Affiliation(s)
- Cosette G. Schneider
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA
| | - Justin A. Taylor
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Oak Ridge Institute for Science and Education, Oak Ridge, TN 37831, USA
| | - Michael Q. Sibilo
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Parsons Corporation, Centreville, VA 20120, USA
| | - Kazutoyo Miura
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20892, USA; (K.M.); (C.A.L.)
| | - Katherine L. Mallory
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Parsons Corporation, Centreville, VA 20120, USA
| | - Christopher Mann
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Parsons Corporation, Centreville, VA 20120, USA
| | - Christopher Karch
- Laboratory of Antigen and Adjuvants, US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.K.); (Z.B.); (G.R.M.)
- Henry Jackson Foundation, Bethesda, MD 20817, USA
| | - Zoltan Beck
- Laboratory of Antigen and Adjuvants, US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.K.); (Z.B.); (G.R.M.)
- Henry Jackson Foundation, Bethesda, MD 20817, USA
| | - Gary R. Matyas
- Laboratory of Antigen and Adjuvants, US Military HIV Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.K.); (Z.B.); (G.R.M.)
| | - Carole A. Long
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, Rockville, MD 20892, USA; (K.M.); (C.A.L.)
| | - Elke Bergmann-Leitner
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
| | | | - Evelina Angov
- Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (C.G.S.); (J.A.T.); (M.Q.S.); (K.L.M.); (C.M.); (E.B.-L.)
- Correspondence: ; Tel.: +1-301-319-9614
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6
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Leitner WW, Haraway M, Pierson T, Bergmann-Leitner ES. Role of Opsonophagocytosis in Immune Protection against Malaria. Vaccines (Basel) 2020; 8:E264. [PMID: 32486320 PMCID: PMC7350021 DOI: 10.3390/vaccines8020264] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 05/25/2020] [Accepted: 05/26/2020] [Indexed: 12/15/2022] Open
Abstract
The quest for immune correlates of protection continues to slow vaccine development. To date, only vaccine-induced antibodies have been confirmed as direct immune correlates of protection against a plethora of pathogens. Vaccine immunologists, however, have learned through extensive characterizations of humoral responses that the quantitative assessment of antibody responses alone often fails to correlate with protective immunity or vaccine efficacy. Despite these limitations, the simple measurement of post-vaccination antibody titers remains the most widely used approaches for vaccine evaluation. Developing and performing functional assays to assess the biological activity of pathogen-specific responses continues to gain momentum; integrating serological assessments with functional data will ultimately result in the identification of mechanisms that contribute to protective immunity and will guide vaccine development. One of these functional readouts is phagocytosis of antigenic material tagged by immune molecules such as antibodies and/or complement components. This review summarizes our current understanding of how phagocytosis contributes to immune defense against pathogens, the pathways involved, and defense mechanisms that pathogens have evolved to deal with the threat of phagocytic removal and destruction of pathogens.
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Affiliation(s)
- Wolfgang W. Leitner
- Basic Immunology Branch, Division of Allergy, Immunology, and Transplantation/National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20852, USA;
| | - Megan Haraway
- Immunology Core/Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (M.H.); (T.P.)
| | - Tony Pierson
- Immunology Core/Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (M.H.); (T.P.)
| | - Elke S. Bergmann-Leitner
- Immunology Core/Malaria Biologics Branch, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA; (M.H.); (T.P.)
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7
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Amlabu E, Ilani P, Opoku G, Nyarko PB, Quansah E, Thiam LG, Anim M, Ayivor-Djanie R, Akuh OA, Mensah-Brown H, Rayner JC, Awandare GA. Molecular Characterization and Immuno-Reactivity Patterns of a Novel Plasmodium falciparum Armadillo-Type Repeat Protein, PfATRP. Front Cell Infect Microbiol 2020; 10:114. [PMID: 32266165 PMCID: PMC7100384 DOI: 10.3389/fcimb.2020.00114] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 03/02/2020] [Indexed: 01/30/2023] Open
Abstract
Nearly half of the genes in the Plasmodium falciparum genome have not yet been functionally investigated. We used homology-based structural modeling to identify multiple copies of Armadillo repeats within one uncharacterized gene expressed during the intraerythrocytic stages, PF3D7_0410600, subsequently referred to as P. falciparum Armadillo-Type Repeat Protein (PfATRP). Soluble recombinant PfATRP was expressed in a bacterial expression system, purified to apparent homogeneity and the identity of the recombinant PfATRP was confirmed by mass spectrometry. Affinity-purified α-PfATRP rabbit antibodies specifically recognized the recombinant protein. Immunofluorescence assays revealed that α-PfATRP rabbit antibodies reacted with P. falciparum schizonts. Anti-PfATRP antibody exhibited peripheral staining patterns around the merozoites. Given the localization of PfATRP in merozoites, we tested for an egress phenotype during schizont arrest assays and demonstrated that native PfATRP is inaccessible on the surface of merozoites in intact schizonts. Dual immunofluorescence assays with markers for the inner membrane complex (IMC) and microtubules suggest partial colocalization in both asexual and sexual stage parasites. Using the soluble recombinant PfATRP in a screen of plasma samples revealed that malaria-infected children have naturally acquired PfATRP-specific antibodies.
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Affiliation(s)
- Emmanuel Amlabu
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
- Department of Biochemistry, Kogi State University, Anyigba, Nigeria
| | - Philip Ilani
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Grace Opoku
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Prince B. Nyarko
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Evelyn Quansah
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Laty G. Thiam
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Manfred Anim
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Reuben Ayivor-Djanie
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
- Department of Biomedical Sciences, SBBS, University of Health and Allied Sciences, Ho, Ghana
| | - Ojo-ajogu Akuh
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Henrietta Mensah-Brown
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
| | - Julian C. Rayner
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
| | - Gordon A. Awandare
- West African Center for Cell Biology of Infectious Pathogens, University of Ghana, Accra, Ghana
- Department of Biochemistry, Cell and Molecular Biology, College of Basic and Applied Sciences, University of Ghana, Accra, Ghana
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8
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Odhiambo G, Bergmann-Leitner E, Maraka M, Wanjala CNL, Duncan E, Waitumbi J, Andagalu B, Jura WGZO, Dutta S, Angov E, Ogutu BR, Kamau E, Ochiel D. Correlation Between Malaria-Specific Antibody Profiles and Responses to Artemisinin Combination Therapy for Treatment of Uncomplicated Malaria in Western Kenya. J Infect Dis 2020; 219:1969-1979. [PMID: 30649381 DOI: 10.1093/infdis/jiz027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2018] [Accepted: 01/11/2019] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND The impact of preexisting immunity on the efficacy of artemisinin combination therapy must be examined to monitor resistance, and for implementation of new treatment strategies. METHODS Serum samples obtained from a clinical trial in Western Kenya randomized to receive artemether-lumefantrine (AL) or artesunate-mefloquine (ASMQ) were screened for total immunoglobulin G against preerythrocytic and erythrocytic antigens. The association and correlation between different variables, and impact of preexisting immunity on parasite slope half-life (t½) was determined. RESULTS There was no significant difference in t½, but the number of individuals with lag phase was significantly higher in the AL than in the ASMQ arm (29 vs 13, respectively; P < .01). Circumsporozoite protein-specific antibodies correlate positively with t½ (AL, P = .03; ASMQ, P = .09), but negatively with clearance rate in both study arms (AL, P = .16; ASMQ, P = .02). The t½ correlated negatively with age in ASMQ group. When stratified based on t½, the antibody titers against circumsporozoite protein and merozoite surface protein 1 were significantly higher in participants who cleared parasites rapidly in the AL group (P = .01 and P = .02, respectively). CONCLUSION Data presented here define immunoprofiles associated with distinct responses to 2 different antimalarial drugs, revealing impact of preexisting immunity on the efficacy of artemisinin combination therapy regimens in a malaria-holoendemic area. CLINICAL TRIALS REGISTRATION NCT01976780.
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Affiliation(s)
- Geoffrey Odhiambo
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu.,Maseno University School of Physical and Biological Sciences Zoology Department, Maseno, Kenya
| | - Elke Bergmann-Leitner
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland
| | - Moureen Maraka
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu
| | - Christine N L Wanjala
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu.,Maseno University School of Physical and Biological Sciences Zoology Department, Maseno, Kenya
| | - Elizabeth Duncan
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland
| | - John Waitumbi
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu
| | - Ben Andagalu
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu
| | - Walter G Z O Jura
- Maseno University School of Physical and Biological Sciences Zoology Department, Maseno, Kenya
| | - Sheetij Dutta
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland
| | - Evelina Angov
- Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland
| | - Bernhards R Ogutu
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu.,Kenya Medical Research Institute, Nairobi
| | - Edwin Kamau
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu.,Malaria Vaccine Branch, Walter Reed Army Institute of Research, Silver Spring, Maryland
| | - Daniel Ochiel
- Department of Emerging and Infectious Diseases, United States Army Medical Research Directorate-Africa, Kenya Medical Research Institute/Walter Reed Project , Kisumu.,Maseno University School of Physical and Biological Sciences Zoology Department, Maseno, Kenya
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Najer A, Palivan CG, Beck HP, Meier W. Challenges in Malaria Management and a Glimpse at Some Nanotechnological Approaches. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1052:103-112. [PMID: 29785484 DOI: 10.1007/978-981-10-7572-8_9] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Malaria is a devastating infectious disease transmitted by mosquitoes, affecting millions of people and killing about half a million children each year. Despite tremendous progress in the control and elimination of malaria within the past years, there are still considerable challenges to be solved. To name a few, drug-resistant parasites, insecticide-resistant mosquitoes and the difficulty to formulate a potent malaria vaccine need to be addressed with new strategies to achieve the final goal of malaria eradication. Nanotechnology-researching and designing innovative structures at the nanoscale-is a promising contemporary technology that is being applied to a vast number of biomedical problems. In the case of malaria, nanotechnology provides tools to design strategies to target drug molecules to specific stages of the parasite, treat drug-resistant parasites, resolve severe malaria, increase vaccine efficacies and combinations thereof. This chapter introduces malaria, discusses current challenges of malaria control and relates these challenges to some potential solutions provided by the nanotechnology field.
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Affiliation(s)
- Adrian Najer
- Department of Chemistry, University of Basel, 4056, Basel, Switzerland.,Swiss Tropical and Public Health Institute, University of Basel, 4002, Basel, Switzerland
| | | | - Hans-Peter Beck
- Swiss Tropical and Public Health Institute, University of Basel, 4002, Basel, Switzerland
| | - Wolfgang Meier
- Department of Chemistry, University of Basel, 4056, Basel, Switzerland.
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10
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Mechanisms of naturally acquired immunity to P. falciparum and approaches to identify merozoite antigen targets. Parasitology 2017; 145:839-847. [PMID: 29144217 DOI: 10.1017/s0031182017001949] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Malaria is one the most serious infectious diseases with over 200 million clinical cases annually. Most cases of the severe disease are caused by Plasmodium falciparum. The blood stage of Plasmodium parasite is entirely responsible for malaria-associated pathology. The population most susceptible to severe malaria are children under the age of 5, with low levels of immunity. It is only after many years of repeated exposure that individuals living in endemic areas develop clinical immunity. This form of protection prevents clinical episodes by substantially reducing parasite burden. Naturally acquired immunity predominantly targets blood-stage parasites with antibody responses being the main mediators of protection. The targets of clinical immunity are the extracellular merozoite and the infected erythrocyte surface, with the extremely diverse PfEMP1 proteins the main target here. This observation provides a strong rationale that an effective anti-malaria vaccine targeting blood-stage parasites is achievable. Thus the identification of antigenic targets of naturally acquired immunity remains an important step towards the formulation of novel vaccine combinations before testing their efficacy in clinical trials. This review summarizes the main findings to date defining antigenic targets present on the extracellular merozoite associated with naturally acquired immunity to P. falciparum malaria.
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Merozoite Surface Protein 1 from Plasmodium falciparum Is a Major Target of Opsonizing Antibodies in Individuals with Acquired Immunity against Malaria. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00155-17. [PMID: 28877929 DOI: 10.1128/cvi.00155-17] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Accepted: 08/31/2017] [Indexed: 11/20/2022]
Abstract
Naturally acquired immunity against malaria is largely mediated by serum antibodies controlling levels of blood-stage parasites. A limited understanding of the antigenic targets and functional mechanisms of protective antibodies has hampered the development of efficient malaria vaccines. Besides directly inhibiting the growth of Plasmodium parasites, antibodies can opsonize merozoites and recruit immune effector cells such as monocytes and neutrophils. Antibodies against the vaccine candidate merozoite surface protein 1 (MSP-1) are acquired during natural infections and have been associated with protection against malaria in several epidemiological studies. Here we analyzed serum antibodies from semi-immune individuals from Burkina Faso for their potential (i) to directly inhibit the growth of P. falciparum blood stages in vitro and (ii) to opsonize merozoites and to induce the antibody-dependent respiratory burst (ADRB) activity of neutrophils. While a few sera that directly inhibited the growth of P. falciparum blood stages were identified, immunoglobulin G (IgG) from all individuals clearly mediated the activation of neutrophils. The level of neutrophil activation correlated with levels of antibodies to MSP-1, and affinity-purified MSP-1-specific antibodies elicited ADRB activity. Furthermore, immunization of nonhuman primates with recombinant full-size MSP-1 induced antibodies that efficiently opsonized P. falciparum merozoites. Reversing the function by preincubation with recombinant antigens allowed us to quantify the contribution of MSP-1 to the antiparasitic effect of serum antibodies. Our data suggest that MSP-1, especially the partially conserved subunit MSP-183, is a major target of opsonizing antibodies acquired during natural exposure to malaria. Induction of opsonizing antibodies might be a crucial effector mechanism for MSP-1-based malaria vaccines.
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Najer A, Wu D, Nussbaumer MG, Schwertz G, Schwab A, Witschel MC, Schäfer A, Diederich F, Rottmann M, Palivan CG, Beck HP, Meier W. An amphiphilic graft copolymer-based nanoparticle platform for reduction-responsive anticancer and antimalarial drug delivery. NANOSCALE 2016; 8:14858-69. [PMID: 27452350 DOI: 10.1039/c6nr04290b] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
Medical applications of anticancer and antimalarial drugs often suffer from low aqueous solubility, high systemic toxicity, and metabolic instability. Smart nanocarrier-based drug delivery systems provide means of solving these problems at once. Herein, we present such a smart nanoparticle platform based on self-assembled, reduction-responsive amphiphilic graft copolymers, which were successfully synthesized through thiol-disulfide exchange reaction between thiolated hydrophilic block and pyridyl disulfide functionalized hydrophobic block. These amphiphilic graft copolymers self-assembled into nanoparticles with mean diameters of about 30-50 nm and readily incorporated hydrophobic guest molecules. Fluorescence correlation spectroscopy (FCS) was used to study nanoparticle stability and triggered release of a model compound in detail. Long-term colloidal stability and model compound retention within the nanoparticles was found when analyzed in cell media at body temperature. In contrast, rapid, complete reduction-triggered disassembly and model compound release was achieved within a physiological reducing environment. The synthesized copolymers revealed no intrinsic cellular toxicity up to 1 mg mL(-1). Drug-loaded reduction-sensitive nanoparticles delivered a hydrophobic model anticancer drug (doxorubicin, DOX) to cancer cells (HeLa cells) and an experimental, metabolically unstable antimalarial drug (the serine hydroxymethyltransferase (SHMT) inhibitor (±)-1) to Plasmodium falciparum-infected red blood cells (iRBCs), with higher efficacy compared to similar, non-sensitive drug-loaded nanoparticles. These responsive copolymer-based nanoparticles represent a promising candidate as smart nanocarrier platform for various drugs to be applied to different diseases, due to the biocompatibility and biodegradability of the hydrophobic block, and the protein-repellent hydrophilic block.
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Affiliation(s)
- Adrian Najer
- Department of Chemistry, University of Basel, Klingelbergstrasse 80, CH-4056 Basel, Switzerland.
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Langhorne J, Duffy PE. Expanding the antimalarial toolkit: Targeting host-parasite interactions. J Exp Med 2016; 213:143-53. [PMID: 26834158 PMCID: PMC4749928 DOI: 10.1084/jem.20151677] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 12/21/2015] [Indexed: 12/27/2022] Open
Abstract
Recent successes in malaria control are threatened by drug-resistant Plasmodium parasites and insecticide-resistant Anopheles mosquitoes, and first generation vaccines offer only partial protection. New research approaches have highlighted host as well as parasite molecules or pathways that could be targeted for interventions. In this study, we discuss host–parasite interactions at the different stages of the Plasmodium life cycle within the mammalian host and the potential for therapeutics that prevent parasite migration, invasion, intracellular growth, or egress from host cells, as well as parasite-induced pathology.
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Affiliation(s)
- Jean Langhorne
- Mill Hill Laboratory, The Francis Crick Institute, London NW7 1AA, England, UK
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20852
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Increased exposure to Plasmodium chabaudi antigens sustains cross-reactivity and avidity of antibodies binding Nippostrongylus brasiliensis: dissecting cross-phylum cross-reactivity in a rodent model. Parasitology 2015; 142:1703-14. [DOI: 10.1017/s0031182015001390] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
SUMMARYMounting an antibody response capable of discriminating amongst and appropriately targeting different parasites is crucial in host defence. However, cross-reactive antibodies that recognize (bind to) multiple parasite species are well documented. We aimed to determine if a higher inoculating dose of one species, and thus exposure to larger amounts of antigen over a longer period of time, would fine-tune responses to that species and reduce cross-reactivity. Using the Plasmodium chabaudi chabaudi (Pcc)–Nippostrongylus brasiliensis (Nb) co-infection model in BALB/c mice, in which we previously documented cross-reactive antibodies, we manipulated the inoculating dose of Pcc across 4 orders of magnitude. We investigated antigen-specific and cross-reactive antibody responses against crude and defined recombinant antigens by enzyme linked immunosorbent assay, Western blot and antibody depletion assays. Contrary to our hypothesis that increasing exposure to Pcc would reduce cross-reactivity to Nb, we found evidence for increased avidity of a subpopulation of antibodies that recognized shared antigens. Western blot indicated proteins of apparent monomer molecular mass 28 and 98 kDa in both Nb and Pcc antigen preparations and also an Nb protein of similar size to recombinant Pcc antigen, merozoite surface protein-119. The implications of antibodies binding antigen from such phylogenetically distinct parasites are discussed.
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15
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Griffiths EC, Fairlie-Clarke K, Allen JE, Metcalf CJE, Graham AL. Bottom-up regulation of malaria population dynamics in mice co-infected with lung-migratory nematodes. Ecol Lett 2015; 18:1387-96. [PMID: 26477454 DOI: 10.1111/ele.12534] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 07/20/2015] [Accepted: 09/18/2015] [Indexed: 12/22/2022]
Abstract
When and how populations are regulated by bottom up vs. top down processes, and how those processes are affected by co-occurring species, are poorly characterised across much of ecology. We are especially interested in the community ecology of parasites that must share a host. Here, we quantify how resources and immunity affect parasite propagation in experiments in near-replicate 'mesocosms'' - i.e. mice infected with malaria (Plasmodium chabaudi) and nematodes (Nippostrongylus brasiliensis). Nematodes suppressed immune responses against malaria, and yet malaria populations were smaller in co-infected hosts. Further analyses of within-host epidemiology revealed that nematode co-infection altered malaria propagation by suppressing target cell availability. This is the first demonstration that bottom-up resource regulation may have earlier and stronger effects than top-down immune mechanisms on within-host community dynamics. Our findings demonstrate the potential power of experimental ecology to disentangle mechanisms of population regulation in complex communities.
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Affiliation(s)
- Emily C Griffiths
- Department of Entomology, Gardner Hall, Derieux Place, Raleigh NC 27695-7613, USA
| | - Karen Fairlie-Clarke
- Institute of Biodiversity, Animal Health & Comparative Medicine, College of Medical and Veterinary Life Sciences, University of Glasgow, Glasgow, G61 1QH, UK
| | - Judith E Allen
- Institute of Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, EH8 9YL, UK
| | - C Jessica E Metcalf
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.,Fogarty International Center, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Andrea L Graham
- Department of Ecology and Evolutionary Biology, Princeton University, Princeton, NJ, 08544, USA.,Fogarty International Center, National Institutes of Health, Bethesda, MD, 20892, USA
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Farooq F, Bergmann-Leitner ES. Immune Escape Mechanisms are Plasmodium's Secret Weapons Foiling the Success of Potent and Persistently Efficacious Malaria Vaccines. Clin Immunol 2015; 161:136-43. [PMID: 26342537 DOI: 10.1016/j.clim.2015.08.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 08/27/2015] [Indexed: 10/23/2022]
Abstract
Despite decades of active research, an efficacious vaccine mediating long-term protection is still not available. This review highlights various mechanisms and the different facets by which the parasites outsmart the immune system. An understanding of how the parasites escape immune recognition and interfere with the induction of a protective immune response that provides sterilizing immunity will be crucial to vaccine design.
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Affiliation(s)
- Fouzia Farooq
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910
| | - Elke S Bergmann-Leitner
- Malaria Vaccine Branch, U.S. Military Malaria Research Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910.
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Maskus DJ, Bethke S, Seidel M, Kapelski S, Addai-Mensah O, Boes A, Edgü G, Spiegel H, Reimann A, Fischer R, Barth S, Klockenbring T, Fendel R. Isolation, production and characterization of fully human monoclonal antibodies directed to Plasmodium falciparum MSP10. Malar J 2015; 14:276. [PMID: 26174014 PMCID: PMC4502606 DOI: 10.1186/s12936-015-0797-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Accepted: 07/07/2015] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Semi-immunity against the malaria parasite is defined by a protection against clinical episodes of malaria and is partially mediated by a repertoire of inhibitory antibodies directed against the blood stage of Plasmodium falciparum, in particular against surface proteins of merozoites, the invasive form of the parasite. Such antibodies may be used for preventive or therapeutic treatment of P. falciparum malaria. Here, the isolation and characterization of novel human monoclonal antibodies (humAbs) for such applications is described. METHODS B lymphocytes had been selected by flow cytometry for specificity against merozoite surface proteins, including the merozoite surface protein 10 (MSP10). After Epstein-Barr virus (EBV) transformation and identification of promising resulting lymphoblastoid cell lines (LCLs), human immunoglobulin heavy and light chain variable regions (Vh or Vl regions) were secured, cloned into plant expression vectors and transiently produced in Nicotiana benthamiana in the context of human full-size IgG1:κ. The specificity and the affinity of the generated antibodies were assessed by ELISA, dotblot and surface plasmon resonance (SPR) spectroscopy. The growth inhibitory activity was evaluated based on growth inhibition assays (GIAs) using the parasite strain 3D7A. RESULTS Supernatants from two LCLs, 5E8 and 5F6, showed reactivity against the second (5E8) or first (5F6) epidermal growth factor (EGF)-like domain of MSP10. The isolated V regions were recombinantly expressed in their natural pairing as well as in combination with each other. The resulting recombinant humAbs showed affinities of 9.27 × 10(-7) M [humAb10.1 (H5F6:κ5E8)], 5.46 × 10(-9) M [humAb10.2 (H5F6:κ5F6)] and 4.34 × 10(-9) M [humAb10.3 (H5E8:κ5E8)]. In GIAs, these antibodies exhibited EC50 values of 4.1 mg/ml [95% confidence interval (CI) 2.6-6.6 mg/ml], 6.9 mg/ml (CI 5.5-8.6 mg/ml) and 9.5 mg/ml (CI 5.5-16.4 mg/ml), respectively. CONCLUSION This report describes a platform for the isolation of human antibodies from semi-immune blood donors by EBV transformation and their subsequent characterization after transient expression in plants. To our knowledge, the presented antibodies are the first humAbs directed against P. falciparum MSP10 to be described. They recognize the EGF-like folds of MSP10 and bind these with high affinity. Moreover, these antibodies inhibit P. falciparum 3D7A growth in vitro.
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Affiliation(s)
- Dominika J Maskus
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Susanne Bethke
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Melanie Seidel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Stephanie Kapelski
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Otchere Addai-Mensah
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
- Faculty of Allied Health Sciences, Kwame Nkrumah University of Science and Technology, Kumasi, Ghana.
| | - Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Güven Edgü
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
| | - Stefan Barth
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Aachen, Germany.
| | - Torsten Klockenbring
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
| | - Rolf Fendel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany.
- Institute for Molecular Biotechnology, RWTH Aachen University, Aachen, Germany.
- Department of Experimental Medicine and Immunotherapy, Institute for Applied Medical Engineering at RWTH Aachen University and Hospital, Aachen, Germany.
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18
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Sonaimuthu P, Cheong FW, Chin LC, Mahmud R, Fong MY, Lau YL. Detection of human malaria using recombinant Plasmodium knowlesi merozoire surface protein-1 (MSP-1₁₉) expressed in Escherichia coli. Exp Parasitol 2015; 153:118-22. [PMID: 25812552 DOI: 10.1016/j.exppara.2015.03.010] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2014] [Revised: 03/10/2015] [Accepted: 03/20/2015] [Indexed: 01/30/2023]
Abstract
Malaria remains one of the world's most important infectious diseases and is responsible for enormous mortality and morbidity. Human infection with Plasmodium knowlesi is widely distributed in Southeast Asia. Merozoite surface protein-1₁₉ (MSP-1₁₉), which plays an important role in protective immunity against asexual blood stage malaria parasites, appears as a leading immunogenic antigen of Plasmodium sp. We evaluated the sensitivity and specificity of recombinant P. knowlesi MSP-1₁₉ (rMSP-1₁₉) for detection of malarial infection. rMSP-1₁₉ was expressed in Escherichia coli expression system and the purified rMSP-1₁₉ was evaluated with malaria, non-malaria and healthy human serum samples (n = 215) in immunoblots. The sensitivity of rMSP-1₁₉ for detection of P. knowlesi, Plasmodium falciparum, Plasmodium vivax and Plasmodium ovale infection was 95.5%, 75.0%, 85.7% and 100%, respectively. rMSP-1₁₉ did not react with all the non-malaria and healthy donor sera, which represents 100% specificity. The rMSP-1₁₉ could be used as a potential antigen in serodiagnosis of malarial infection in humans.
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Affiliation(s)
| | - Fei Wen Cheong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Lit Chein Chin
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia
| | - Rohela Mahmud
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, University of Malaya, Kuala Lumpur, Malaysia; Tropical Disease Research and Education Centre (TIDREC), Faculty of Medicine, University of Malaya, Kuala Lumpur 50603, Malaysia.
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Marques J, Moles E, Urbán P, Prohens R, Busquets MA, Sevrin C, Grandfils C, Fernàndez-Busquets X. Application of heparin as a dual agent with antimalarial and liposome targeting activities toward Plasmodium-infected red blood cells. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2014; 10:1719-28. [DOI: 10.1016/j.nano.2014.06.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2014] [Revised: 05/28/2014] [Accepted: 06/04/2014] [Indexed: 02/06/2023]
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20
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Raj DK, Nixon CP, Nixon CE, Dvorin JD, DiPetrillo CG, Pond-Tor S, Wu HW, Jolly G, Pischel L, Lu A, Michelow IC, Cheng L, Conteh S, McDonald EA, Absalon S, Holte SE, Friedman JF, Fried M, Duffy PE, Kurtis JD. Antibodies to PfSEA-1 block parasite egress from RBCs and protect against malaria infection. Science 2014; 344:871-7. [PMID: 24855263 DOI: 10.1126/science.1254417] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Novel vaccines are urgently needed to reduce the burden of severe malaria. Using a differential whole-proteome screening method, we identified Plasmodium falciparum schizont egress antigen-1 (PfSEA-1), a 244-kilodalton parasite antigen expressed in schizont-infected red blood cells (RBCs). Antibodies to PfSEA-1 decreased parasite replication by arresting schizont rupture, and conditional disruption of PfSEA-1 resulted in a profound parasite replication defect. Vaccination of mice with recombinant Plasmodium berghei PbSEA-1 significantly reduced parasitemia and delayed mortality after lethal challenge with the Plasmodium berghei strain ANKA. Tanzanian children with antibodies to recombinant PfSEA-1A (rPfSEA-1A) did not experience severe malaria, and Kenyan adolescents and adults with antibodies to rPfSEA-1A had significantly lower parasite densities than individuals without these antibodies. By blocking schizont egress, PfSEA-1 may synergize with other vaccines targeting hepatocyte and RBC invasion.
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Affiliation(s)
- Dipak K Raj
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Christian P Nixon
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Christina E Nixon
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Christen G DiPetrillo
- Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Sunthorn Pond-Tor
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Hai-Wei Wu
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA. Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Grant Jolly
- Department of Pathology and Laboratory Medicine, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02906, USA
| | - Lauren Pischel
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Ailin Lu
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Ian C Michelow
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA. Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Ling Cheng
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Solomon Conteh
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20892, USA
| | - Emily A McDonald
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Sabrina Absalon
- Division of Infectious Diseases, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA
| | - Sarah E Holte
- Fred Hutchinson Cancer Research Center Program in Biostatistics and Biomathematics, Department of Biostatistics and Global Health, University of Washington, Seattle, WA 98109, USA
| | - Jennifer F Friedman
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA. Department of Pediatrics, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA
| | - Michal Fried
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20892, USA
| | - Patrick E Duffy
- Laboratory of Malaria Immunology and Vaccinology, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD 20892, USA
| | - Jonathan D Kurtis
- Center for International Health Research, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02903, USA. Department of Pathology and Laboratory Medicine, Rhode Island Hospital, The Warren Alpert Medical School of Brown University, Providence, RI 02906, USA.
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Use of poly(amidoamine) drug conjugates for the delivery of antimalarials to Plasmodium. J Control Release 2014; 177:84-95. [DOI: 10.1016/j.jconrel.2013.12.032] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2013] [Revised: 12/19/2013] [Accepted: 12/21/2013] [Indexed: 11/21/2022]
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22
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Cheong FW, Fong MY, Lau YL, Mahmud R. Immunogenicity of bacterial-expressed recombinant Plasmodium knowlesi merozoite surface protein-142 (MSP-142). Malar J 2013; 12:454. [PMID: 24354660 PMCID: PMC3878241 DOI: 10.1186/1475-2875-12-454] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 12/17/2013] [Indexed: 11/10/2022] Open
Abstract
Background Plasmodium knowlesi is the fifth Plasmodium species that can infect humans. The Plasmodium merozoite surface protein-142 (MSP-142) is a potential candidate for malaria vaccine. However, limited studies have focused on P. knowlesi MSP-142. Methods A ~42 kDa recombinant P. knowlesi MSP-142 (pkMSP-142) was expressed using an Escherichia coli system. The purified pkMSP-142 was evaluated with malaria and non-malaria human patient sera (n = 189) using Western blots and ELISA. The immunogenicity of pkMSP-142 was evaluated in mouse model. Results The purified pkMSP-142 had a sensitivity of 91.0% for detection of human malaria in both assays. Specificity was 97.5 and 92.6% in Western blots and ELISA, respectively. Levels of cytokine interferon-gamma, interleukin-2, interleukin-4, and interleukin-10 significantly increased in pkMSP-142-immunized mice as compared to the negative control mice. pkMSP-142-raised antibody had high endpoint titres, and the IgG isotype distribution was IgG1 > IgG2b > IgG3 > IgG2a. Conclusions pkMSP-142 was highly immunogenic and able to detect human malaria. Hence, pkMSP-142 would be a useful candidate for malaria vaccine development and seroprevalence studies.
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Affiliation(s)
| | - Mun Yik Fong
- Department of Parasitology, Faculty of Medicine, University of Malaya, 50603, Kuala Lumpur, Malaysia.
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Fairlie-Clarke KJ, Allen JE, Read AF, Graham AL. Quantifying variation in the potential for antibody-mediated apparent competition among nine genotypes of the rodent malaria parasite Plasmodium chabaudi. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2013; 20:270-5. [PMID: 24056014 PMCID: PMC3898986 DOI: 10.1016/j.meegid.2013.09.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 09/10/2013] [Accepted: 09/11/2013] [Indexed: 01/01/2023]
Abstract
Within-host competition among parasite genotypes affects epidemiology as well as the evolution of virulence. In the rodent malaria Plasmodium chabaudi, competition among genotypes, as well as clone-specific and clone-transcending immunity are well documented. However, variation among genotypes in the induction of antibodies is not well understood, despite the important role of antibodies in the clearance of malaria infection. Here, we quantify the potential for antibodies induced by one clone to bind another (i.e., to cause antibody-mediated apparent competition) for nine genetically distinct P. chabaudi clones. We hypothesised that clones would vary in the strength of antibody induction, and that the propensity for clone-transcending immunity between a pair of clones would increase with increasing genetic relatedness at key antigenic loci. Using serum collected from mice 35 days post-infection, we measured titres of antibody to an unrelated antigen, Keyhole Limpet Haemocyanin (KLH), and two malaria antigens: recombinant Apical Membrane Antigen-1 (AMA-1) and Merozoite Surface Protein-119 (MSP-119). Amino acid sequence homology within each antigenic locus was used as a measure of relatedness. We found significant parasite genetic variation for the strength of antibody induction. We also found that relatedness at MSP-119 but not AMA-1 predicted clone-transcending binding. Our results help explain the outcome of chronic-phase mixed infections and generate testable predictions about the pairwise competitive ability of P. chabaudi clones.
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Affiliation(s)
- Karen J Fairlie-Clarke
- Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, King's Buildings, University of Edinburgh, Edinburgh, UK.
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Putaporntip C, Thongaree S, Jongwutiwes S. Differential sequence diversity at merozoite surface protein-1 locus of Plasmodium knowlesi from humans and macaques in Thailand. INFECTION GENETICS AND EVOLUTION 2013; 18:213-9. [DOI: 10.1016/j.meegid.2013.05.019] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 05/16/2013] [Accepted: 05/20/2013] [Indexed: 11/29/2022]
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Otsyula N, Angov E, Bergmann-Leitner E, Koech M, Khan F, Bennett J, Otieno L, Cummings J, Andagalu B, Tosh D, Waitumbi J, Richie N, Shi M, Miller L, Otieno W, Otieno GA, Ware L, House B, Godeaux O, Dubois MC, Ogutu B, Ballou WR, Soisson L, Diggs C, Cohen J, Polhemus M, Heppner DG, Ockenhouse CF, Spring MD. Results from tandem Phase 1 studies evaluating the safety, reactogenicity and immunogenicity of the vaccine candidate antigen Plasmodium falciparum FVO merozoite surface protein-1 (MSP1(42)) administered intramuscularly with adjuvant system AS01. Malar J 2013; 12:29. [PMID: 23342996 PMCID: PMC3582548 DOI: 10.1186/1475-2875-12-29] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2012] [Accepted: 01/14/2013] [Indexed: 01/06/2023] Open
Abstract
Background The development of an asexual blood stage vaccine against Plasmodium falciparum malaria based on the major merozoite surface protein-1 (MSP1) antigen is founded on the protective efficacy observed in preclinical studies and induction of invasion and growth inhibitory antibody responses. The 42 kDa C-terminus of MSP1 has been developed as the recombinant protein vaccine antigen, and the 3D7 allotype, formulated with the Adjuvant System AS02A, has been evaluated extensively in human clinical trials. In preclinical rabbit studies, the FVO allele of MSP142 has been shown to have improved immunogenicity over the 3D7 allele, in terms of antibody titres as well as growth inhibitory activity of antibodies against both the heterologous 3D7 and homologous FVO parasites. Methods Two Phase 1 clinical studies were conducted to examine the safety, reactogenicity and immunogenicity of the FVO allele of MSP142 in the adjuvant system AS01 administered intramuscularly at 0-, 1-, and 2-months: one in the USA and, after evaluation of safety data results, one in Western Kenya. The US study was an open-label, dose escalation study of 10 and 50 μg doses of MSP142 in 26 adults, while the Kenya study, evaluating 30 volunteers, was a double-blind, randomized study of only the 50 μg dose with a rabies vaccine comparator. Results In these studies it was demonstrated that this vaccine formulation has an acceptable safety profile and is immunogenic in malaria-naïve and malaria-experienced populations. High titres of anti-MSP1 antibodies were induced in both study populations, although there was a limited number of volunteers whose serum demonstrated significant inhibition of blood-stage parasites as measured by growth inhibition assay. In the US volunteers, the antibodies generated exhibited better cross-reactivity to heterologous MSP1 alleles than a MSP1-based vaccine (3D7 allele) previously tested at both study sites. Conclusions Given that the primary effector mechanism for blood stage vaccine targets is humoral, the antibody responses demonstrated to this vaccine candidate, both quantitative (total antibody titres) and qualitative (functional antibodies inhibiting parasite growth) warrant further consideration of its application in endemic settings. Trial registrations Clinical Trials NCT00666380
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Affiliation(s)
- Nekoye Otsyula
- Walter Reed Project, Kenya Medical Research Institute, Kisumu, Kenya
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Bergmann-Leitner ES, Duncan EH, Mease RM, Angov E. Impact of pre-existing MSP1(42)-allele specific immunity on potency of an erythrocytic Plasmodium falciparum vaccine. Malar J 2012; 11:315. [PMID: 22958482 PMCID: PMC3502560 DOI: 10.1186/1475-2875-11-315] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/30/2012] [Indexed: 01/03/2023] Open
Abstract
Background MSP1 is the major surface protein on merozoites and a prime candidate for a blood stage malaria vaccine. Preclinical and seroepidemiological studies have implicated antibodies to MSP1 in protection against blood stage parasitaemia and/or reduced parasite densities, respectively. Malaria endemic areas have multiple strains of Plasmodium falciparum circulating at any given time, giving rise to complex immune responses, an issue which is generally not addressed in clinical trials conducted in non-endemic areas. A lack of understanding of the effect of pre-existing immunity to heterologous parasite strains may significantly contribute to vaccine failure in the field. The purpose of this study was to model the effect of pre-existing immunity to MSP142 on the immunogenicity of blood-stage malaria vaccines based on alternative MSP1 alleles. Methods Inbred and outbred mice were immunized with various recombinant P. falciparum MSP142 proteins that represent the two major alleles of MSP142, MAD20 (3D7) and Wellcome (K1, FVO). Humoral immune responses were analysed by ELISA and LuminexTM, and functional activity of induced MSP142-specific antibodies was assessed by growth inhibition assays. T-cell responses were characterized using ex vivo ELISpot assays. Results Analysis of the immune responses induced by various immunization regimens demonstrated a strong allele-specific response at the T cell level in both inbred and outbred mice. The success of heterologous regimens depended on the degree of homology of the N-terminal p33 portion of the MSP142, likely due to the fact that most T cell epitopes reside in this part of the molecule. Analysis of humoral immune responses revealed a marked cross-reactivity between the alleles. Functional analyses showed that some of the heterologous regimens induced antibodies with improved growth inhibitory activities. Conclusion The development of a more broadly efficacious MSP1 based vaccine may be hindered by clonally imprinted p33 responses mainly restricted at the T cell level. In this study, the homology of the p33 sequence between the clonally imprinted response and the vaccine allele determines the magnitude of vaccine induced responses.
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Affiliation(s)
- Elke S Bergmann-Leitner
- Malaria Vaccine Branch, US Military Malaria Vaccine Program, Walter Reed Army Institute of Research, Silver Spring, MD 20910, USA.
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Plasmodium falciparum 19-kilodalton merozoite surface protein 1 (MSP1)-specific antibodies that interfere with parasite growth in vitro can inhibit MSP1 processing, merozoite invasion, and intracellular parasite development. Infect Immun 2011; 80:1280-7. [PMID: 22202121 DOI: 10.1128/iai.05887-11] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Merozoite surface protein 1 (MSP1) is a target for malaria vaccine development. Antibodies to the 19-kDa carboxy-terminal region referred to as MSP1(19) inhibit erythrocyte invasion and parasite growth, with some MSP1-specific antibodies shown to inhibit the proteolytic processing of MSP1 that occurs at invasion. We investigated a series of antibodies purified from rabbits immunized with MSP1(19) and AMA1 recombinant proteins for their ability to inhibit parasite growth, initially looking at MSP1 processing. Although significant inhibition of processing was mediated by several of the antibody samples, there was no clear relationship with overall growth inhibition by the same antibodies. However, no antibody samples inhibited processing but not invasion, suggesting that inhibition of MSP1 processing contributes to but is not the only mechanism of antibody-mediated inhibition of invasion and growth. Examining other mechanisms by which MSP1-specific antibodies inhibit parasite growth, we show that MSP1(19)-specific antibodies are taken up into invaded erythrocytes, where they persist for significant periods and result in delayed intracellular parasite development. This delay may result from antibody interference with coalescence of MSP1(19)-containing vesicles with the food vacuole. Antibodies raised against a modified recombinant MSP1(19) sequence were more efficient at delaying intracellular growth than those to the wild-type protein. We propose that antibodies specific for MSP1(19) can mediate inhibition of parasite growth by at least three mechanisms: inhibition of MSP1 processing, direct inhibition of invasion, and inhibition of parasite development following invasion. The balance between mechanisms may be modulated by modifying the immunogen used to induce the antibodies.
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Patarroyo ME, Bermúdez A, Patarroyo MA. Structural and Immunological Principles Leading to Chemically Synthesized, Multiantigenic, Multistage, Minimal Subunit-Based Vaccine Development. Chem Rev 2011; 111:3459-507. [DOI: 10.1021/cr100223m] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Manuel Elkin Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad Nacional de Colombia
| | - Adriana Bermúdez
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
| | - Manuel Alfonso Patarroyo
- Fundación Instituto de Inmunología de Colombia (FIDIC), Carrera 50, No. 26-00, Bogotá, Colombia
- Universidad del Rosario
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Urbán P, Estelrich J, Cortés A, Fernàndez-Busquets X. A nanovector with complete discrimination for targeted delivery to Plasmodium falciparum-infected versus non-infected red blood cells in vitro. J Control Release 2011; 151:202-11. [PMID: 21223986 DOI: 10.1016/j.jconrel.2011.01.001] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2010] [Revised: 12/22/2010] [Accepted: 01/04/2011] [Indexed: 12/22/2022]
Abstract
Current administration methods of antimalarial drugs deliver the free compound in the blood stream, where it can be unspecifically taken up by all cells, and not only by Plasmodium-infected red blood cells (pRBCs). Nanosized carriers have been receiving special attention with the aim of minimizing the side effects of malaria therapy by increasing drug bioavailability and selectivity. Liposome encapsulation has been assayed for the delivery of compounds against murine malaria, but there is a lack of cellular studies on the performance of targeted liposomes in specific cell recognition and on the efficacy of cargo delivery, and very little data on liposome-driven antimalarial drug targeting to human-infecting parasites. We have used fluorescence microscopy to assess in vitro the efficiency of liposomal nanocarriers for the targeted delivery of their contents to pRBCs. 200-nm liposomes loaded with quantum dots were covalently functionalized with oriented, specific half-antibodies against P. falciparum late form-infected pRBCs. In less than 90min, liposomes dock to pRBC plasma membranes and release their cargo to the cell. 100.0% of late form-containing pRBCs and 0.0% of non-infected RBCs in P. falciparum cultures are recognized and permeated by the content of targeted immunoliposomes. Liposomes not functionalized with antibodies are also specifically directed to pRBCs, although with less affinity than immunoliposomes. In preliminary assays, the antimalarial drug chloroquine at a concentration of 2nM, ≥10 times below its IC(50) in solution, cleared 26.7±1.8% of pRBCs when delivered inside targeted immunoliposomes.
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Affiliation(s)
- Patricia Urbán
- Nanobioengineering Group, Institute for Bioengineering of Catalonia, Baldiri Reixac 10-12, Barcelona, Spain
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Allele specificity of gamma interferon responses to the carboxyl-terminal region of Plasmodium falciparum merozoite surface protein 1 by Kenyan adults with naturally acquired immunity to malaria. Infect Immun 2010; 78:4431-41. [PMID: 20696832 DOI: 10.1128/iai.00415-10] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cross-sectional seroepidemiological studies of populations naturally exposed to Plasmodium falciparum suggest an association between protection from malaria and circulating antibodies to the carboxyl terminus of merozoite surface protein 1 (MSP1). Questions remain regarding the significance of cell-mediated immunity to MSP1 in conferring protection and inducing immunologic memory. Vaccine constructs have been based on the 42-kDa recombinant MSP1 protein (MSP1(42)), which includes the 19-kDa (MSP1(19)) and 33-kDa (MSP1(33)) fragments containing the major B- and T-cell epitopes, respectively. To evaluate T-cell responses to the MSP1(33) fragment, two libraries of overlapping 18-mer peptides from the 3D7 and FVO MSP1(33) regions were used to screen a cohort of asymptomatic Kenyan adults. Gamma interferon (IFN-γ) measured by enzyme-linked immunospot assay (ELISPOT) at multiple time points assessed the magnitude and stability of these responses. The percentage of individuals with IFN-γ responses to single MSP1(33) peptides ranged from nil to 24%, were clustered among a subset of peptides, and were not consistently recalled over time. In comparison to peptide responses, IFN-γ ELISPOT responses to recombinant MSP1(42) were more prevalent, more frequently elicited by the 3D7 as opposed to the FVO allele, and more stable over time. The prevailing MSP1(33) genotype infection was 3D7, with few mixed infections and no sole FVO infections. This study demonstrates that immunity against MSP1(33) after cumulative natural infections consists of low-magnitude and difficult-to-detect IFN-γ responses. Although immunity against MSP1 alone will not confer protection against malaria, demonstrating a relative and sustained increase in T-cell immunity to MSP1 after vaccination would be a reasonable measurement of vaccine responsiveness.
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Choudhury R, Das P, De T, Chakraborti T. Immunolocalization and characterization of two novel proteases in Leishmania donovani: putative roles in host invasion and parasite development. Biochimie 2010; 92:1274-86. [PMID: 20595064 DOI: 10.1016/j.biochi.2010.05.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2009] [Accepted: 05/25/2010] [Indexed: 10/19/2022]
Abstract
Two novel intracellular proteases having identical molecular mass (58 kDa) were purified from virulent Indian strain of Leishmania donovani by a combination of aprotinin-agarose affinity chromatography, ion exchange chromatography and finally continuous elution electrophoresis. Both of these proteases migrate in SDS-PAGE as a single homogeneous bands suggesting monomeric nature of these proteases. The enzyme activity of one of the proteases was inhibited by serine protease inhibitor aprotinin and another one was inhibited by metalloprotease inhibitor 1, 10 phenanthroline. The purified enzymes were thus of serine protease (SP-Ld) and metalloprotease (MP-Ld) type. The optimal pH for protease activity is 8.0 and 7.5 for SP-Ld and MP-Ld respectively. The temperature optimum for SP-Ld is 28 °C and for MP-Ld is 37 °C showing their thermostability upto 60 °C. Broad substrate (both natural and synthetic) specificity and the effect of Ca2+ upon these enzymes suggested novelty of these proteases. Kinetic data indicate that SP-Ld is of trypsin like as BAPNA appears to be the best substrate and MP-Ld seems to be collagenase type as it degrades azocoll with maximum efficiency. Both immunofluorescence and immune-gold electron microscopy studies revealed that the SP-Ld is localized in the flagellar pocket as well as at the surface of the parasite, whereas MP-Ld is located extensively near the flagellar pocket region. This work also suggests that the uses of anti SP-Ld and anti MP-Ld antibodies are quite significant in interfering with the process of parasite invasion and multiplication respectively. Thus the major role of SP-Ld could be predicted in invasion process as it down regulates the phagocytic activity of macrophages, and MP-Ld appears to play important roles in parasitic development.
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Affiliation(s)
- Rajdeep Choudhury
- Department of Biochemistry and Biophysics, University of Kalyani, Kalyani 741235, West Bengal, India
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Woehlbier U, Epp C, Hackett F, Blackman MJ, Bujard H. Antibodies against multiple merozoite surface antigens of the human malaria parasite Plasmodium falciparum inhibit parasite maturation and red blood cell invasion. Malar J 2010; 9:77. [PMID: 20298576 PMCID: PMC2847572 DOI: 10.1186/1475-2875-9-77] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2009] [Accepted: 03/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Plasmodium falciparum merozoites expose at their surface a large protein complex, which is composed of fragments of merozoite surface protein 1 (MSP-1; called MSP-183, MSP-130, MSP-138, and MSP-142) plus associated processing products of MSP-6 and MSP-7. During erythrocyte invasion this complex, as well as an integral membrane protein called apical membrane antigen-1 (AMA-1), is shed from the parasite surface following specific proteolysis. Components of the MSP-1/6/7 complex and AMA-1 are presently under development as malaria vaccines. METHODS The specificities and effects of antibodies directed against MSP-1, MSP-6, MSP-7 on the growth of blood stage parasites were studied using ELISA and the pLDH-assay. To understand the mode of action of these antibodies, their effects on processing of MSP-1 and AMA-1 on the surface of merozoites were investigated. RESULTS Antibodies targeting epitopes located throughout the MSP-1/6/7 complex interfere with shedding of MSP-1, and as a consequence prevent erythrocyte invasion. Antibodies targeting the MSP-1/6/7 complex have no effect on the processing and shedding of AMA-1 and, similarly, antibodies blocking the shedding of AMA-1 do not affect cleavage of MSP-1, suggesting completely independent functions of these proteins during invasion. Furthermore, some epitopes, although eliciting highly inhibitory antibodies, are only poorly recognized by the immune system when presented in the structural context of the intact antigen. CONCLUSIONS The findings reported provide further support for the development of vaccines based on MSP-1/6/7 and AMA-1, which would possibly include a combination of these antigens.
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Affiliation(s)
- Ute Woehlbier
- Zentrum für Molekulare Biologie (ZMBH), University of Heidelberg, Im Neuenheimer Feld 282, D-69120 Heidelberg, Germany
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Immunogenic properties of a recombinant fusion protein containing the C-terminal 19 kDa of Plasmodium falciparum merozoite surface protein-1 and the innate immunity agonist FliC flagellin of Salmonella typhimurium. Vaccine 2010; 28:2818-26. [PMID: 20170765 DOI: 10.1016/j.vaccine.2010.02.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2009] [Revised: 01/30/2010] [Accepted: 02/03/2010] [Indexed: 12/17/2022]
Abstract
In a recent study, we demonstrated the immunogenic properties of a new malaria vaccine polypeptide based on a 19 kDa C-terminal fragment of the merozoite surface protein-1 (MSP1(19)) from Plasmodium vivax and an innate immunity agonist, the Salmonella enterica serovar Typhimurium flagellin (FliC). Herein, we tested whether the same strategy, based on the MSP1(19) component of the deadly malaria parasite Plasmodium falciparum, could also generate a fusion polypeptide with enhanced immunogenicity. The His(6)FliC-MSP1(19) fusion protein was expressed from a recombinant Escherichia coli and showed preserved in vitro TLR5-binding activity. In contrast to animals injected with His(6)MSP1(19), mice subcutaneously immunised with the recombinant His(6)FliC-MSP1(19) developed strong MSP1(19)-specific systemic antibody responses with a prevailing IgG1 subclass. Incorporation of other adjuvants, such as CpG ODN 1826, complete and incomplete Freund's adjuvants or Quil-A, improved the IgG responses after the second, but not the third, immunising dose. It also resulted in a more balanced IgG subclass response, as evaluated by the IgG1/IgG2c ratio, and higher cell-mediated immune response, as determined by the detection of antigen-specific interferon-gamma secretion by immune spleen cells. MSP1(19)-specific antibodies recognised not only the recombinant protein, but also the native protein expressed on the surface of P. falciparum parasites. Finally, sera from rabbits immunised with the fusion protein alone inhibited the in vitro growth of three different P. falciparum strains. In summary, these results extend our previous observations and further demonstrate that fusion of the innate immunity agonist FliC to Plasmodium antigens is a promising alternative to improve their immunogenicity.
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