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Huang HM, McMorran BJ, Foote SJ, Burgio G. Host genetics in malaria: lessons from mouse studies. Mamm Genome 2018; 29:507-522. [PMID: 29594458 DOI: 10.1007/s00335-018-9744-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2017] [Accepted: 03/22/2018] [Indexed: 01/09/2023]
Abstract
Malaria remains a deadly parasitic disease caused by Plasmodium, claiming almost half a million lives every year. While parasite genetics and biology are often the major targets in many studies, it is becoming more evident that host genetics plays a crucial role in the outcome of the infection. Similarly, Plasmodium infections in mice also rely heavily on the genetic background of the mice, and often correlate with observations in human studies, due to their high genetic homology with humans. As such, murine models of malaria are a useful tool for understanding host responses during Plasmodium infections, as well as dissecting host-parasite interactions through various genetic manipulation techniques. Reverse genetic approach such as quantitative trait loci studies and random mutagenesis screens have been employed to discover novel host genes that affect malaria susceptibility in mouse models, while other targeted studies utilize mouse models to validate observation from human studies. Herein, we review the findings from the past and present studies on murine models of hepatic and erythrocytic stages of malaria and speculate on how the current mouse models benefit from the recent development in CRISPR/Cas9 gene editing technology.
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Affiliation(s)
- Hong Ming Huang
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, ACT, 2601, Australia
| | - Brendan J McMorran
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, ACT, 2601, Australia
| | - Simon J Foote
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, ACT, 2601, Australia
| | - Gaetan Burgio
- Department of Immunology and Infectious Disease, John Curtin School of Medical Research, Australian National University, 131 Garran Road, Canberra, ACT, 2601, Australia.
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Pirahmadi S, Zakeri S, Mehrizi AA, Djadid ND. Analysis of genetic diversity and population structure of gene encoding cell-traversal protein for ookinetes and sporozoites (CelTOS) vaccine candidate antigen in global Plasmodium falciparum populations. INFECTION GENETICS AND EVOLUTION 2018; 59:113-125. [PMID: 29391203 DOI: 10.1016/j.meegid.2018.01.023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Revised: 11/24/2017] [Accepted: 01/25/2018] [Indexed: 10/18/2022]
Abstract
Plasmodium falciparum cell-traversal protein for ookinetes and sporozoites (PfCelTOS) has been reported as one of the most attractive malaria vaccine candidate antigens. To design a broadly effective malaria vaccine based on this antigen, it is crucial to have adequate information on genetic diversity in global PfCelTOS. Therefore, the extent of sequence diversity at the full-length of the pfceltos was assessed among both natural P. falciparum isolates collected from Iran (n = 93) and from available global pfceltos sequence data retrieved from PlasmoDB database (n = 159). Also, recombination, natural selection, the degree of genetic differentiation as well as the predicted immunodominant regions in PfCelTOS were analyzed. In total, 40 SNPs (including 1 synonymous and 39 non-synonymous) were detected in 34 positions, as compared to 3D7 sequence, which led to 66 distinct haplotypes with different frequencies. Among those haplotypes, 34 (51.5%, excluded from further analysis) were singleton haplotype and mostly detected among Senegalese parasite isolates. PfCelt-1 was found as predominant haplotype (32.6% total frequency) that was only detected in Iranian P. falciparum isolates. Nucleotide diversity was low in French Guiana (0.00236 ± 0.00203) and Iranian (0.00259 ± 0.00048) P. falciparum isolates in comparison with African populations. Evidence for positive selection by host immunity and intragenic recombination were detected that are two key factors responsible for gene evolution and genetic diversity of pfceltos gene. The results of Fst analysis and haplotype network revealed that PfCelTOS antigen displayed evident genetic structure between geographical parasite populations. In conclusion, the present analysis demonstrates that there is a limited antigenic diversity and geographic variation in global PfCelTOS, and this finding may be associated with the critical function of this antigen in cell traversal of the parasite in sporozoite and ookinete. Besides, most of the predicted B- and T-cell epitopes were located in the conserved region of the gene, but most of the amino acid replacements were located at the C-terminal region of PfCelTOS. The obtained results in this investigation could provide knowledge for better design of PfCelTOS-based malaria vaccine.
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Affiliation(s)
- Sakineh Pirahmadi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran, Pasteur Avenue, P.O. Box 1316943551, Tehran, Iran
| | - Sedigheh Zakeri
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran, Pasteur Avenue, P.O. Box 1316943551, Tehran, Iran.
| | - Akram Abouie Mehrizi
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran, Pasteur Avenue, P.O. Box 1316943551, Tehran, Iran
| | - Navid Dinparast Djadid
- Malaria and Vector Research Group (MVRG), Biotechnology Research Center (BRC), Pasteur Institute of Iran, Tehran, Iran, Pasteur Avenue, P.O. Box 1316943551, Tehran, Iran
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Novel Immunoinformatics Approaches to Design Multi-epitope Subunit Vaccine for Malaria by Investigating Anopheles Salivary Protein. Sci Rep 2018; 8:1125. [PMID: 29348555 PMCID: PMC5773588 DOI: 10.1038/s41598-018-19456-1] [Citation(s) in RCA: 152] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 01/02/2018] [Indexed: 12/19/2022] Open
Abstract
Malaria fever has been pervasive for quite a while in tropical developing regions causing high morbidity and mortality. The causal organism is a protozoan parasite of genus Plasmodium which spreads to the human host by the bite of hitherto infected female Anopheles mosquito. In the course of biting, a salivary protein of Anopheles helps in blood feeding behavior and having the ability to elicit the host immune response. This study represents a series of immunoinformatics approaches to design multi-epitope subunit vaccine using Anopheles mosquito salivary proteins. Designed subunit vaccine was evaluated for its immunogenicity, allergenicity and physiochemical parameters. To enhance the stability of vaccine protein, disulfide engineering was performed in a region of high mobility. Codon adaptation and in silico cloning was also performed to ensure the higher expression of designed subunit vaccine in E. coli K12 expression system. Finally, molecular docking and simulation study was performed for the vaccine protein and TLR-4 receptor, to determine the binding free energy and complex stability. Moreover, the designed subunit vaccine was found to induce anti-salivary immunity which may have the ability to prevent the entry of Plasmodium sporozoites into the human host.
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Modeling the effect of boost timing in murine irradiated sporozoite prime-boost vaccines. PLoS One 2018; 13:e0190940. [PMID: 29329308 PMCID: PMC5766151 DOI: 10.1371/journal.pone.0190940] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/22/2017] [Indexed: 11/29/2022] Open
Abstract
Vaccination with radiation-attenuated sporozoites has been shown to induce CD8+ T cell-mediated protection against pre-erythrocytic stages of malaria. Empirical evidence suggests that successive inoculations often improve the efficacy of this type of vaccines. An initial dose (prime) triggers a specific cellular response, and subsequent inoculations (boost) amplify this response to create a robust CD8+ T cell memory. In this work we propose a model to analyze the effect of T cell dynamics on the performance of prime-boost vaccines. This model suggests that boost doses and timings should be selected according to the T cell response elicited by priming. Specifically, boosting during late stages of clonal contraction would maximize T cell memory production for vaccines using lower doses of irradiated sporozoites. In contrast, single-dose inoculations would be indicated for higher vaccine doses. Experimental data have been obtained that support theoretical predictions of the model.
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Shamriz S, Ofoghi H. Engineering the chloroplast of Chlamydomonas reinhardtii to express the recombinant PfCelTOS-Il2 antigen-adjuvant fusion protein. J Biotechnol 2018; 266:111-117. [DOI: 10.1016/j.jbiotec.2017.12.015] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Revised: 11/25/2017] [Accepted: 12/17/2017] [Indexed: 12/23/2022]
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Mensah VA, Roetynck S, Kanteh EK, Bowyer G, Ndaw A, Oko F, Bliss CM, Jagne YJ, Cortese R, Nicosia A, Roberts R, D’Alessio F, Leroy O, Faye B, Kampmann B, Cisse B, Bojang K, Gerry S, Viebig NK, Lawrie AM, Clarke E, Imoukhuede EB, Ewer KJ, Hill AVS, Afolabi MO. Safety and Immunogenicity of Malaria Vectored Vaccines Given with Routine Expanded Program on Immunization Vaccines in Gambian Infants and Neonates: A Randomized Controlled Trial. Front Immunol 2017; 8:1551. [PMID: 29213269 PMCID: PMC5702785 DOI: 10.3389/fimmu.2017.01551] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Accepted: 10/31/2017] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND Heterologous prime-boost vaccination with chimpanzee adenovirus 63 (ChAd63) and modified vaccinia virus Ankara (MVA) encoding multiple epitope string thrombospondin-related adhesion protein (ME-TRAP) has shown acceptable safety and promising immunogenicity in African adult and pediatric populations. If licensed, this vaccine could be given to infants receiving routine childhood immunizations. We therefore evaluated responses to ChAd63 MVA ME-TRAP when co-administered with routine Expanded Program on Immunization (EPI) vaccines. METHODS We enrolled 65 Gambian infants and neonates, aged 16, 8, or 1 week at first vaccination and randomized them to receive either ME-TRAP and EPI vaccines or EPI vaccines only. Safety was assessed by the description of vaccine-related adverse events (AEs). Immunogenicity was evaluated using IFNγ enzyme-linked immunospot, whole-blood flow cytometry, and anti-TRAP IgG ELISA. Serology was performed to confirm all infants achieved protective titers to EPI vaccines. RESULTS The vaccines were well tolerated in all age groups with no vaccine-related serious AEs. High-level TRAP-specific IgG and T cell responses were generated after boosting with MVA. CD8+ T cell responses, previously found to correlate with protection, were induced in all groups. Antibody responses to EPI vaccines were not altered significantly. CONCLUSION Malaria vectored prime-boost vaccines co-administered with routine childhood immunizations were well tolerated. Potent humoral and cellular immunity induced by ChAd63 MVA ME-TRAP did not reduce the immunogenicity of co-administered EPI vaccines, supporting further evaluation of this regimen in infant populations. CLINICAL TRIAL REGISTRATION The clinical trial was registered on http://Clinicaltrials.gov (NCT02083887) and the Pan-African Clinical Trials Registry (PACTR201402000749217).
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Affiliation(s)
| | | | | | - Georgina Bowyer
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Amy Ndaw
- Université Cheikh Anta Diop, Dakar, Senegal
| | - Francis Oko
- Medical Research Council Unit, Fajara, Gambia
| | - Carly M. Bliss
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | | | | | - Alfredo Nicosia
- ReiThera, Rome, Italy
- CEINGE, Naples, Italy
- Department of Molecular Medicine and Medical Biotechnology, University Federico II, Naples, Italy
| | - Rachel Roberts
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Flavia D’Alessio
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Heidelberg, Germany
| | - Odile Leroy
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Heidelberg, Germany
| | | | - Beate Kampmann
- Medical Research Council Unit, Fajara, Gambia
- Centre for International Child Health, Imperial College London, London, United Kingdom
| | | | | | - Stephen Gerry
- Centre for Statistics in Medicine, Botnar Research Centre, Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences, University of Oxford, Oxford, United Kingdom
| | - Nicola K. Viebig
- European Vaccine Initiative, UniversitätsKlinikum Heidelberg, Heidelberg, Germany
| | - Alison M. Lawrie
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Ed Clarke
- Medical Research Council Unit, Fajara, Gambia
| | - Egeruan B. Imoukhuede
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
| | - Katie J. Ewer
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
| | - Adrian V. S. Hill
- The Jenner Institute Laboratories, University of Oxford, Oxford, United Kingdom
- Centre for Clinical Vaccinology and Tropical Medicine, The Jenner Institute, Churchill Hospital, Oxford, United Kingdom
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In silico design of knowledge-based Plasmodium falciparum epitope ensemble vaccines. J Mol Graph Model 2017; 78:195-205. [PMID: 29100164 DOI: 10.1016/j.jmgm.2017.10.004] [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] [Received: 07/11/2017] [Revised: 10/04/2017] [Accepted: 10/05/2017] [Indexed: 01/24/2023]
Abstract
Malaria is a global health burden, and a major cause of mortality and morbidity in Africa. Here we designed a putative malaria epitope ensemble vaccine by selecting an optimal set of pathogen epitopes. From the IEDB database, 584 experimentally-verified CD8+ epitopes and 483 experimentally-verified CD4+ epitopes were collected; 89% of which were found in 8 proteins. Using the PVS server, highly conserved epitopes were identified from variability analysis of multiple alignments of Plasmodium falciparum protein sequences. The allele-dependent binding of epitopes was then assessed using IEDB analysis tools, from which the population protection coverage of single and combined epitopes was estimated. Ten conserved epitopes from four well-studied antigens were found to have a coverage of 97.9% of the world population: 7 CD8+ T cell epitopes (LLMDCSGSI, FLIFFDLFLV, LLACAGLAYK, TPYAGEPAPF, LLACAGLAY, SLKKNSRSL, and NEVVVKEEY) and 3 CD4+ T cell epitopes (MRKLAILSVSSFLFV, KSKYKLATSVLAGLL and GLAYKFVVPGAATPYE). The addition of four heteroclitic peptides - single point mutated epitopes - increased HLA binding affinity and raised the predicted world population coverage above 99%.
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58
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Oyarzún P, Kobe B. Recombinant and epitope-based vaccines on the road to the market and implications for vaccine design and production. Hum Vaccin Immunother 2017; 12:763-7. [PMID: 26430814 DOI: 10.1080/21645515.2015.1094595] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Novel vaccination approaches based on rational design of B- and T-cell epitopes - epitope-based vaccines - are making progress in the clinical trial pipeline. The epitope-focused recombinant protein-based malaria vaccine (termed RTS,S) is a next-generation approach that successfully reached phase-III trials, and will potentially become the first commercial vaccine against a human parasitic disease. Progress made on methods such as recombinant DNA technology, advanced cell-culture techniques, immunoinformatics and rational design of immunogens are driving the development of these novel concepts. Synthetic recombinant proteins comprising both B- and T-cell epitopes can be efficiently produced through modern biotechnology and bioprocessing methods, and can enable the induction of large repertoires of immune specificities. In particular, the inclusion of appropriate CD4+ T-cell epitopes is increasingly considered a key vaccine component to elicit robust immune responses, as suggested by results coming from HIV-1 clinical trials. In silico strategies for vaccine design are under active development to address genetic variation in pathogens and several broadly protective "universal" influenza and HIV-1 vaccines are currently at different stages of clinical trials. Other methods focus on improving population coverage in target populations by rationally considering specificity and prevalence of the HLA proteins, though a proof-of-concept in humans has not been demonstrated yet. Overall, we expect immunoinformatics and bioprocessing methods to become a central part of the next-generation epitope-based vaccine development and production process.
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Affiliation(s)
- Patricio Oyarzún
- a Biotechnology Center, Facultad de Ingeniería y Tecnología, Universidad San Sebastián , Concepción , Chile
| | - Bostjan Kobe
- b School of Chemistry and Molecular Biosciences, Institute for Molecular Bioscience and Australian Infectious Diseases Research Center, University of Queensland , Brisbane , Australia
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Development of a self-assembling protein nanoparticle vaccine targeting Plasmodium falciparum Circumsporozoite Protein delivered in three Army Liposome Formulation adjuvants. Vaccine 2017; 35:5448-5454. [DOI: 10.1016/j.vaccine.2017.02.040] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2016] [Revised: 02/09/2017] [Accepted: 02/10/2017] [Indexed: 01/02/2023]
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Lim YB, Nai MH, Cao J, Loh KP, Lim CT. Graphene oxide inhibits malaria parasite invasion and delays parasitic growth in vitro. NANOSCALE 2017; 9:14065-14073. [PMID: 28901366 DOI: 10.1039/c7nr06007f] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The interactions between graphene oxide (GO) and various biological entities have been actively investigated in recent years, resulting in numerous potential bioapplications of these nanomaterials. Despite this, the biological interactions between GO and disease-causing protozoan parasites have not been well elucidated and remain relatively unexplored. Here, we investigate the in vitro interactions between GO nanosheets and a particular species of malaria parasites, Plasmodium falciparum (P. falciparum). We hypothesize that GO nanosheets may exhibit antimalarial characteristic via action mechanisms of physical obstruction of P. falciparum parasites as well as nutrient depletion. To ascertain this, we characterize the physical interactions between GO nanosheets, red blood cells (RBCs), and malarial parasites as well as the adsorption of several biomolecules necessary for parasitic survival and growth on GO nanosheets. Subsequent to establishing the origin of this antimalarial behavior of GO nanosheets, their efficiency in inhibiting parasite invasion is evaluated. We observe that GO nanosheets at various tested concentrations significantly inhibit the invasion of malaria parasites into RBCs. Furthermore, GO nanosheets delay parasite progression from the ring to the trophozoite stage. Overall, this study may further shed light on the graphene-parasite interactions and potentially facilitate the development of nanomaterial-based strategies for combating malaria.
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Affiliation(s)
- Ying Bena Lim
- Department of Biomedical Engineering, National University of Singapore, Singapore 117576. and Singapore-MIT Alliance for Research and Technology (SMART) Centre, Infectious Diseases IRG, Singapore 138602
| | - Mui Hoon Nai
- Mechanobiology Institute, National University of Singapore, Singapore 117411
| | - Jianshu Cao
- Singapore-MIT Alliance for Research and Technology (SMART) Centre, Infectious Diseases IRG, Singapore 138602 and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, USA 02139
| | - Kian Ping Loh
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117543 and Department of Chemistry, National University of Singapore, Singapore 117543
| | - Chwee Teck Lim
- NUS Graduate School for Integrative Sciences and Engineering, National University of Singapore, Singapore 117456 and Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore 117543 and Department of Biomedical Engineering, National University of Singapore, Singapore 117576. and Singapore-MIT Alliance for Research and Technology (SMART) Centre, Infectious Diseases IRG, Singapore 138602 and Mechanobiology Institute, National University of Singapore, Singapore 117411
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Patel P, Bharti PK, Bansal D, Raman RK, Mohapatra PK, Sehgal R, Mahanta J, Sultan AA, Singh N. Genetic diversity and antibody responses against Plasmodium falciparum vaccine candidate genes from Chhattisgarh, Central India: Implication for vaccine development. PLoS One 2017; 12:e0182674. [PMID: 28787005 PMCID: PMC5546615 DOI: 10.1371/journal.pone.0182674] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 07/21/2017] [Indexed: 11/22/2022] Open
Abstract
The genetic diversity in Plasmodium falciparum antigens is a major hurdle in developing an effective malaria vaccine. Protective efficacy of the vaccine is dependent on the polymorphic alleles of the vaccine candidate antigens. Therefore, we investigated the genetic diversity of the potential vaccine candidate antigens i.e. msp-1, msp-2, glurp, csp and pfs25 from field isolates of P.falciparum and determined the natural immune response against the synthetic peptide of these antigens. Genotyping was performed using Sanger method and size of alleles, multiplicity of infection, heterogeneity and recombination rate were analyzed. Asexual stage antigens were highly polymorphic with 55 and 50 unique alleles in msp-1 and msp-2 genes, respectively. The MOI for msp-1 and msp-2 were 1.67 and 1.28 respectively. A total 59 genotype was found in glurp gene with 8 types of amino acid repeats in the conserved part of RII repeat region. The number of NANP repeats from 40 to 44 was found among 55% samples in csp gene while pfs25 was found almost conserved with only two amino acid substitution site. The level of genetic diversity in the present study population was very similar to that from Asian countries. A higher IgG response was found in the B-cell epitopes of msp-1 and csp antigens and higher level of antibodies against csp B-cell epitope and glurp antigen were recorded with increasing age groups. Significantly, higher positive responses were observed in the csp antigen among the samples with ≥42 NANP repeats. The present finding showed extensive diversity in the asexual stage antigens.
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Affiliation(s)
- Priyanka Patel
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
| | - Praveen K. Bharti
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
| | - Devendra Bansal
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Qatar Foundation - Education City, Doha, Qatar
| | - Rajive K. Raman
- Community Health Centre Janakpur, District Baikunthpur, Chhattisgarh, India
| | - Pradyumna K. Mohapatra
- Regional Medical Research Centre, NE, Indian Council of Medical Research, Dibrugarh, Assam, India
| | - Rakesh Sehgal
- Department of Parasitology, Postgraduate Institute of Medical Education and Research, Chandigarh, Punjab, India
| | - Jagadish Mahanta
- Regional Medical Research Centre, NE, Indian Council of Medical Research, Dibrugarh, Assam, India
| | - Ali A. Sultan
- Department of Microbiology and Immunology, Weill Cornell Medicine - Qatar, Cornell University, Qatar Foundation - Education City, Doha, Qatar
| | - Neeru Singh
- National Institute for Research in Tribal Health, Indian Council of Medical Research, Garha, Jabalpur, Madhya Pradesh, India
- * E-mail:
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Bushell E, Gomes AR, Sanderson T, Anar B, Girling G, Herd C, Metcalf T, Modrzynska K, Schwach F, Martin RE, Mather MW, McFadden GI, Parts L, Rutledge GG, Vaidya AB, Wengelnik K, Rayner JC, Billker O. Functional Profiling of a Plasmodium Genome Reveals an Abundance of Essential Genes. Cell 2017; 170:260-272.e8. [PMID: 28708996 PMCID: PMC5509546 DOI: 10.1016/j.cell.2017.06.030] [Citation(s) in RCA: 340] [Impact Index Per Article: 48.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Revised: 04/13/2017] [Accepted: 06/19/2017] [Indexed: 12/12/2022]
Abstract
The genomes of malaria parasites contain many genes of unknown function. To assist drug development through the identification of essential genes and pathways, we have measured competitive growth rates in mice of 2,578 barcoded Plasmodium berghei knockout mutants, representing >50% of the genome, and created a phenotype database. At a single stage of its complex life cycle, P. berghei requires two-thirds of genes for optimal growth, the highest proportion reported from any organism and a probable consequence of functional optimization necessitated by genomic reductions during the evolution of parasitism. In contrast, extreme functional redundancy has evolved among expanded gene families operating at the parasite-host interface. The level of genetic redundancy in a single-celled organism may thus reflect the degree of environmental variation it experiences. In the case of Plasmodium parasites, this helps rationalize both the relative successes of drugs and the greater difficulty of making an effective vaccine. Two-thirds of Plasmodium berghei genes contribute to normal blood stage growth The core genome of malaria parasites is highly optimized for rapid host colonization Essential parasite genes and pathways are identified for drug target prioritization Low functional redundancy reflects the constant environment encountered by a parasite
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Affiliation(s)
- Ellen Bushell
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Ana Rita Gomes
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Theo Sanderson
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Burcu Anar
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Gareth Girling
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Colin Herd
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Tom Metcalf
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Katarzyna Modrzynska
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Frank Schwach
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Rowena E Martin
- Research School of Biology, Australian National University, Canberra, Australia
| | | | - Geoffrey I McFadden
- School of Biosciences, University of Melbourne, Royal Parade, Parkville, Australia
| | - Leopold Parts
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Gavin G Rutledge
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK
| | - Akhil B Vaidya
- Drexel University College of Medicine, Philadelphia, PA, USA
| | - Kai Wengelnik
- DIMNP, CNRS, INSERM, University Montpellier, Montpellier, France
| | - Julian C Rayner
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
| | - Oliver Billker
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, UK.
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Onkoba N, Mumo RM, Ochanda H, Omwandho C, Ozwara HS, Egwang TG. Safety, immunogenicity, and cross-species protection of a plasmid DNA encoding Plasmodium falciparum SERA5 polypeptide, microbial epitopes and chemokine genes in mice and olive baboons. J Biomed Res 2017; 31:321-332. [PMID: 28808204 PMCID: PMC5548993 DOI: 10.7555/jbr.31.20160025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Accepted: 12/29/2016] [Indexed: 11/03/2022] Open
Abstract
Incorporation of biomolecular epitopes to malarial antigens should be explored in the development of strain-transcending malarial vaccines. The present study sought to determine safety, immunogenicity and cross-species efficacy ofPlasmodium falciparum serine repeat antigen 5 polypeptide co-expressed with epitopes of Bacille-Calmette Guerin (BCG), tetanus toxoid (TT) and a chemokine gene. Olive baboons and BALB/c mice were randomly assigned into vaccine and control groups. The vaccine group animals were primed and boosted twice with pIRES plasmids encoding the SERA5+ BCG+ TT alone, or with either CCL5 or CCL20 and the control group with pIRES plasmid vector backbone. Mice and baboons were challenged withP. berghei ANKA and P. knowlesi H strain parasites, respectively. Safety was determined by observing for injection sites reactogenicities, hematology and clinical chemistry. Parasitaemia and survivorship profiles were used to determine cross-species efficacy, and T cell phenotypes, Th1-, Th2-type, T-regulatory immune responses and antibody responses were assessed to determine vaccine immunogenicity. The pSeBCGTT plasmid DNA vaccines were safe and induced Th1-, Th2-type, and T-regulatory responses vaccinated animals showed enhanced CD4+ (P<0.01), CD 8+ T cells (P<0.001) activation and IgG anti-SE36 antibodies responses (P<0.001) at week 4 and 8 post vaccination compared to the control group. Vaccinated mice had a 31.45-68.69% cumulative parasite load reduction and 60% suppression in baboons (P<0.05) and enhanced survivorship (P<0.001) with no clinical signs of malaria compared to the control group. The results showed that the vaccines were safe, immunogenic and conferred partial cross-species protection.
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Affiliation(s)
- Nyamongo Onkoba
- . Department of Tropical & Infectious Diseases, Institute of Primate Research, Nairobi P. O. Box 24481-00502, Kenya
- . School of Biological Sciences, University of Nairobi, Nairobi P. O. Box 30197-00100, Kenya
| | - Ruth M. Mumo
- . Department of Tropical & Infectious Diseases, Institute of Primate Research, Nairobi P. O. Box 24481-00502, Kenya
- . Department of Biochemistry, School of Medicine, University of Nairobi, Nairobi P. O. Box 30197-00100, Kenya
| | - Horace Ochanda
- . School of Biological Sciences, University of Nairobi, Nairobi P. O. Box 30197-00100, Kenya
| | - Charles Omwandho
- . Department of Biochemistry, School of Medicine, University of Nairobi, Nairobi P. O. Box 30197-00100, Kenya
- . Kirinyaga University College, Kerugoya P. O. Box 143-10300, Kenya
| | - Hastings S. Ozwara
- . Department of Tropical & Infectious Diseases, Institute of Primate Research, Nairobi P. O. Box 24481-00502, Kenya
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Identification of Protective B-Cell Epitopes within the Novel Malaria Vaccine Candidate Plasmodium falciparum Schizont Egress Antigen 1. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00068-17. [PMID: 28468980 DOI: 10.1128/cvi.00068-17] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Accepted: 04/16/2017] [Indexed: 02/03/2023]
Abstract
Naturally acquired antibodies to Plasmodium falciparum schizont egress antigen 1 (PfSEA-1A) are associated with protection against severe malaria in children. Vaccination of mice with SEA-1A from Plasmodium berghei (PbSEA-1A) decreases parasitemia and prolongs survival following P. berghei ANKA challenge. To enhance the immunogenicity of PfSEA-1A, we identified five linear B-cell epitopes using peptide microarrays probed with antisera from nonhuman primates vaccinated with recombinant PfSEA-1A (rPfSEA-1A). We evaluated the relationship between epitope-specific antibody levels and protection from parasitemia in a longitudinal treatment-reinfection cohort in western Kenya. Antibodies to three epitopes were associated with 16 to 17% decreased parasitemia over an 18-week high transmission season. We are currently designing immunogens to enhance antibody responses to these three epitopes.
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Development of a Novel Virus-Like Particle Vaccine Platform That Mimics the Immature Form of Alphavirus. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2017; 24:CVI.00090-17. [PMID: 28515133 PMCID: PMC5498722 DOI: 10.1128/cvi.00090-17] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2017] [Accepted: 05/04/2017] [Indexed: 12/27/2022]
Abstract
Virus-like particles (VLPs) are noninfectious multiprotein structures that are engineered to self-assemble from viral structural proteins. Here, we developed a novel VLP-based vaccine platform utilizing VLPs from the chikungunya virus. We identified two regions within the envelope protein, a structural component of chikungunya, where foreign antigens can be inserted without compromising VLP structure. Our VLP displays 480 copious copies of an inserted antigen on the VLP surface in a highly symmetric manner and is thus capable of inducing strong immune responses against any inserted antigen. Furthermore, by mimicking the structure of the immature form of the virus, we altered our VLP's in vivo dynamics and enhanced its immunogenicity. We used the circumsporozoite protein (CSP) of the Plasmodium falciparum malaria parasite as an antigen and demonstrated that our VLP-based vaccine elicits strong immune responses against CSP in animals. The sera from immunized monkeys protected mice from malaria infection. Likewise, mice vaccinated with P. yoelii CSP-containing VLPs were protected from an infectious sporozoite challenge. Hence, our uniquely engineered VLP platform can serve as a blueprint for the development of vaccines against other pathogens and diseases.
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66
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Matuschewski K. Vaccines against malaria-still a long way to go. FEBS J 2017; 284:2560-2568. [DOI: 10.1111/febs.14107] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/09/2017] [Accepted: 05/10/2017] [Indexed: 11/30/2022]
Affiliation(s)
- Kai Matuschewski
- Department of Molecular Parasitology; Institute of Biology; Humboldt University Berlin; Germany
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67
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Li X, Huang J, Kaneko I, Zhang M, Iwanaga S, Yuda M, Tsuji M. A potent adjuvant effect of a CD1d-binding NKT cell ligand in human immune system mice. Expert Rev Vaccines 2017; 16:73-80. [PMID: 27801602 PMCID: PMC5526659 DOI: 10.1080/14760584.2017.1256208] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Accepted: 10/31/2016] [Indexed: 10/20/2022]
Abstract
OBJECTIVES A CD1d-binding invariant natural killer T (iNKT)-cell stimulatory glycolipid, namely 7DW8-5, is shown to enhance the efficacy of radiation-attenuated sporozoites (RAS)-based malaria vaccine in mice. In the current study, we aim to determine whether 7DW8-5 can display a potent adjuvant effect in human immune system (HIS) mice. METHODS HIS-A2/hCD1d mice, which possess both functional human iNKT cells and CD8+ T cells, were generated by the transduction of NSG mice with adeno-associated virus serotype 9 expressing genes that encode human CD1d molecules and HLA-A*0201, followed by the engraftment of human hematopoietic stem cells. The magnitudes of human iNKT-cell response against 7DW8-5 and HLA-A*0201-restricted human CD8+ T-cell response against a human malaria antigen in HIS-A2/hCD1d mice were determined by using human CD1d tetramer and human HLA-A*0201 tetramer, respectively. RESULTS We found that 7DW8-5 stimulates human iNKT cells in HIS-A2/hCD1d mice, as well as those derived from HIS-A2/hCD1d mice in vitro. We also found that 7DW8-5 significantly increases the level of a human malarial antigen-specific HLA-A*0201-restricted human CD8+ T-cell response in HIS-A2/hCD1d mice. CONCLUSIONS Our study indicates that 7DW8-5 can display a potent adjuvant effect on RAS vaccine-induced anti-malarial immunity by augmenting malaria-specific human CD8+ T-cell response.
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Affiliation(s)
- Xiangming Li
- a HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center , Affiliate of The Rockefeller University , New York , NY , USA
| | - Jing Huang
- a HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center , Affiliate of The Rockefeller University , New York , NY , USA
| | - Izumi Kaneko
- b Department of Medical Zoology , Mie University Graduate School of Medicine , Tsu , Mie , Japan
| | - Min Zhang
- a HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center , Affiliate of The Rockefeller University , New York , NY , USA
- c Department of Pathology , New York University School of Medicine , New York , NY , USA
| | - Shiroh Iwanaga
- b Department of Medical Zoology , Mie University Graduate School of Medicine , Tsu , Mie , Japan
| | - Masao Yuda
- b Department of Medical Zoology , Mie University Graduate School of Medicine , Tsu , Mie , Japan
| | - Moriya Tsuji
- a HIV and Malaria Vaccine Program, Aaron Diamond AIDS Research Center , Affiliate of The Rockefeller University , New York , NY , USA
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Jimah JR, Salinas ND, Sala-Rabanal M, Jones NG, Sibley LD, Nichols CG, Schlesinger PH, Tolia NH. Malaria parasite CelTOS targets the inner leaflet of cell membranes for pore-dependent disruption. eLife 2016; 5. [PMID: 27906127 PMCID: PMC5132341 DOI: 10.7554/elife.20621] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 11/14/2016] [Indexed: 01/02/2023] Open
Abstract
Apicomplexan parasites contain a conserved protein CelTOS that, in malaria parasites, is essential for traversal of cells within the mammalian host and arthropod vector. However, the molecular role of CelTOS is unknown because it lacks sequence similarity to proteins of known function. Here, we determined the crystal structure of CelTOS and discovered CelTOS resembles proteins that bind to and disrupt membranes. In contrast to known membrane disruptors, CelTOS has a distinct architecture, specifically binds phosphatidic acid commonly present within the inner leaflet of plasma membranes, and potently disrupts liposomes composed of phosphatidic acid by forming pores. Microinjection of CelTOS into cells resulted in observable membrane damage. Therefore, CelTOS is unique as it achieves nearly universal inner leaflet cellular activity to enable the exit of parasites from cells during traversal. By providing novel molecular insight into cell traversal by apicomplexan parasites, our work facilitates the design of therapeutics against global pathogens.
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Affiliation(s)
- John R Jimah
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Nichole D Salinas
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Monica Sala-Rabanal
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, United States.,Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, United States
| | - Nathaniel G Jones
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - L David Sibley
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States
| | - Colin G Nichols
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, United States.,Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, United States
| | - Paul H Schlesinger
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, United States
| | - Niraj H Tolia
- Department of Molecular Microbiology, Washington University School of Medicine, Saint Louis, United States.,Department of Biochemistry and Molecular Biophysics, Washington University School of Medicine, Saint Louis, United States
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69
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Imboumy-Limoukou RK, Maghendi-Nzondo S, Kouna CL, Bounaadja L, Mbang S, Biteghe JC, Eboumbou C, Prugnolle F, Florent I, Lekana-Douki JB. Immunoglobulin response to the low polymorphic Pf113 antigen in children from Lastoursville, South-East of Gabon. Acta Trop 2016; 163:149-56. [PMID: 27523305 DOI: 10.1016/j.actatropica.2016.08.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 08/08/2016] [Accepted: 08/11/2016] [Indexed: 02/03/2023]
Abstract
Pf113 is a P. falciparum putatively GPI-anchored protein that has been so far localized at the surface of merozoites, suggesting it could interact with RBC surface during merozoite invasion. Previous studies conducted in Papua New Guinea and in Kenya have revealed that this protein is recognized by natural antibodies in individuals living in malaria-endemic areas and is associated with protective immunity in malaria, further supporting the potential of Pf113 for the development of anti-malaria vaccines. However, in Central Africa, no study on the immunogenicity of this protein has been conducted. Here, we report the characterization of the Pf113 immune response in 103 children by Enzyme-Linked Immunoabsorbent Assay (ELISA), using a recombinant form of Pf113 expressed in Escherichia coli, together with the study of the Pf113 polymorphism, after amplification and sequencing of 40 field isolates. Data showed that almost 51% of the studied individuals had positive antibody responses to the recombinant Pf113 protein, and that IgG subclass response was dominated by IgG3 (84%) followed by IgG1 (50%). Surprisingly the prevalence of IgG4 was 92%. In addition, gene analysis in field isolates from this region indicated that Pf113 was not highly polymorphic, in particular regarding high-activity binding peptides (HABPs). Our data reinforce the idea that Pf113 may be considered for inclusion in multicomponent blood-stage vaccines.
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Affiliation(s)
- Roméo Karl Imboumy-Limoukou
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon; Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Sorbonne Universités, Muséum National d'Histoire Naturelle, CNRS, CP52, 57 Rue Cuvier, 75005 Paris, France; Ecole Doctorale Régionale en Infectiologie Tropicale d'Afrique Centrale (ECODRAC), BP 876 Franceville, Gabon.
| | - Sidney Maghendi-Nzondo
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon
| | - Charlene Lady Kouna
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon
| | - Lotfi Bounaadja
- Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Sorbonne Universités, Muséum National d'Histoire Naturelle, CNRS, CP52, 57 Rue Cuvier, 75005 Paris, France
| | - Sophie Mbang
- Faculty of Medicine and Pharmaceutical Sciences, University of Douala Biological Sciences Unit, BP 2701 Douala, Cameroon
| | - Jean Claude Biteghe
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon; Ecole Doctorale Régionale en Infectiologie Tropicale d'Afrique Centrale (ECODRAC), BP 876 Franceville, Gabon
| | - Carole Eboumbou
- Faculty of Medicine and Pharmaceutical Sciences, University of Douala Biological Sciences Unit, BP 2701 Douala, Cameroon
| | - Franck Prugnolle
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon; UMR 5290 MIVEGEC (CNRS/IRD/UM), BP, 911 Avenue Agropolis BP 64501, 34394 Montpellier cedex 5, France
| | - Isabelle Florent
- Molécules de Communication et Adaptation des Microorganismes (MCAM, UMR 7245), Sorbonne Universités, Muséum National d'Histoire Naturelle, CNRS, CP52, 57 Rue Cuvier, 75005 Paris, France
| | - Jean-Bernard Lekana-Douki
- Centre International de Recherches Médicales de Franceville (CIRMF), Unité de Parasitologie Médicale (UPARAM), BP 769 Franceville, Gabon; Département de Parasitologie-Mycologie Médecine Tropicale, Faculté de Médecine, Université des Sciences de la Santé, BP 4009 Libreville, Gabon.
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70
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Noukpo MH, Damien GB, Elanga-N'Dille E, Sagna AB, Drame PM, Chaffa E, Boussari O, Corbel V, Akogbéto M, Remoue F. Operational Assessment of Long-Lasting Insecticidal Nets by Using an Anopheles Salivary Biomarker of Human-Vector Contact. Am J Trop Med Hyg 2016; 95:1376-1382. [PMID: 27928087 DOI: 10.4269/ajtmh.15-0541] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 08/19/2016] [Indexed: 01/10/2023] Open
Abstract
The widespread implementation of long-lasting insecticidal nets (LLINs) is a major intervention method for malaria control. Although the LLINs coverage increases, information available on the physical integrity (PI) of implemented LLINs is incomplete. This study aimed to validate human IgG antibody (Ab) response to Anopheles gSG6-P1 salivary peptide antigen, previously demonstrated as a pertinent biomarker of human exposure to Anopheles bites, for evaluating the PI of LLINs in field conditions. We analyzed data from 262 randomly selected children (< 5 years of age) in health districts of Benin. Anti-gSG6-P1 IgG responses were assessed and compared with the PI of LLINs that these same children slept under, and evaluated by the hole index (HI). Specific IgG levels were positively correlated to LLINs HI (r = 0.342; P < 0.0001). According to antipeptide IgG level (i.e., intensity of vector exposure), two categories of LLINs PI were defined: 1) group "HI: [0, 100]" corresponding to LLINs with "good" PI and 2) "HI > 100" corresponding to LLINs with "bad" PI. These results suggest that human Ab response to salivary peptide could be a complementary tool to help defining a standardized threshold of efficacy for LLINs under field use.
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Affiliation(s)
- Mahoutin H Noukpo
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Georgia B Damien
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Emmanuel Elanga-N'Dille
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - André B Sagna
- Institut Pierre Richet (IPR), Institut Nationale de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
| | - Papa M Drame
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Evelyne Chaffa
- Programme National de Lutte Contre le Paludisme (PNLP), Ministère de la Santé, Cotonou, Bénin
| | - Olayidé Boussari
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin
| | - Vincent Corbel
- UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin.,Department of Entomology, Faculty of Agriculture at Kamphaeng Saen, Kasetsart University, Nakhon Pathom, Thailand
| | - Martin Akogbéto
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin.,Faculté des Sciences et Techniques (FAST), Université d'Abomey Calavi (UAC), Abomey, Bénin
| | - Franck Remoue
- Centre de Recherche Entomologique de Cotonou (CREC), Cotonou, Bénin. .,UMR IRD 224-CNRS 5290-Universités Montpellier Maladies Infectieuses et Vecteurs: Ecologie, Génétique, Evolution et Contrôle (MIVEGEC), Cotonou, Bénin.,Institut Pierre Richet (IPR), Institut Nationale de la Santé Publique (INSP), Bouaké, Côte d'Ivoire
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71
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Lu X, Liu T, Zhu F, Chen L, Xu W. A whole-killed, blood-stage lysate vaccine protects against the malaria liver stage. Parasite Immunol 2016; 39. [PMID: 27635936 DOI: 10.1111/pim.12386] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Accepted: 09/12/2016] [Indexed: 11/30/2022]
Abstract
Although the attenuated sporozoite is the most efficient vaccine to prevent infection with the malaria parasite, the limitation of a source of sterile sporozoites greatly hampers its application. In this study, we found that the whole-killed, blood-stage lysate vaccine could confer protection against the blood stage as well as the liver stage. Although the protective immunity induced by the whole-organism vaccine against the blood stage is dependent on parasite-specific CD4+ T-cell responses and antibodies, in mice immunized with the whole-killed, blood-stage lysate vaccine, CD8+ , but not CD4+ effector T-cell responses greatly contributed to protection against the liver stage. Thus, our data suggested that the whole-killed, blood-stage lysate vaccine could be an alternative promising strategy to prevent malaria infection and to reduce the morbidity and mortality of patients with malaria.
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Affiliation(s)
- X Lu
- Department of Pathogenic Biology, Third Military Medical University, Chongqing, China.,Department of Microbiology, Third Military Medical University, Chongqing, China
| | - T Liu
- Department of Pathogenic Biology, Third Military Medical University, Chongqing, China
| | - F Zhu
- Department of Pathogenic Biology, Third Military Medical University, Chongqing, China
| | - L Chen
- Department of Pathogenic Biology, Third Military Medical University, Chongqing, China
| | - W Xu
- Department of Pathogenic Biology, Third Military Medical University, Chongqing, China
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Human CD8+ T cells mediate protective immunity induced by a human malaria vaccine in human immune system mice. Vaccine 2016; 34:4501-4506. [PMID: 27502569 PMCID: PMC5009892 DOI: 10.1016/j.vaccine.2016.08.006] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2015] [Revised: 06/15/2016] [Accepted: 08/01/2016] [Indexed: 11/30/2022]
Abstract
A number of studies have shown that CD8+ T cells mediate protective anti-malaria immunity in a mouse model. However, whether human CD8+ T cells play a role in protection against malaria remains unknown. We recently established human immune system (HIS) mice harboring functional human CD8+ T cells (HIS-CD8 mice) by transduction with HLA-A∗0201 and certain human cytokines using recombinant adeno-associated virus-based gene transfer technologies. These HIS-CD8 mice mount a potent, antigen-specific HLA-A∗0201-restricted human CD8+ T-cell response upon immunization with a recombinant adenovirus expressing a human malaria antigen, the Plasmodium falciparum circumsporozoite protein (PfCSP), termed AdPfCSP. In the present study, we challenged AdPfCSP-immunized HIS-CD8 mice with transgenic Plasmodium berghei sporozoites expressing full-length PfCSP and found that AdPfCSP-immunized (but not naïve) mice were protected against subsequent malaria challenge. The level of the HLA-A∗0201-restricted, PfCSP-specific human CD8+ T-cell response was closely correlated with the level of malaria protection. Furthermore, depletion of human CD8+ T cells from AdPfCSP-immunized HIS-CD8 mice almost completely abolished the anti-malaria immune response. Taken together, our data show that human CD8+ T cells mediate protective anti-malaria immunity in vivo.
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73
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Anand G, Reddy KS, Pandey AK, Mian SY, Singh H, Mittal SA, Amlabu E, Bassat Q, Mayor A, Chauhan VS, Gaur D. A novel Plasmodium falciparum rhoptry associated adhesin mediates erythrocyte invasion through the sialic-acid dependent pathway. Sci Rep 2016; 6:29185. [PMID: 27383149 PMCID: PMC4935899 DOI: 10.1038/srep29185] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 06/10/2016] [Indexed: 01/21/2023] Open
Abstract
Erythrocyte invasion by Plasmodium falciparum merozoites is central to blood-stage infection and malaria pathogenesis. This intricate process is coordinated by multiple parasite adhesins that bind erythrocyte receptors and mediate invasion through several alternate pathways. P. falciparum expresses 2700 genes during the blood-stages, of which the identity and function of many remains unknown. Here, we have identified and characterized a novel P. falciparum rhoptry associated adhesin (PfRA) that mediates erythrocyte invasion through the sialic-acid dependent pathway. PfRA appears to play a significant functional role as it is conserved across different Plasmodium species. It is localized in the rhoptries and further translocated to the merozoite surface. Both native and recombinant PfRA specifically bound erythrocytes in a sialic-acid dependent, chymotrypsin and trypsin resistant manner, which was abrogated by PfRA antibodies confirming a role in erythrocyte invasion. PfRA antibodies inhibited erythrocyte invasion and in combination with antibodies against other parasite ligands produced an additive inhibitory effect, thus validating its important role in erythrocyte invasion. We have thus identified a novel P. falciparum adhesin that binds with a sialic acid containing erythrocyte receptor. Our observations substantiate the strategy to block P. falciparum erythrocyte invasion by simultaneously targeting multiple conserved merozoite antigens involved in alternate invasion pathways.
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Affiliation(s)
- Gaurav Anand
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - K Sony Reddy
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Alok Kumar Pandey
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Syed Yusuf Mian
- Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
| | - Hina Singh
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Shivani Arora Mittal
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Emmanuel Amlabu
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Quique Bassat
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saude de Manhiça (CISM), Maputo, Mozambique
| | - Alfredo Mayor
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic - Universitat de Barcelona, Barcelona, Spain.,Centro de Investigação em Saude de Manhiça (CISM), Maputo, Mozambique
| | - Virander Singh Chauhan
- Malaria Group, International Centre for Genetic Engineering and Biotechnology (ICGEB), New Delhi, India
| | - Deepak Gaur
- Laboratory of Malaria and Vaccine Research, School of Biotechnology, Jawaharlal Nehru University, New Delhi, India
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Safety and Immunogenicity of ChAd63 and MVA ME-TRAP in West African Children and Infants. Mol Ther 2016; 24:1470-7. [PMID: 27109630 PMCID: PMC5010143 DOI: 10.1038/mt.2016.83] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Accepted: 03/23/2016] [Indexed: 02/08/2023] Open
Abstract
Malaria remains a significant global health burden and a vaccine would make a substantial contribution to malaria control. Chimpanzee Adenovirus 63 Modified Vaccinia Ankara Multiple epitope thrombospondin adhesion protein (ME-TRAP) and vaccination has shown significant efficacy against malaria sporozoite challenge in malaria-naive European volunteers and against malaria infection in Kenyan adults. Infants are the target age group for malaria vaccination; however, no studies have yet assessed T-cell responses in children and infants. We enrolled 138 Gambian and Burkinabe children in four different age-groups: 2–6 years old in The Gambia; 5–17 months old in Burkina Faso; 5–12 months old, and also 10 weeks old, in The Gambia; and evaluated the safety and immunogenicity of Chimpanzee Adenovirus 63 Modified Vaccinia Ankara ME-TRAP heterologous prime-boost immunization. The vaccines were well tolerated in all age groups with no vaccine-related serious adverse events. T-cell responses to vaccination peaked 7 days after boosting with Modified Vaccinia Ankara, with T-cell responses highest in 10 week-old infants. Heterologous prime-boost immunization with Chimpanzee Adenovirus 63 and Modified Vaccinia Ankara ME-TRAP was well tolerated in infants and children, inducing strong T-cell responses. We identify an approach that induces potent T-cell responses in infants, which may be useful for preventing other infectious diseases requiring cellular immunity.
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Favuzza P, Blaser S, Dreyer AM, Riccio G, Tamborrini M, Thoma R, Matile H, Pluschke G. Generation of Plasmodium falciparum parasite-inhibitory antibodies by immunization with recombinantly-expressed CyRPA. Malar J 2016; 15:161. [PMID: 26979066 PMCID: PMC4791974 DOI: 10.1186/s12936-016-1213-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Accepted: 03/05/2016] [Indexed: 01/08/2023] Open
Abstract
BACKGROUND The pathogenesis of malaria is primarily associated with blood-stage infection and there is strong evidence that antibodies specific for parasite blood-stage antigens can control parasitaemia. This provides a strong rationale for incorporation of asexual blood-stage antigen components into an effective multivalent malaria subunit vaccine. On the basis of available genome-wide transcriptomic and proteomic data, previously uncharacterized Plasmodium falciparum open reading frames were screened for new blood stage vaccine candidates. This has led to the identification of the cysteine-rich protective antigen (PfCyRPA), which forms together with PfRH5 and PfRipr a multiprotein complex that is crucial for erythrocyte invasion. METHODS Glycosylated and non-glycosylated variants of recombinant PfCyRPA were expressed and produced as secreted protein in mammalian cells. Adjuvanted formulations of purified PfCyRPA were tested to assess whether they can effectively elicit parasite inhibitory antibodies, and to investigate whether or not the glycosylation status affects antibody binding. For this purpose, two sets of PfCyRPA-specific mouse monoclonal antibodies (mAbs) have been raised and evaluated for functional activity. RESULTS Generated PfCyRPA-specific mAbs, irrespective of the immunogen's glycosylation status, showed substantial parasite in vitro growth-inhibitory activity due to inhibition of erythrocyte invasion by merozoites. Furthermore, passive immunization experiments in P. falciparum infected NOD-scid IL2Rγ (null) mice engrafted with human erythrocytes demonstrated potent in vivo growth-inhibitory activity of generated mAbs. CONCLUSIONS Recombinantly expressed PfCyRPA tested as adjuvanted vaccine formulations in mice elicited antibodies that significantly inhibit P. falciparum asexual blood stage parasite growth both in vitro and in vivo. These findings render PfCyRPA a promising blood-stage candidate antigen for inclusion into a multicomponent malaria subunit vaccine.
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Affiliation(s)
- Paola Favuzza
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Simon Blaser
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Anita M Dreyer
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Guy Riccio
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Marco Tamborrini
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland.,University of Basel, Basel, Switzerland
| | - Ralf Thoma
- Roche Pharmaceutical Research & Early Development, Small Molecule Research, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Hugues Matile
- Roche Pharmaceutical Research & Early Development, Small Molecule Research, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd., Basel, Switzerland
| | - Gerd Pluschke
- Medical Parasitology and Infection Biology Department, Swiss Tropical and Public Health Institute, Basel, Switzerland. .,University of Basel, Basel, Switzerland.
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76
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Dudley HJ, Goenka A, Orellana CJ, Martonosi SE. Multi-year optimization of malaria intervention: a mathematical model. Malar J 2016; 15:133. [PMID: 26931111 PMCID: PMC4774123 DOI: 10.1186/s12936-016-1182-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 02/18/2016] [Indexed: 11/18/2022] Open
Abstract
Background Malaria is a mosquito-borne, lethal disease that affects millions and kills hundreds of thousands of people each year, mostly children. There is an increasing need for models of malaria control. In this paper, a model is developed for allocating malaria interventions across geographic regions and time, subject to budget constraints, with the aim of minimizing the number of person-days of malaria infection. Methods The model considers a range of several conditions: climatic characteristics, treatment efficacy, distribution costs, and treatment coverage. An expanded susceptible-infected-recovered compartment model for the disease dynamics is coupled with an integer linear programming model for selecting the disease interventions. The model produces an intervention plan for all regions, identifying which combination of interventions, with which level of coverage, to use in each region and year in a 5-year planning horizon. Results Simulations using the model yield high-level, qualitative insights on optimal intervention policies: The optimal intervention policy is different when considering a 5-year time horizon than when considering only a single year, due to the effects that interventions have on the disease transmission dynamics. The vaccine intervention is rarely selected, except if its assumed cost is significantly lower than that predicted in the literature. Increasing the available budget causes the number of person-days of malaria infection to decrease linearly up to a point, after which the benefit of increased budget starts to taper. The optimal policy is highly dependent on assumptions about mosquito density, selecting different interventions for wet climates with high density than for dry climates with low density, and the interventions are found to be less effective at controlling malaria in the wet climates when attainable intervention coverage is 60 % or lower. However, when intervention coverage of 80 % is attainable, then malaria prevalence drops quickly in all geographic regions, even when factoring in the greater expense of the higher coverage against a constant budget. Conclusions The model provides a qualitative decision-making tool to weigh alternatives and guide malaria eradication efforts. A one-size-fits-all campaign is found not to be cost-effective; it is better to consider geographic variations and changes in malaria transmission over time when determining intervention strategies.
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Affiliation(s)
- Harry J Dudley
- University of Colorado Boulder, 526 UCB, University of Colorado, Boulder, CO, 80309-0526, USA.
| | - Abhishek Goenka
- Harvey Mudd College, 301 Platt Blvd, Claremont, CA, 91711, USA.
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Wikenheiser DJ, Ghosh D, Kennedy B, Stumhofer JS. The Costimulatory Molecule ICOS Regulates Host Th1 and Follicular Th Cell Differentiation in Response to Plasmodium chabaudi chabaudi AS Infection. JOURNAL OF IMMUNOLOGY (BALTIMORE, MD. : 1950) 2016; 196:778-91. [PMID: 26667167 PMCID: PMC4705592 DOI: 10.4049/jimmunol.1403206] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Accepted: 11/13/2015] [Indexed: 11/19/2022]
Abstract
Blood-stage Plasmodium chabaudi chabaudi AS infection requires cell- and Ab-mediated immunity to control acute and persistent infection, respectively. ICOS regulates CD4(+) T cell activation and promotes the induction of follicular Th (TFH) cells, CD4(+) T cells that support B cell affinity maturation within germinal centers (GCs), resulting in the production of high-affinity Abs. In this article, we demonstrate that, in response to P. c. chabaudi AS infection, the absence of ICOS resulted in an enhanced Th1 immune response that reduced peak parasitemia. Despite the absence of ICOS, CD4(+) T cells were capable of expressing PD-1, B cell lymphoma 6, and CXCR5 during early infection, indicating TFH development was not impaired. However, by day 21 postinfection, Icos(-/-) mice accumulated fewer splenic TFHs compared with Icos(+/+) mice, leading to substantially fewer GC B cells and a decrease in affinity, but not production, of parasite-specific isotype-switched Abs. Moreover, treatment of mice with anti-ICOS ligand Abs to modulate ICOS-ICOS ligand signaling revealed a requirement for ICOS in TFH differentiation only after day 6 postinfection. Ultimately, the quality and quantity of isotype-switched Abs produced in Icos(-/-) mice declined over time, resulting in impaired control of persistent parasitemia. Collectively, these data suggest ICOS is not required for TFH induction during P. c. chabaudi AS infection or production of isotype-switched Abs, but it is necessary for maintenance of a sustained high-affinity, protective Ab response.
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Affiliation(s)
- Daniel J Wikenheiser
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Debopam Ghosh
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Brian Kennedy
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205
| | - Jason S Stumhofer
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205
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Boes A, Reimann A, Twyman RM, Fischer R, Schillberg S, Spiegel H. A Plant-Based Transient Expression System for the Rapid Production of Malaria Vaccine Candidates. Methods Mol Biol 2016; 1404:597-619. [PMID: 27076325 DOI: 10.1007/978-1-4939-3389-1_39] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
There are currently no vaccines that provide sterile immunity against malaria. Various proteins from different stages of the Plasmodium falciparum life cycle have been evaluated as vaccine candidates, but none of them have fulfilled expectations. Therefore, combinations of key antigens from different stages of the parasites life cycle may be essential for the development of efficacious malaria vaccines. Following the identification of promising antigens using bioinformatics, proteomics, and/or immunological approaches, it is necessary to express, purify, and characterize these proteins and explore the potential of fusion constructs combining different antigens or antigen domains before committing to expensive and time-consuming clinical development. Here, using malaria vaccine candidates as an example, we describe how Agrobacterium tumefaciens-based transient expression in plants can be combined with a modular and flexible cloning strategy as a robust and versatile tool for the rapid production of candidate antigens during research and development.
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Affiliation(s)
- Alexander Boes
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Andreas Reimann
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | | | - Rainer Fischer
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
- Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074, Aachen, Germany
| | - Stefan Schillberg
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany
| | - Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, 52074, Aachen, Germany.
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Powles L, Xiang SD, Selomulya C, Plebanski M. The Use of Synthetic Carriers in Malaria Vaccine Design. Vaccines (Basel) 2015; 3:894-929. [PMID: 26529028 PMCID: PMC4693224 DOI: 10.3390/vaccines3040894] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2015] [Revised: 09/28/2015] [Accepted: 10/16/2015] [Indexed: 11/29/2022] Open
Abstract
Malaria vaccine research has been ongoing since the 1980s with limited success. However, recent improvements in our understanding of the immune responses required to combat each stage of infection will allow for intelligent design of both antigens and their associated delivery vaccine vehicles/vectors. Synthetic carriers (also known as vectors) are usually particulate and have multiple properties, which can be varied to control how an associated vaccine interacts with the host, and consequently how the immune response develops. This review comprehensively analyzes both historical and recent studies in which synthetic carriers are used to deliver malaria vaccines. Furthermore, the requirements for a synthetic carrier, such as size, charge, and surface chemistry are reviewed in order to understand the design of effective particle-based vaccines against malaria, as well as providing general insights. Synthetic carriers have the ability to alter and direct the immune response, and a better control of particle properties will facilitate improved vaccine design in the near future.
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Affiliation(s)
- Liam Powles
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.
| | - Sue D Xiang
- Department of Immunology and Pathology, Monash University, Melbourne, VIC 3004, Australia.
- Therapeutics and Regenerative Medicine Division, The Monash Institute of Medical Engineering (MIME), Monash University, Clayton, VIC 3800, Australia.
| | - Cordelia Selomulya
- Department of Chemical Engineering, Monash University, Clayton, VIC 3800, Australia.
| | - Magdalena Plebanski
- Department of Immunology and Pathology, Monash University, Melbourne, VIC 3004, Australia.
- Therapeutics and Regenerative Medicine Division, The Monash Institute of Medical Engineering (MIME), Monash University, Clayton, VIC 3800, Australia.
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A comparative study on worldwide genetic diversity and population structure analysis of Plasmodium vivax thrombospondin-related adhesive protein (PvTRAP) and its implications for the vivax vaccine design. INFECTION GENETICS AND EVOLUTION 2015; 36:410-423. [PMID: 26477931 DOI: 10.1016/j.meegid.2015.10.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/07/2015] [Accepted: 10/12/2015] [Indexed: 11/22/2022]
Abstract
Plasmodium vivax thrombospondin-related anonymous protein (PvTRAP) is a promising malaria vaccine candidate; however, it exhibits sequence heterogeneity. Therefore, to design a broadly protective vivax vaccine, it is essential to have adequate information on signatures of selection and geospatial genetic diversity of global PvTRAP. For this purpose, 50 Iranian pvtrap were sequenced and compared with related available global sequences in GenBank. The nucleotide sequence analysis of Iranian pvtrap in comparison with the Sal-1 sequence showed the occurrence of 15 SNPs, and all sites were dimorphic. In total, 12 amino acid substitutions were detected and 2 of which were novel, resulting in 10 haplotypes that 8 of them were not reported in any other geographic regions. In comparison with global population, haplotype and nucleotide diversities were lowest in South Korean populations while higher levels of diversities were observed in Thai and Brazilian P. vivax populations. All 12 amino acid replacements in ectodomain of Iranian PvTRAP were distributed in predicted either B- or T-cells epitope as well as intrinsically unstructured/disordered regions (IURs). The present results revealed that observing the relatively low-level diversity in PvTRAP protein might actually be selected by immune response. In summary, the present analysis in parallel to the limited available published data has shown that genetic diversity in the global pvtrap exhibits low-level diversity and geographic variation. These results are of practical significance for the strategic development and deployment of control measures in particular for development of PvTRAP-based malaria vaccine.
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RTS,S: Toward a first landmark on the Malaria Vaccine Technology Roadmap. Vaccine 2015; 33:7425-32. [PMID: 26431982 DOI: 10.1016/j.vaccine.2015.09.061] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2015] [Revised: 09/08/2015] [Accepted: 09/15/2015] [Indexed: 01/07/2023]
Abstract
The Malaria Vaccine Technology Roadmap calls for a 2015 landmark goal of a first-generation malaria vaccine that has protective efficacy against severe disease and death, lasting longer than one year. This review focuses on product development efforts over the last five years of RTS,S, a pre-erythrocytic, recombinant subunit, adjuvanted, candidate malaria vaccine designed with this goal of a first-generation malaria vaccine in mind. RTS,S recently completed a successful pivotal Phase III safety, efficacy and immunogenicity study. Although vaccine efficacy was found to be modest, a substantial number of cases of clinical malaria were averted over a 3-4 years period, particularly in settings of significant disease burden. European regulators have subsequently adopted a positive opinion under the Article 58 procedure for an indication of active immunization of children aged 6 weeks up to 17 months against malaria caused by Plasmodium falciparum and against hepatitis B. Further evaluations of the benefit, risk, feasibility and cost-effectiveness of RTS,S are now anticipated through policy and financing reviews at the global and national levels.
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Gupta B, Reddy BPN, Fan Q, Yan G, Sirichaisinthop J, Sattabongkot J, Escalante AA, Cui L. Molecular Evolution of PvMSP3α Block II in Plasmodium vivax from Diverse Geographic Origins. PLoS One 2015; 10:e0135396. [PMID: 26266539 PMCID: PMC4534382 DOI: 10.1371/journal.pone.0135396] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 07/21/2015] [Indexed: 11/29/2022] Open
Abstract
Block II of Plasmodium vivax merozoite surface protein 3α (PvMSP3α) is conserved and has been proposed as a potential candidate for a malaria vaccine. The present study aimed to compare sequence diversity in PvMSP3a block II at a local microgeographic scale in a village as well as from larger geographic regions (countries and worldwide). Blood samples were collected from asymptomatic carriers of P. vivax in a village at the western border of Thailand and PvMSP3α was amplified and sequenced. For population genetic analysis, 237 PvMSP3α block II sequences from eleven P. vivax endemic countries were analyzed. PvMSP3α sequences from 20 village-level samples revealed two length variant types with one type containing a large deletion in block I. In contrast, block II was relatively conserved; especially, some non-synonymous mutations were extensively shared among 11 parasite populations. However, the majority of the low-frequency synonymous variations were population specific. The conserved pattern of nucleotide diversity in block II sequences was probably due to functional/structural constraints, which were further supported by the tests of neutrality. Notably, a small region in block II that encodes a predicted B cell epitope was highly polymorphic and showed signs of balancing selection, signifying that this region might be influenced by the immune selection and may serve as a starting point for designing multi-antigen/stage epitope based vaccines against this parasite.
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Affiliation(s)
- Bhavna Gupta
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, United States of America
| | - B. P. Niranjan Reddy
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, United States of America
| | - Qi Fan
- Dalian Institute of Biotechnology, Dalian, Liaoning, China
| | - Guiyun Yan
- Program in Public Health, University of California, Irvine, CA 92697, United States of America
| | | | - Jetsumon Sattabongkot
- Mahidol Vivax Research Unit, Faculty of Tropical Medicine, Mahidol University, Bangkok, 10400 Thailand
| | - Ananias A. Escalante
- Institute for Genomics and Evolutionary Medicine, Temple University, Philadelphia, PA, United States of America
| | - Liwang Cui
- Department of Entomology, Pennsylvania State University, University Park, PA 16802, United States of America
- * E-mail:
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Singh SP, Verma V, Mishra BN. Characterization of Plasmodium falciparum Proteome at Asexual Blood Stages for Screening of Effective Vaccine Candidates: An Immunoinformatics Approach. ACTA ACUST UNITED AC 2015. [DOI: 10.4137/iii.s24755] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Malaria is a complex parasitic disease that is currently causing great concerns globally owing to the resistance to antimalarial drugs and lack of an effective vaccine. The present study involves the characterization of extracellular secretory proteins as vaccine candidates derived from proteome analysis of Plasmodium falciparum at asexual blood stages of malaria. Among the screened 32 proteins, 31 were predicted as antigens by the VaxiJen program, and 26 proteins had less than two transmembrane spanning regions predicted using the THMMM program. Moreover, 10 and 5 proteins were predicted to contain secretory signals by SignalP and TargetP, respectively. T-cell epitope prediction using MULTIPRED2 and NetCTL programs revealed that most of the predicted antigens are immunogenic and contain more than 10% supertype and 5% promiscuous epitopes of HLA-A, -B, or -DR. We anticipate that T-cell immune responses against asexual blood stages of Plasmodium are dispersed on a relatively large number of parasite antigens. This is the first report, to the best of our knowledge, offering new insights, at the proteome level, for the putative screening of effective vaccine candidates against the malaria pathogen. The findings also suggest new ways forward for the modern omics-guided vaccine target discovery using reverse vaccinology.
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Affiliation(s)
- Satarudra Prakash Singh
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, India
| | - Vishal Verma
- Amity Institute of Biotechnology, Amity University Uttar Pradesh, Lucknow Campus, Lucknow, India
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Hasan MA, Mazumder MHH, Chowdhury AS, Datta A, Khan MA. Molecular-docking study of malaria drug target enzyme transketolase in Plasmodium falciparum 3D7 portends the novel approach to its treatment. SOURCE CODE FOR BIOLOGY AND MEDICINE 2015; 10:7. [PMID: 26089981 PMCID: PMC4472393 DOI: 10.1186/s13029-015-0037-3] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/04/2014] [Accepted: 05/08/2015] [Indexed: 01/17/2023]
Abstract
BACKGROUND Malaria has been a major life threatening mosquito borne disease from long since. Unavailability of any effective vaccine and recent emergence of multi drug resistant strains of malaria pathogen Plasmodium falciparum continues to cause persistent deaths in the tropical and sub-tropical region. As a result, demands for new targets for more effective anti-malarial drugs are escalating. Transketolase is an enzyme of the pentose phosphate pathway; a novel pathway which is involved in energy generation and nucleic acid synthesis. Moreover, significant difference in homology between Plasmodium falciparum transketolase (Pftk) and human (Homo sapiens) transketolase makes it a suitable candidate for drug therapy. Our present study is aimed to predict the 3D structure of Plasmodium falciparum transketolase and design an inhibitor against it. RESULTS The primary and secondary structural features of the protein is calculated by ProtParam and SOPMA respectively which revealed the protein is composed of 43.3 % alpha helix and 33.04 % random coils along with 15.62 % extended strands, 8.04 % beta turns. The three dimensional structure of the transketolase is constructed using homology modeling tool MODELLAR utilizing several available transketolase structures as templates. The structure is then subjected to deep optimization and validated by structure validation tools PROCHECK, VERIFY 3D, ERRAT, QMEAN. The predicted model scored 0.74 for global model reliability in PROCHECK analysis, which ensures the quality of the model. According to VERIFY 3D the predicted model scored 0.77 which determines good environmental profile along with ERRAT score of 78.313 which is below 95 % rejection limit. Protein-protein and residue-residue interaction networks are generated by STRING and RING server respectively. CASTp server was used to analyze active sites and His 109, Asn 108 and His 515 are found to be more positive site to dock the substrate, in addition molecular docking simulation with Autodock vina determined the estimated free energy of molecular binding was of -6.6 kcal/mol for most favorable binding of 6'-Methyl-Thiamin Diphosphate. CONCLUSION This predicted structure of Pftk will serve first hand in the future development of effective Pftk inhibitors with potential anti-malarial activity. However, this is a preliminary study of designing an inhibitor against Plasmodium falciparum 3D7; the results await justification by in vitro and in vivo experimentations.
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Affiliation(s)
- Md. Anayet Hasan
- />Department of Genetic Engineering and Biotechnology, Faculty of Biological Sciences, University of Chittagong, Chittagong, 4331 Bangladesh
| | - Md. Habibul Hasan Mazumder
- />Department of Genetic Engineering and Biotechnology, Faculty of Biological Sciences, University of Chittagong, Chittagong, 4331 Bangladesh
| | - Afrin Sultana Chowdhury
- />Department of Genetic Engineering and Biotechnology, Faculty of Biological Sciences, University of Chittagong, Chittagong, 4331 Bangladesh
| | - Amit Datta
- />Department of Genetic Engineering and Biotechnology, Faculty of Biological Sciences, University of Chittagong, Chittagong, 4331 Bangladesh
| | - Md. Arif Khan
- />Department of Biotechnology and Genetic Engineering, Mawlana Bhashani Science and Technology University, Santosh, Tangail, 1902 Bangladesh
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Nalwoga A, Cose S, Wakeham K, Miley W, Ndibazza J, Drakeley C, Elliott A, Whitby D, Newton R. Association between malaria exposure and Kaposi's sarcoma-associated herpes virus seropositivity in Uganda. Trop Med Int Health 2015; 20:665-672. [PMID: 25611008 PMCID: PMC4390463 DOI: 10.1111/tmi.12464] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2015] [Indexed: 02/02/2023]
Abstract
OBJECTIVE Unlike other herpes viruses, Kaposi's sarcoma-associated herpes virus (KSHV) is not ubiquitous worldwide and is most prevalent in sub-Saharan Africa. The reasons for this are unclear. As part of a wider investigation of factors that facilitate transmission in Uganda, a high prevalence country, we examined the association between antimalaria antibodies and seropositivity against KSHV. METHODS Antibodies against P. falciparum merozoite surface protein (PfMSP)-1, P. falciparum apical membrane antigen (PfAMA)-1 and KSHV antigens (ORF73 and K8.1) were measured in samples from 1164 mothers and 1227 children. RESULTS Kaposi's sarcoma-associated herpes virus seroprevalence was 69% among mothers and 15% children. Among mothers, KSHV seroprevalence increased with malaria antibody titres: from 60% to 82% and from 54% to 77%, comparing those with the lowest and highest titres for PfMSP-1 and PfAMA-1, respectively (P < 0.0001). Among children, only antibodies to PfAMA-1 were significantly associated with KSHV seropositivity, (P < 0.0001). In both mothers and children, anti-ORF73 antibodies were more strongly associated with malaria antibodies than anti-K8.1 antibodies. CONCLUSION The association between malaria exposure and KSHV seropositivity suggests that malaria is a cofactor for KSHV infection or reactivation.
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Affiliation(s)
- Angela Nalwoga
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
| | - Stephen Cose
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
- London School of Hygiene & Tropical MedicineLondon, UK
| | - Katie Wakeham
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
- Institute of Cancer Sciences, University of GlasgowGlasgow, UK
| | - Wendell Miley
- Viral Oncology Section, Frederick National Laboratory for Cancer ResearchFrederick, MD, USA
| | - Juliet Ndibazza
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
| | | | - Alison Elliott
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
- London School of Hygiene & Tropical MedicineLondon, UK
| | - Denise Whitby
- Viral Oncology Section, Frederick National Laboratory for Cancer ResearchFrederick, MD, USA
| | - Robert Newton
- Medical Research Council/Uganda Virus Research InstituteEntebbe, Uganda
- University of YorkYork, UK
- International Agency for Research on CancerLyon, France
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Dent AE, Nakajima R, Liang L, Baum E, Moormann AM, Sumba PO, Vulule J, Babineau D, Randall A, Davies DH, Felgner PL, Kazura JW. Plasmodium falciparum Protein Microarray Antibody Profiles Correlate With Protection From Symptomatic Malaria in Kenya. J Infect Dis 2015; 212:1429-38. [PMID: 25883384 DOI: 10.1093/infdis/jiv224] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 03/25/2015] [Indexed: 11/12/2022] Open
Abstract
BACKGROUND Immunoglobulin G antibodies (Abs) to Plasmodium falciparum antigens have been associated with naturally acquired immunity to symptomatic malaria. METHODS We probed protein microarrays covering 824 unique P. falciparum protein features with plasma from residents of a community in Kenya monitored for 12 weeks for (re)infection and symptomatic malaria after administration of antimalarial drugs. P. falciparum proteins recognized by Abs from 88 children (aged 1-14 years) and 86 adults (aged ≥ 18 years), measured at the beginning of the observation period, were ranked by Ab signal intensity. RESULTS Abs from immune adults reacted with a total 163 of 824 P. falciparum proteins. Children gradually acquired Abs to the full repertoire of antigens recognized by adults. Abs to some antigens showed high seroconversion rates, reaching maximal levels early in childhood, whereas others did not reach adult levels until adolescence. No correlation between Ab signal intensity and time to (re)infection was observed. In contrast, Ab levels to 106 antigens were significantly higher in children who were protected from symptomatic malaria compared with those who were not. Abs to antigens predictive of protection included P. falciparum erythrocyte membrane protein 1, merozoite surface protein (MSP) 10, MSP2, liver-stage antigen 3, PF70, MSP7, and Plasmodium helical interspersed subtelomeric domain protein. CONCLUSIONS Protein microarrays may be useful in the search for malaria antigens associated with protective immunity.
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Affiliation(s)
- Arlene E Dent
- Center for Global Health and Diseases, Case Western Reserve University Rainbow Babies and Children's Hospital, Cleveland, Ohio
| | | | - Li Liang
- University of California, Irvine
| | | | - Ann M Moormann
- Center for Global Health Research, University of Massachusetts Medical School, Worcester
| | | | | | | | | | | | | | - James W Kazura
- Center for Global Health and Diseases, Case Western Reserve University
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87
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Dalai SK, Yadav N, Patidar M, Patel H, Singh AP. Liver-Stage Specific Response among Endemic Populations: Diet and Immunity. Front Immunol 2015; 6:125. [PMID: 25852693 PMCID: PMC4367437 DOI: 10.3389/fimmu.2015.00125] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 03/06/2015] [Indexed: 11/22/2022] Open
Abstract
Developing effective anti-malarial vaccine has been a challenge for long. Various factors including complex life cycle of parasite and lack of knowledge of stage specific critical antigens are some of the reasons. Moreover, inadequate understanding of the immune responses vis-à-vis sterile protection induced naturally by Plasmodia infection has further compounded the problem. It has been shown that people living in endemic areas take years to develop protective immunity to blood stage infection. But hardly anyone believes that immunity to liver-stage infection could be developed. Various experimental model studies using attenuated parasite suggest that liver-stage immunity might exist among endemic populations. This could be induced because of the attenuation of parasite in liver by various compounds present in the diet of endemic populations.
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Affiliation(s)
| | - Naveen Yadav
- Institute of Science, Nirma University , Ahmedabad , India
| | - Manoj Patidar
- Institute of Science, Nirma University , Ahmedabad , India
| | - Hardik Patel
- Institute of Science, Nirma University , Ahmedabad , India
| | - Agam Prasad Singh
- Infectious Diseases Laboratory, National Institute of Immunology , New Delhi , India
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88
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Sondén K, Doumbo S, Hammar U, Vafa Homann M, Ongoiba A, Traoré B, Bottai M, Crompton PD, Färnert A. Asymptomatic Multiclonal Plasmodium falciparum Infections Carried Through the Dry Season Predict Protection Against Subsequent Clinical Malaria. J Infect Dis 2015; 212:608-16. [PMID: 25712968 DOI: 10.1093/infdis/jiv088] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2014] [Accepted: 02/06/2015] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Immunity to the antigenically diverse parasite Plasmodium falciparum is acquired gradually after repeated exposure. Studies in areas of high malaria transmission have shown that asymptomatic individuals infected with multiclonal infections are at reduced risk of febrile malaria during follow-up. METHODS We assessed the relationship between the genetic diversity of clones in P. falciparum infections that persist through the dry season and the subsequent risk of febrile malaria in 225 individuals aged 2-25 years in Mali, where the 6-month malaria and dry seasons are sharply demarcated. Polymerase chain reaction-based genotyping of the highly polymorphic merozoite surface protein 2 gene was performed on blood samples collected at 5 cross-sectional surveys. RESULTS In an age-adjusted analysis, individuals with multiclonal P. falciparum infections before the rainy season were at reduced risk of febrile malaria, compared with individuals who were uninfected (hazard ratio [HR], 0.28; 95% confidence interval [CI], .11-.69). In contrast, there was no significant association between risk of malaria and having 1 clone at baseline (HR, 0.71; 95% CI, .36-1.40). CONCLUSIONS The results suggest that persistent multiclonal infections carried through the dry season contribute to protection against subsequent febrile malaria, possibly by maintaining protective immune responses that depend on ongoing parasite infection.
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Affiliation(s)
- Klara Sondén
- Unit of Infectious Diseases, Department of Medicine Solna
| | - Safiatou Doumbo
- Mali International Center of Excellence in Research, University of Sciences, Technique, and Technology of Bamako
| | - Ulf Hammar
- Unit of Biostatistics, Department of Epidemiology, Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | | | - Aissata Ongoiba
- Unit of Biostatistics, Department of Epidemiology, Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden Mali International Center of Excellence in Research, University of Sciences, Technique, and Technology of Bamako
| | - Boubacar Traoré
- Mali International Center of Excellence in Research, University of Sciences, Technique, and Technology of Bamako
| | - Matteo Bottai
- Unit of Biostatistics, Department of Epidemiology, Institute for Environmental Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Peter D Crompton
- Laboratory of Immunogenetics, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, Maryland
| | - Anna Färnert
- Unit of Infectious Diseases, Department of Medicine Solna
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89
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Proietti C, Doolan DL. The case for a rational genome-based vaccine against malaria. Front Microbiol 2015; 5:741. [PMID: 25657640 PMCID: PMC4302942 DOI: 10.3389/fmicb.2014.00741] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 12/06/2014] [Indexed: 12/22/2022] Open
Abstract
Historically, vaccines have been designed to mimic the immunity induced by natural exposure to the target pathogen, but this approach has not been effective for any parasitic pathogen of humans or complex pathogens that cause chronic disease in humans, such as Plasmodium. Despite intense efforts by many laboratories around the world on different aspects of Plasmodium spp. molecular and cell biology, epidemiology and immunology, progress towards the goal of an effective malaria vaccine has been disappointing. The premise of rational vaccine design is to induce the desired immune response against the key pathogen antigens or epitopes targeted by protective immune responses. We advocate that development of an optimally efficacious malaria vaccine will need to improve on nature, and that this can be accomplished by rational vaccine design facilitated by mining genomic, proteomic and transcriptomic datasets in the context of relevant biological function. In our opinion, modern genome-based rational vaccine design offers enormous potential above and beyond that of whole-organism vaccines approaches established over 200 years ago where immunity is likely suboptimal due to the many genetic and immunological host-parasite adaptations evolved to allow the Plasmodium parasite to coexist in the human host, and which are associated with logistic and regulatory hurdles for production and delivery.
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Affiliation(s)
- Carla Proietti
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute Brisbane, QLD, Australia
| | - Denise L Doolan
- Infectious Diseases Program, QIMR Berghofer Medical Research Institute Brisbane, QLD, Australia
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90
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Synergistic and antagonistic interactions between bednets and vaccines in the control of malaria. Proc Natl Acad Sci U S A 2015; 112:3014-9. [PMID: 25605894 DOI: 10.1073/pnas.1409467112] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
It is extremely likely that the malaria vaccines currently in development will be used in conjunction with treated bednets and other forms of malaria control. The interaction of different intervention methods is at present poorly understood in a disease such as malaria where immunity is more complex than for other pathogens that have been successfully controlled by vaccination. Here we develop a general mathematical model of malaria transmission to examine the interaction between vaccination and bednets. Counterintuitively, we find that the frailty of malaria immunity will potentially cause both synergistic and antagonistic interactions between vaccination and the use of bednets. We explore the conditions that create these tensions, and outline strategies that minimize their detrimental impact. Our analysis specifically considers the three leading vaccine classes currently in development: preerythrocytic (PEV), blood stage (BSV), and transmission blocking (TBV). We find that the combination of BSV with treated bednets can lead to increased morbidity with no added value in terms of elimination; the interaction is clearly antagonistic. In contrast, there is strong synergy between PEV and treated bednets that may facilitate elimination, although transient stages are likely to increase morbidity. The combination of TBV with treated bednets is synergistic, lowering both morbidity and elimination thresholds. Our results suggest that vaccines will not provide a straightforward solution to malaria control, and that future programs need to consider the synergistic and antagonistic interactions between vaccines and treated bednets.
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91
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Multiprotein complex between the GPI-anchored CyRPA with PfRH5 and PfRipr is crucial for Plasmodium falciparum erythrocyte invasion. Proc Natl Acad Sci U S A 2015; 112:1179-84. [PMID: 25583518 DOI: 10.1073/pnas.1415466112] [Citation(s) in RCA: 122] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Erythrocyte invasion by Plasmodium falciparum merozoites is a highly intricate process in which Plasmodium falciparum reticulocyte binding-like homologous protein 5 (PfRH5) is an indispensable parasite ligand that binds with its erythrocyte receptor, Basigin. PfRH5 is a leading blood-stage vaccine candidate because it exhibits limited polymorphisms and elicits potent strain-transcending parasite neutralizing antibodies. However, the mechanism by which it is anchored to the merozoite surface remains unknown because both PfRH5 and the PfRH5-interacting protein (PfRipr) lack transmembrane domains and GPI anchors. Here we have identified a conserved GPI-linked parasite protein, Cysteine-rich protective antigen (CyRPA) as an interacting partner of PfRH5-PfRipr that tethers the PfRH5/PfRipr/CyRPA multiprotein complex on the merozoite surface. CyRPA was demonstrated to be GPI-linked, localized in the micronemes, and essential for erythrocyte invasion. Specific antibodies against the three proteins successfully detected the intact complex in the parasite and coimmunoprecipitated the three interacting partners. Importantly, full-length CyRPA antibodies displayed potent strain-transcending invasion inhibition, as observed for PfRH5. CyRPA does not bind with erythrocytes, suggesting that its parasite neutralizing antibodies likely block its critical interaction with PfRH5-PfRipr, leading to a blockade of erythrocyte invasion. Further, CyRPA and PfRH5 antibody combinations produced synergistic invasion inhibition, suggesting that simultaneous blockade of the PfRH5-Basigin and PfRH5/PfRipr/CyRPA interactions produced an enhanced inhibitory effect. Our discovery of the critical interactions between PfRH5, PfRipr, and the GPI-anchored CyRPA clearly defines the components of the essential PfRH5 adhesion complex for P. falciparum erythrocyte invasion and offers it as a previously unidentified potent target for antimalarial strategies that could abrogate formation of the crucial multiprotein complex.
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92
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Spiegel H, Schinkel H, Kastilan R, Dahm P, Boes A, Scheuermayer M, Chudobová I, Maskus D, Fendel R, Schillberg S, Reimann A, Fischer R. Optimization of a multi-stage, multi-subunit malaria vaccine candidate for the production in Pichia pastoris by the identification and removal of protease cleavage sites. Biotechnol Bioeng 2014; 112:659-67. [PMID: 25335451 DOI: 10.1002/bit.25481] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Revised: 09/09/2014] [Accepted: 10/14/2014] [Indexed: 01/21/2023]
Abstract
We demonstrated the successful optimization of a recombinant multi-subunit malaria vaccine candidate protein for production in the methylotrophic yeast Pichia pastoris by the identification and subsequent removal of two protease cleavage sites. After observing protein degradation in the culture supernatant of a fed-batch fermentation, the predominant proteolytic fragment of the secreted recombinant protein was analyzed by mass spectrometry. The MS data indicated the cleavage of an amino acid sequence matching the yeast KEX2-protease consensus motif EKRE. The cleavage in this region was completely abolished by the deletion of the EKRE motif in a modified variant. This modified variant was produced, purified, and used for immunization of rabbits, inducing high antigen specific antibody titers (2 × 10(6) ). Total IgG from rabbit immune sera recognized different stages of Plasmodium falciparum parasites in immunofluorescence assays, indicating native folding of the vaccine candidate. However, the modified variant was still degraded, albeit into different fragments. Further analysis by mass spectrometry and N-terminal sequencing revealed a second cleavage site downstream of the motif PEVK. We therefore removed a 17-amino-acid stretch including the PEVK motif, resulting in the subsequent production of the full-length recombinant vaccine candidate protein without significant degradation, with a yield of 53 mg per liter culture volume. We clearly demonstrate that the proteolytic degradation of recombinant proteins by endogenous P. pastoris proteases can be prevented by the identification and removal of such cleavage sites. This strategy is particularly relevant for the production of recombinant subunit vaccines, where product yield and stability play a more important role than for the production of a stringently-defined native sequence which is necessary for most therapeutic molecules.
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Affiliation(s)
- Holger Spiegel
- Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Forckenbeckstrasse 6, Aachen, 52074, Germany.
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93
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Azcárate IG, Marín-García P, Pérez-Benavente S, Diez A, Puyet A, Bautista JM. Early and late B cell immune responses in lethal and self-cured rodent malaria. Immunobiology 2014; 220:684-91. [PMID: 25466589 DOI: 10.1016/j.imbio.2014.11.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Accepted: 11/11/2014] [Indexed: 11/25/2022]
Abstract
ICR mice have heterogeneous susceptibility to lethal Plasmodium yoelii yoelii 17XL from the first days of experimental infection as evidenced by the different parasitemia levels and clinical outcomes. This mouse model has revealed specific immune responses on peripheral blood correlating with the infection fate of the animals. To search for immune-markers linked to parasitemia we examined B lymphocytes in organs of the immune system as key effectors of rodent immunity against malaria. To determine changes in immune cellularity fostered by the different prognostic parasitemia we examined B cell subsets in low (<15%) and high (>50%) parasitized mice during the first days of the infection. In the case of surviving mice, we studied the preservation of memory immune response 500 days after the primary P. yoelii challenge. Correlating with the parasitemia level, it was observed an increase in total cellularity of spleen during the first week of infection which remained after 16 months of the infection in surviving animals. B cell subsets were also modified across the different infection fates. Subpopulation as follicular B cells and B-1 cells proportions behaved differently depending on the parasitemia kinetics. In addition, peritoneal cavity cells proliferated in response to high parasitemia. More significantly, P. yoelii -specific memory B cells remained in the spleen 500 days after the primo-infection. This study demonstrates that B cell kinetics is influenced by the different parasitemia courses which are naturally developed within a same strain of untreated mice. We show that high levels of parasitemia at the beginning of infection promote an extremely fast and exacerbate response of several cell populations in spleen and peritoneal cavity that, in addition, do not follow the kinetics observed in peripheral blood. Furthermore, our results describe the longest persistence of memory B cells long time upon a single malaria infection in mice.
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Affiliation(s)
- Isabel G Azcárate
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Patricia Marín-García
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain; Department of Medicine and Surgery, Psychology, Preventive Medicine and Public Health and Medical Immunology and Microbiology, Faculty of Health Sciences, Rey Juan Carlos University, Alcorcón, Madrid, Spain
| | - Susana Pérez-Benavente
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Amalia Diez
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - Antonio Puyet
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain
| | - José M Bautista
- Department of Biochemistry and Molecular Biology IV and Research Institute Hospital 12 de Octubre, Universidad Complutense de Madrid, Facultad de Veterinaria, Ciudad Universitaria, 28040 Madrid, Spain.
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94
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Crompton PD, Moebius J, Portugal S, Waisberg M, Hart G, Garver LS, Miller LH, Barillas-Mury C, Pierce SK. Malaria immunity in man and mosquito: insights into unsolved mysteries of a deadly infectious disease. Annu Rev Immunol 2014; 32:157-87. [PMID: 24655294 DOI: 10.1146/annurev-immunol-032713-120220] [Citation(s) in RCA: 207] [Impact Index Per Article: 20.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Malaria is a mosquito-borne disease caused by parasites of the obligate intracellular Apicomplexa phylum the most deadly of which, Plasmodium falciparum, prevails in Africa. Malaria imposes a huge health burden on the world's most vulnerable populations, claiming the lives of nearly one million children and pregnant women each year. Although there is keen interest in eradicating malaria, we do not yet have the necessary tools to meet this challenge, including an effective malaria vaccine and adequate vector control strategies. Here we review what is known about the mechanisms at play in immune resistance to malaria in both the human and mosquito hosts at each step in the parasite's complex life cycle with a view toward developing the tools that will contribute to the prevention of disease and death and, ultimately, to the goal of malaria eradication. In so doing, we hope to inspire immunologists to participate in defeating this devastating disease.
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95
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Bijker EM, Schats R, Obiero JM, Behet MC, van Gemert GJ, van de Vegte-Bolmer M, Graumans W, van Lieshout L, Bastiaens GJH, Teelen K, Hermsen CC, Scholzen A, Visser LG, Sauerwein RW. Sporozoite immunization of human volunteers under mefloquine prophylaxis is safe, immunogenic and protective: a double-blind randomized controlled clinical trial. PLoS One 2014; 9:e112910. [PMID: 25396417 PMCID: PMC4232459 DOI: 10.1371/journal.pone.0112910] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 10/14/2014] [Indexed: 11/30/2022] Open
Abstract
Immunization of healthy volunteers with chloroquine ChemoProphylaxis and Sporozoites (CPS-CQ) efficiently and reproducibly induces dose-dependent and long-lasting protection against homologous Plasmodium falciparum challenge. Here, we studied whether chloroquine can be replaced by mefloquine, which is the only other licensed anti-malarial chemoprophylactic drug that does not affect pre-erythrocytic stages, exposure to which is considered essential for induction of protection by CPS immunization. In a double blind randomized controlled clinical trial, volunteers under either chloroquine prophylaxis (CPS-CQ, n = 5) or mefloquine prophylaxis (CPS-MQ, n = 10) received three sub-optimal CPS immunizations by bites from eight P. falciparum infected mosquitoes each, at monthly intervals. Four control volunteers received mefloquine prophylaxis and bites from uninfected mosquitoes. CPS-MQ immunization is safe and equally potent compared to CPS-CQ inducing protection in 7/10 (70%) versus 3/5 (60%) volunteers, respectively. Furthermore, specific antibody levels and cellular immune memory responses were comparable between both groups. We therefore conclude that mefloquine and chloroquine are equally effective in CPS-induced immune responses and protection. Trial Registration ClinicalTrials.gov NCT01422954
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Affiliation(s)
- Else M. Bijker
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Remko Schats
- Leiden University Medical Center, Department of Infectious Diseases, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Joshua M. Obiero
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Marije C. Behet
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Geert-Jan van Gemert
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Marga van de Vegte-Bolmer
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Wouter Graumans
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Lisette van Lieshout
- Leiden University Medical Center, Department of Medical Microbiology, PO Box 9600, 2300 RC Leiden, The Netherlands
- Leiden University Medical Center, Department of Parasitology, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Guido J. H. Bastiaens
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Karina Teelen
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Cornelus C. Hermsen
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Anja Scholzen
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Leo G. Visser
- Leiden University Medical Center, Department of Infectious Diseases, PO Box 9600, 2300 RC Leiden, The Netherlands
| | - Robert W. Sauerwein
- Radboud university medical center, Department of Medical Microbiology, PO Box 9101, 6500 HB Nijmegen, The Netherlands
- * E-mail:
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96
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Voepel N, Boes A, Edgue G, Beiss V, Kapelski S, Reimann A, Schillberg S, Pradel G, Fendel R, Scheuermayer M, Spiegel H, Fischer R. Malaria vaccine candidate antigen targeting the pre-erythrocytic stage of Plasmodium falciparum produced at high level in plants. Biotechnol J 2014; 9:1435-45. [PMID: 25200253 DOI: 10.1002/biot.201400350] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/28/2014] [Accepted: 09/05/2014] [Indexed: 01/07/2023]
Abstract
Plants have emerged as low-cost production platforms suitable for vaccines targeting poverty-related diseases. Besides functional efficacy, the stability, yield, and purification process determine the production costs of a vaccine and thereby the feasibility of plant-based production. We describe high-level plant production and functional characterization of a malaria vaccine candidate targeting the pre-erythrocytic stage of Plasmodium falciparum. CCT, a fusion protein composed of three sporozoite antigens (P. falciparum cell traversal protein for ookinetes and sporozoites [PfCelTOS], P. falciparum circumsporozoite protein [PfCSP], and P. falciparum thrombospondin-related adhesive protein [PfTRAP]), was transiently expressed by agroinfiltration in Nicotiana benthamiana leaves, accumulated to levels up to 2 mg/g fresh leaf weight (FLW), was thermostable up to 80°C and could be purified to >95% using a simple two-step procedure. Reactivity of sera from malaria semi-immune donors indicated the immunogenic conformation of the purified fusion protein consisting of PfCelTOS, PfCSP_TSR, PfTRAP_TSR domains (CCT) protein. Total IgG from the CCT-specific mouse immune sera specifically recognized P. falciparum sporozoites in immunofluorescence assays and induced up to 35% inhibition in hepatocyte invasion assays. Featuring domains from three promising sporozoite antigens with different roles (attachment and cell traversal) in the hepatocyte invasion process, CCT has the potential to elicit broader immune responses against the pre-erythrocytic stage of P. falciparum and represents an interesting new candidate, also as a component of multi-stage, multi-subunit malaria vaccine cocktails.
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Affiliation(s)
- Nadja Voepel
- Department Plant Biotechnology, Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Aachen, Germany
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97
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Kosuwin R, Putaporntip C, Tachibana H, Jongwutiwes S. Spatial variation in genetic diversity and natural selection on the thrombospondin-related adhesive protein locus of Plasmodium vivax (PvTRAP). PLoS One 2014; 9:e110463. [PMID: 25333779 PMCID: PMC4204863 DOI: 10.1371/journal.pone.0110463] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2014] [Accepted: 09/04/2014] [Indexed: 11/18/2022] Open
Abstract
Thrombospondin-related adhesive protein (TRAP) of malaria parasites is essential for sporozoite motility and invasions into mosquito’s salivary gland and vertebrate’s hepatocyte; thereby, it is a promising target for pre-erythrocytic vaccine. TRAP of Plasmodium vivax (PvTRAP) exhibits sequence heterogeneity among isolates, an issue relevant to vaccine development. To gain insights into variation in the complete PvTRAP sequences of parasites in Thailand, 114 vivax malaria patients were recruited in 2006–2007 from 4 major endemic provinces bordering Myanmar (Tak in the northwest, n = 30 and Prachuap Khirikhan in the southwest, n = 25), Cambodia (Chanthaburi in the east, n = 29) and Malaysia (Yala and Narathiwat in the south, n = 30). In total, 26 amino acid substitutions were detected and 9 of which were novel, resulting in 44 distinct haplotypes. Haplotype and nucleotide diversities were lowest in southern P. vivax population while higher levels of diversities were observed in other populations. Evidences of positive selection on PvTRAP were demonstrated in domains II and IV and purifying selection in domains I, II and VI. Genetic differentiation was significant between each population except that between populations bordering Myanmar where transmigration was common. Regression analysis of pairwise linearized Fst and geographic distance suggests that P. vivax populations in Thailand have been isolated by distance. Sequence diversity of PvTRAP seems to be temporally stable over one decade in Tak province based on comparison of isolates collected in 1996 (n = 36) and 2006–2007. Besides natural selection, evidences of intragenic recombination have been supported in this study that could maintain and further generate diversity in this locus. It remains to be investigated whether amino acid substitutions in PvTRAP could influence host immune responses although several predicted variant T cell epitopes drastically altered the epitope scores. Knowledge on geographic diversity in PvTRAP constitutes an important basis for vaccine design provided that vaccination largely confers variant-specific immunity.
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Affiliation(s)
- Rattiporn Kosuwin
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Chaturong Putaporntip
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Hiroshi Tachibana
- Department of Infectious Diseases, Tokai University School of Medicine, Kanagawa, Japan
| | - Somchai Jongwutiwes
- Molecular Biology of Malaria and Opportunistic Parasites Research Unit, Department of Parasitology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
- * E-mail:
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Antimalarial activity of granzyme B and its targeted delivery by a granzyme B-single-chain Fv fusion protein. Antimicrob Agents Chemother 2014; 59:669-72. [PMID: 25313223 DOI: 10.1128/aac.04190-14] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
We present here the first evidence that granzyme B acts against Plasmodium falciparum (50% inhibitory concentration [IC50], 1,590 nM; 95% confidence interval [95% CI], 1,197 to 2,112 nM). We created a novel antimalarial fusion protein consisting of granzyme B fused to a merozoite surface protein 4 (MSP4)-specific single-chain Fv protein (scFv), which targets the enzyme to infected erythrocytes, with up to an 8-fold reduction in the IC50 (176 nM; 95% CI, 154 to 202 nM). This study confirms the therapeutic efficacies of recombinant antibody-mediated antimalarial immunotherapeutics based on granzyme B.
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Chaitanya RK, Sridevi P, Kumar KS, Mastan BS, Kumar KA, Dutta-Gupta A. Expression analysis of reactive oxygen species detoxifying enzyme genes in Anopheles stephensi during Plasmodium berghei midgut invasion. ASIAN PAC J TROP MED 2014. [DOI: 10.1016/s1995-7645(14)60116-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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Circumsporozoite protein-specific K(d)-restricted CD8+ T cells mediate protective antimalaria immunity in sporozoite-immunized MHC-I-K(d) transgenic mice. Mediators Inflamm 2014; 2014:728939. [PMID: 25132735 PMCID: PMC4124204 DOI: 10.1155/2014/728939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2014] [Accepted: 06/23/2014] [Indexed: 11/28/2022] Open
Abstract
Although the roles of CD8+ T cells and a major preerythrocytic antigen, the circumsporozoite (CS) protein, in contributing protective antimalaria immunity induced by radiation-attenuated sporozoites, have been shown by a number of studies, the extent to which these players contribute to antimalaria immunity is still unknown. To address this question, we have generated C57BL/6 (B6) transgenic (Tg) mice, expressing Kd molecules under the MHC-I promoter, called MHC-I-Kd-Tg mice. In this study, we first determined that a single immunizing dose of IrPySpz induced a significant level of antimalaria protective immunity in MHC-I-Kd-Tg mice but not in B6 mice. Then, by depleting various T-cell subsets in vivo, we determined that CD8+ T cells are the main mediator of the protective immunity induced by IrPySpz. Furthermore, when we immunized (MHC-I-Kd-Tg × CS-Tg) F1 mice with IrPySpz after crossing MHC-I-Kd-Tg mice with PyCS-transgenic mice (CS-Tg), which are unable to mount PyCS-specific immunity, we found that IrPySpz immunization failed to induce protective antimalaria immunity in (MHC-I-Kd-Tg × CS-Tg) F1 mice, thus indicating the absence of PyCS antigen-dependent immunity in these mice. These results indicate that protective antimalaria immunity induced by IrPySpz in MHC-I-Kd-Tg mice is mediated by CS protein-specific, Kd-restricted CD8+ T cells.
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