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Kelleher A, Zhan B, Asojo OA. Structure of monomeric Na-GST-3, a glutathione S-transferase from the major human hookworm parasite Necator americanus. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:839-43. [PMID: 23908024 PMCID: PMC3729155 DOI: 10.1107/s1744309113017661] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Accepted: 06/26/2013] [Indexed: 11/10/2022]
Abstract
Necator americanus is the major cause of human hookworm infection, which is a global cause of anemia in the developing world. Ongoing efforts to control hookworm infection include the identification of candidate vaccine antigens as well as potential therapeutic targets from the infective L3 larval stages and adult stages of the parasite. One promising family of proteins are the adult-stage-secreted cytosolic glutathione S-transferases (GSTs). Nematode GSTs facilitate the inactivation and degradation of a variety of electrophilic substrates (drugs) via the nucleophilic addition of reduced glutathione. Parasite GSTs also play significant roles in multi-drug resistance and the modulation of host immune defense mechanisms. Here, the structure of Na-GST-3, one of three GSTs secreted by adult-stage N. americanus, is reported. Unlike most GST structures, the Na-GST-3 crystal contains a monomer in the asymmetric unit. However, the monomer forms a prototypical GST dimer across the crystallographic twofold. A glutathione from the fermentation process is bound to the monomer. The overall binding cavity of Na-GST-3 is reminiscent of that of other N. americanus GSTs and is larger and capable of binding a wider array of ligands than GSTs from organisms that have other major detoxifying mechanisms. Furthermore, despite having low sequence identity to the host GST, Na-GST-3 has a greater tertiary-structure similarity to human sigma-class GST than was observed for the other N. americanus GSTs.
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Affiliation(s)
- Alan Kelleher
- Department of Pediatrics and National School of Tropical Medicine, Baylor College of Medicine, 1102 Bates Avenue BCM 320, Houston, TX 77030, USA
| | - Bin Zhan
- Department of Pediatrics and National School of Tropical Medicine, Baylor College of Medicine, 1102 Bates Avenue BCM 320, Houston, TX 77030, USA
| | - Oluwatoyin A. Asojo
- Department of Pediatrics and National School of Tropical Medicine, Baylor College of Medicine, 1102 Bates Avenue BCM 320, Houston, TX 77030, USA
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Ansell BRE, Schnyder M, Deplazes P, Korhonen PK, Young ND, Hall RS, Mangiola S, Boag PR, Hofmann A, Sternberg PW, Jex AR, Gasser RB. Insights into the immuno-molecular biology of Angiostrongylus vasorum through transcriptomics--prospects for new interventions. Biotechnol Adv 2013; 31:1486-500. [PMID: 23895945 DOI: 10.1016/j.biotechadv.2013.07.006] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2013] [Revised: 06/28/2013] [Accepted: 07/16/2013] [Indexed: 10/26/2022]
Abstract
Angiostrongylus vasorum is a metastrongyloid nematode of dogs and other canids of major clinical importance in many countries. In order to gain first insights into the molecular biology of this worm, we conducted the first large-scale exploration of its transcriptome, and predicted essential molecules linked to metabolic and biological processes as well as host immune responses. We also predicted and prioritized drug targets and drug candidates. Following Illumina sequencing (RNA-seq), 52.3 million sequence reads representing adult A. vasorum were assembled and annotated. The assembly yielded 20,033 contigs, which encoded proteins with 11,505 homologues in Caenorhabditis elegans, and additional 2252 homologues in various other parasitic helminths for which curated data sets were publicly available. Functional annotation was achieved for 11,752 (58.6%) proteins predicted for A. vasorum, including peptidases (4.5%) and peptidase inhibitors (1.6%), protein kinases (1.7%), G protein-coupled receptors (GPCRs) (1.5%) and phosphatases (1.2%). Contigs encoding excretory/secretory and immuno-modulatory proteins represented some of the most highly transcribed molecules, and encoded enzymes that digest haemoglobin were conserved between A. vasorum and other blood-feeding nematodes. Using an essentiality-based approach, drug targets, including neurotransmitter receptors, an important chemosensory ion channel and cysteine proteinase-3 were predicted in A. vasorum, as were associated small molecular inhibitors/activators. Future transcriptomic analyses of all developmental stages of A. vasorum should facilitate deep explorations of the molecular biology of this important parasitic nematode and support the sequencing of its genome. These advances will provide a foundation for exploring immuno-molecular aspects of angiostrongylosis and have the potential to underpin the discovery of new methods of intervention.
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Affiliation(s)
- Brendan R E Ansell
- Faculty of Veterinary Science, The University of Melbourne, Parkville, Victoria, Australia
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Pearson MS, Tribolet L, Cantacessi C, Periago MV, Valero MA, Valerio MA, Jariwala AR, Hotez P, Diemert D, Loukas A, Bethony J. Molecular mechanisms of hookworm disease: stealth, virulence, and vaccines. J Allergy Clin Immunol 2012; 130:13-21. [PMID: 22742835 DOI: 10.1016/j.jaci.2012.05.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2012] [Revised: 05/24/2012] [Accepted: 05/25/2012] [Indexed: 12/31/2022]
Abstract
Hookworms produce a vast repertoire of structurally and functionally diverse molecules that mediate their long-term survival and pathogenesis within a human host. Many of these molecules are secreted by the parasite, after which they interact with critical components of host biology, including processes that are key to host survival. The most important of these interactions is the hookworm's interruption of nutrient acquisition by the host through its ingestion and digestion of host blood. This results in iron deficiency and eventually the microcytic hypochromic anemia or iron deficiency anemia that is the clinical hallmark of hookworm infection. Other molecular mechanisms of hookworm infection cause a systematic suppression of the host immune response to both the parasite and to bystander antigens (eg, vaccines or allergens). This is achieved by a series of molecules that assist the parasite in the stealthy evasion of the host immune response. This review will summarize the current knowledge of the molecular mechanisms used by hookworms to survive for extended periods in the human host (up to 7 years or longer) and examine the pivotal contributions of these molecular mechanisms to chronic hookworm parasitism and host clinical outcomes.
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Affiliation(s)
- Mark S Pearson
- Center for Biodiscovery and Molecular Development of Therapeutics, James Cook University, Cairns, Australia.
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ZHAN B, SANTIAGO H, KEEGAN B, GILLESPIE P, XUE J, BETHONY J, De OLIVEIRA LM, JIANG D, DIEMERT D, XIAO SH, JONES K, FENG X, HOTEZ PJ, BOTTAZZI ME. Fusion of Na-ASP-2 with human immunoglobulin Fcγ abrogates histamine release from basophils sensitized with anti-Na-ASP-2 IgE. Parasite Immunol 2012; 34:404-11. [DOI: 10.1111/j.1365-3024.2012.01371.x] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Santiago HC, LeeVan E, Bennuru S, Ribeiro-Gomes F, Mueller E, Wilson M, Wynn T, Garboczi D, Urban J, Mitre E, Nutman TB. Molecular mimicry between cockroach and helminth glutathione S-transferases promotes cross-reactivity and cross-sensitization. J Allergy Clin Immunol 2012; 130:248-56.e9. [PMID: 22541242 PMCID: PMC3387355 DOI: 10.1016/j.jaci.2012.02.045] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 02/03/2012] [Accepted: 02/16/2012] [Indexed: 12/12/2022]
Abstract
BACKGROUND The extensive similarities between helminth proteins and allergens are thought to contribute to helminth-driven allergic sensitization. OBJECTIVE The objective of this study was to investigate the cross-reactivity between a major glutathione-S transferase allergen of cockroach (Bla g 5) and the glutathione-S transferase of Wuchereria bancrofti (WbGST), a major lymphatic filarial pathogen of humans. METHODS We compared the molecular and structural similarities between Bla g 5 and WbGST by in silico analysis and by linear epitope mapping. The levels of IgE, IgG, and IgG(4) antibodies were measured in filarial-infected and filarial-uninfected patients. Mice were infected with Heligmosomoides bakeri, and their skin was tested for cross-reactive allergic responses. RESULTS These 2 proteins are 30% identical at the amino acid level with remarkable similarity in the N-terminal region and overall structural conservation based on predicted 3-dimensional models. Filarial infection was associated with IgE, IgG, and IgG(4) anti-Bla g 5 antibody production, with a significant correlation between antibodies (irrespective of isotype) to Bla g 5 and WbGST (P< .0003). Preincubation of sera from cockroach-allergic subjects with WbGST partially depleted (by 50%-70%) anti-Bla g 5 IgE, IgG, and IgG(4) antibodies. IgE epitope mapping of Bla g 5 revealed that 2 linear N-terminal epitopes are highly conserved in WbGST corresponding to Bla g 5 peptides partially involved in the inhibition of WbGST binding. Finally, mice infected with H bakeri developed anti-HbGST IgE and showed immediate-type skin test reactivity to Bla g 5. CONCLUSION These data demonstrate that helminth glutathione-S transferase and the aeroallergen Bla g 5 share epitopes that can induce allergic cross-sensitization.
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Affiliation(s)
- Helton C Santiago
- Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, USA.
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Wang J, Tricoche N, Du L, Hunter M, Zhan B, Goud G, Didier ES, Liu J, Lu L, Marx PA, Jiang S, Lustigman S. The adjuvanticity of an O. volvulus-derived rOv-ASP-1 protein in mice using sequential vaccinations and in non-human primates. PLoS One 2012; 7:e37019. [PMID: 22615877 PMCID: PMC3355165 DOI: 10.1371/journal.pone.0037019] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2011] [Accepted: 04/12/2012] [Indexed: 12/19/2022] Open
Abstract
Adjuvants potentiate antigen-specific protective immune responses and can be key elements promoting vaccine effectiveness. We previously reported that the Onchocerca volvulus recombinant protein rOv-ASP-1 can induce activation and maturation of naïve human DCs and therefore could be used as an innate adjuvant to promote balanced Th1 and Th2 responses to bystander vaccine antigens in mice. With a few vaccine antigens, it also promoted a Th1-biased response based on pronounced induction of Th1-associated IgG2a and IgG2b antibody responses and the upregulated production of Th1 cytokines, including IL-2, IFN-γ, TNF-α and IL-6. However, because it is a protein, the rOv-ASP-1 adjuvant may also induce anti-self-antibodies. Therefore, it was important to verify that the host responses to self will not affect the adjuvanticity of rOv-ASP-1 when it is used in subsequent vaccinations with the same or different vaccine antigens. In this study, we have established rOv-ASP-1's adjuvanticity in mice during the course of two sequential vaccinations using two vaccine model systems: the receptor-binding domain (RBD) of SARS-CoV spike protein and a commercial influenza virus hemagglutinin (HA) vaccine comprised of three virus strains. Moreover, the adjuvanticity of rOv-ASP-1 was retained with an efficacy similar to that obtained when it was used for a first vaccination, even though a high level of anti-rOv-ASP-1 antibodies was present in the sera of mice before the administration of the second vaccine. To further demonstrate its utility as an adjuvant for human use, we also immunized non-human primates (NHPs) with RBD plus rOv-ASP-1 and showed that rOv-ASP-1 could induce high titres of functional and protective anti-RBD antibody responses in NHPs. Notably, the rOv-ASP-1 adjuvant did not induce high titer antibodies against self in NHPs. Thus, the present study provided a sound scientific foundation for future strategies in the development of this novel protein adjuvant.
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Affiliation(s)
- Jing Wang
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Nancy Tricoche
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Lanying Du
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Meredith Hunter
- Division of Microbiology, Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Bin Zhan
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University and the Sabin Vaccine Institute, Washington, D.C., United States of America
| | - Gaddam Goud
- Department of Microbiology, Immunology and Tropical Medicine, George Washington University and the Sabin Vaccine Institute, Washington, D.C., United States of America
| | - Elizabeth S. Didier
- Division of Microbiology, Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Jing Liu
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Lu Lu
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Preston A. Marx
- Division of Microbiology, Tulane National Primate Research Center, Covington, Louisiana, United States of America
| | - Shibo Jiang
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
| | - Sara Lustigman
- Lindsley F. Kimball Research Institute, New York Blood Center, New York, New York, United States of America
- * E-mail:
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Goud GN, Deumic V, Gupta R, Brelsford J, Zhan B, Gillespie P, Plieskatt JL, Tsao EI, Hotez PJ, Bottazzi ME. Expression, purification, and molecular analysis of the Necator americanus glutathione S-transferase 1 (Na-GST-1): a production process developed for a lead candidate recombinant hookworm vaccine antigen. Protein Expr Purif 2012; 83:145-51. [PMID: 22503665 DOI: 10.1016/j.pep.2012.03.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 03/23/2012] [Indexed: 11/18/2022]
Abstract
The enzyme Necator americanus glutathione S-transferase 1 (Na-GST-1) belongs to a unique Nu class of GSTs and is a lead candidate antigen in a bivalent human hookworm vaccine. Here we describe the expression of Na-GST-1 in the yeast Pichia pastoris at the 20 L manufacturing scale and its purification process performed by three chromatographic steps, comprised of a Q Sepharose XL anion exchange column, followed by a Butyl Sepharose HP hydrophobic affinity column and a Superdex 75 size-exclusion column. Approximately 1.5 g of recombinant protein was recovered at an overall process yield of 51%, with a purity grade of 98% and the absence of detectable host cell protein. By mass spectrometry the recombinant protein exhibits a mass of 23,676Da, which closely matches the predicted molecular mass of the protein. The expression and purification methods described here are suitable for further scale-up product development and for its use to design formulation processes suitable to generate a vaccine for clinical testing.
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Affiliation(s)
- Gaddam Narsa Goud
- Department of Microbiology, Immunology & Tropical Medicine, George Washington University Medical Center, Washington, DC, USA
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58
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Chen C, Samuel TK, Krause M, Dailey HA, Hamza I. Heme utilization in the Caenorhabditis elegans hypodermal cells is facilitated by heme-responsive gene-2. J Biol Chem 2012; 287:9601-12. [PMID: 22303006 DOI: 10.1074/jbc.m111.307694] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The roundworm Caenorhabditis elegans is a heme auxotroph that requires the coordinated actions of HRG-1 heme permeases to transport environmental heme into the intestine and HRG-3, a secreted protein, to deliver intestinal heme to other tissues including the embryo. Here we show that heme homeostasis in the extraintestinal hypodermal tissue was facilitated by the transmembrane protein HRG-2. Systemic heme deficiency up-regulated hrg-2 mRNA expression over 200-fold in the main body hypodermal syncytium, hyp 7. HRG-2 is a type I membrane protein that binds heme and localizes to the endoplasmic reticulum and apical plasma membrane. Cytochrome heme profiles are aberrant in HRG-2-deficient worms, a phenotype that was partially suppressed by heme supplementation. A heme-deficient yeast strain, ectopically expressing worm HRG-2, revealed significantly improved growth at submicromolar concentrations of exogenous heme. Taken together, our results implicate HRG-2 as a facilitator of heme utilization in the Caenorhabditis elegans hypodermis and provide a mechanism for the regulation of heme homeostasis in an extraintestinal tissue.
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Affiliation(s)
- Caiyong Chen
- Department of Animal & Avian Sciences, University of Maryland, College Park, Maryland 20742, USA
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Schneider B, Jariwala AR, Periago MV, Gazzinelli MF, Bose SN, Hotez PJ, Diemert DJ, Bethony JM. A history of hookworm vaccine development. HUMAN VACCINES 2011; 7:1234-44. [PMID: 22064562 DOI: 10.4161/hv.7.11.18443] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The human hookworms Necator americanus and Ancylostoma duodenale remain among the most common infections of humans in areas of rural poverty in the developing regions of the world, with an estimated 1 billion people infected with one or more of these parasites. Herein, we review the nearly 100 years of research, development, animal testing, and fieldwork that have led to our current progress in recombinant hookworm vaccines. We begin with the identification of hookworm at the start of the 20th century in Southern US, then discuss the progress in developed countries to eliminate human hookworm infection, and then the industrial development and field use in the 1970s a canine hookworm vaccine(Ancylostoma caninum), and finally our progress to date in the development and clinical testing of an array of recombinant antigens to prevent human hookworm disease from N. americanus infection. Special attention is given to the challenges faced in the development of a vaccine against a blood-feeding nematode, including the epidemiology of infection (high prevalence of infection), pathogenesis (chronic infection that increases with the age of the host), and a robust immune response that fails to confer the protection in the host and a concomitant absence of correlates of protection by a successful vaccine could be developed and tested. Finally, we provide the optimal and acceptable profiles of a human hookworm vaccine, including the proposed indication, target population, and route of administration, as developed by the Human Hookworm Vaccine Initiative, the only group currently working on vaccines targeting this parasite.
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Affiliation(s)
- Brent Schneider
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University Medical Center; Washington, DC USA
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Moreno Y, Gros PP, Tam M, Segura M, Valanparambil R, Geary TG, Stevenson MM. Proteomic analysis of excretory-secretory products of Heligmosomoides polygyrus assessed with next-generation sequencing transcriptomic information. PLoS Negl Trop Dis 2011; 5:e1370. [PMID: 22039562 PMCID: PMC3201918 DOI: 10.1371/journal.pntd.0001370] [Citation(s) in RCA: 73] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Accepted: 09/02/2011] [Indexed: 12/29/2022] Open
Abstract
The murine parasite Heligmosomoides polygyrus is a convenient experimental model to study immune responses and pathology associated with gastrointestinal nematode infections. The excretory-secretory products (ESP) produced by this parasite have potent immunomodulatory activity, but the protein(s) responsible has not been defined. Identification of the protein composition of ESP derived from H. polygyrus and other relevant nematode species has been hampered by the lack of genomic sequence information required for proteomic analysis based on database searches. To overcome this, a transcriptome next generation sequencing (RNA-seq) de novo assembly containing 33,641 transcripts was generated, annotated, and used to interrogate mass spectrometry (MS) data derived from 1D-SDS PAGE and LC-MS/MS analysis of ESP. Using the database generated from the 6 open reading frames deduced from the RNA-seq assembly and conventional identification programs, 209 proteins were identified in ESP including homologues of vitellogenins, retinol- and fatty acid-binding proteins, globins, and the allergen V5/Tpx-1-related family of proteins. Several potential immunomodulators, such as macrophage migration inhibitory factor, cysteine protease inhibitors, galectins, C-type lectins, peroxiredoxin, and glutathione S-transferase, were also identified. Comparative analysis of protein annotations based on the RNA-seq assembly and proteomics revealed processes and proteins that may contribute to the functional specialization of ESP, including proteins involved in signalling pathways and in nutrient transport and/or uptake. Together, these findings provide important information that will help to illuminate molecular, biochemical, and in particular immunomodulatory aspects of host-H. polygyrus biology. In addition, the methods and analyses presented here are applicable to study biochemical and molecular aspects of the host-parasite relationship in species for which sequence information is not available. Gastrointestinal (GI) nematode infections are major causes of human and animal disease. Much of their morbidity is associated with establishment of chronic infections in the host, reflecting the deployment of mechanisms to evade and modulate the immune response. The molecules responsible for these activities are poorly known. The proteins released from nematode species as excretory-secretory products (ESP) have potent immunomodulatory effects. The murine parasite Heligmosomoides bakeri (polygyrus) has served as a model to understand several aspects related to GI nematode infections. Here, we aimed to identify the protein components of H. polygyrus ESP through a proteomic approach, but the lack of genomic sequence information for this organism limited our ability to identify proteins by relying on comparisons between experimental and database-predicted mass spectra. To overcome these difficulties, we used transcriptome next-generation sequencing and several bioinformatic tools to generate and annotate a sequence assembly for this parasite. We used this information to support the protein identification process. Among the 209 proteins identified, we delineated particular processes and proteins that define the functional specialization of ESP. This work provides valuable data to establish a path to identify and understand particular parasite proteins involved in the orchestration of immune evasion events.
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Affiliation(s)
- Yovany Moreno
- Institute of Parasitology and Centre for Host Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada
| | - Pierre-Paul Gros
- Centre for the Study of Host Resistance and Centre for Host Parasite Interactions, The Research Institute of McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Mifong Tam
- Centre for the Study of Host Resistance and Centre for Host Parasite Interactions, The Research Institute of McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Mariela Segura
- Centre for the Study of Host Resistance and Centre for Host Parasite Interactions, The Research Institute of McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Rajesh Valanparambil
- Centre for the Study of Host Resistance and Centre for Host Parasite Interactions, The Research Institute of McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
| | - Timothy G. Geary
- Institute of Parasitology and Centre for Host Parasite Interactions, McGill University, Ste-Anne de Bellevue, Quebec, Canada
| | - Mary M. Stevenson
- Centre for the Study of Host Resistance and Centre for Host Parasite Interactions, The Research Institute of McGill University Health Centre and Department of Medicine, McGill University, Montreal, Quebec, Canada
- * E-mail:
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Bethony JM, Cole RN, Guo X, Kamhawi S, Lightowlers MW, Loukas A, Petri W, Reed S, Valenzuela JG, Hotez PJ. Vaccines to combat the neglected tropical diseases. Immunol Rev 2011; 239:237-70. [PMID: 21198676 DOI: 10.1111/j.1600-065x.2010.00976.x] [Citation(s) in RCA: 120] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The neglected tropical diseases (NTDs) represent a group of parasitic and related infectious diseases such as amebiasis, Chagas disease, cysticercosis, echinococcosis, hookworm, leishmaniasis, and schistosomiasis. Together, these conditions are considered the most common infections in low- and middle-income countries, where they produce a level of global disability and human suffering equivalent to better known conditions such as human immunodeficiency virus/acquired immunodeficiency syndrome and malaria. Despite their global public health importance, progress on developing vaccines for NTD pathogens has lagged because of some key technical hurdles and the fact that these infections occur almost exclusively in the world's poorest people living below the World Bank poverty line. In the absence of financial incentives for new products, the multinational pharmaceutical companies have not embarked on substantive research and development programs for the neglected tropical disease vaccines. Here, we review the current status of scientific and technical progress in the development of new neglected tropical disease vaccines, highlighting the successes that have been achieved (cysticercosis and echinococcosis) and identifying the challenges and opportunities for development of new vaccines for NTDs. Also highlighted are the contributions being made by non-profit product development partnerships that are working to overcome some of the economic challenges in vaccine manufacture, clinical testing, and global access.
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Affiliation(s)
- Jeffrey M Bethony
- Microbiology, Immunology, and Tropical Medicine, George Washington University Medical Center, Washington, DC 20037, USA.
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Jariwala AR, Oliveira LM, Diemert DJ, Keegan B, Plieskatt JL, Periago MV, Bottazzi ME, Hotez PJ, Bethony JM. Potency testing for the experimental Na-GST-1 hookworm vaccine. Expert Rev Vaccines 2011; 9:1219-30. [PMID: 20923271 DOI: 10.1586/erv.10.107] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Over the next decade, a new generation of vaccines will target the neglected tropical diseases (NTDs). The goal of most NTD vaccines will be to reduce the morbidity and decrease the chronic debilitating nature of these often-forgotten infections – outcomes that are hard to measure in the traditional potency testing paradigm. The absence of measurable correlates of protection, a lack of permissive animal models for lethal infection, and a lack of clinical indications that do not include the induction of sterilizing immunity required us to reconsider the traditional bioassay methods for determining vaccine potency. Owing to these limitations, potency assay design for NTD vaccines will increasingly rely on a paradigm where potency testing is one among many tools to ensure that a manufacturing process yields a product of consistent quality. Herein, we discuss the evolution of our thinking regarding the design of a potency assay along these newly defined lines and its application to the release of the experimental Necator americanus-glutathione-S- transferase-1 (Na-GST-1) vaccine to prevent human hookworm infection. We discuss the necessary steps to accomplish the design and implementation of such a new potency assay as a resource for the burgeoning NTD vaccine community. Our experience is that much of the existing information is proprietary and needs to be pulled together in a single source to aid in our overall understanding of potency testing.
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Jiang D, Zhan B, Mayor RS, Gillespie P, Keegan B, Bottazzi ME, Hotez P. Ac-AP-12, a novel factor Xa anticoagulant peptide from the esophageal glands of adult Ancylostoma caninum. Mol Biochem Parasitol 2011; 177:42-8. [PMID: 21251931 DOI: 10.1016/j.molbiopara.2011.01.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2010] [Revised: 01/03/2011] [Accepted: 01/06/2011] [Indexed: 10/18/2022]
Abstract
Immunoscreening an Ancylostoma caninum cDNA library with canine hookworm-infected dog serum resulted in the isolation of a 461 bp cDNA encoding Ac-AP-12, a new 9.1 kDa anticoagulant peptide (100 amino acids) with 43-69% amino acid homology to other nematode anticoagulant peptides (NAPs) from Ancylostoma hookworms. Messenger RNA transcription and expression of Ac-AP-12 was unique to the adult stage of A. caninum. The yeast expressed recombinant Ac-AP-12 demonstrated potent anticoagulant activity on human blood plasma in a concentration dependent manner, and was shown to specifically inhibit human factor Xa activity. Immunolocalization with specific rabbit antiserum showed that Ac-AP-12 was exclusively located in the esophageal glands of adult hookworm. Ac-AP-12 is hypothesized to facilitate both parasite blood feeding and digestion.
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Affiliation(s)
- Desheng Jiang
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University and the Sabin Vaccine Institute, Washington, DC 20037, USA
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Parizi LF, Utiumi KU, Imamura S, Onuma M, Ohashi K, Masuda A, da Silva Vaz I. Cross immunity with Haemaphysalis longicornis glutathione S-transferase reduces an experimental Rhipicephalus (Boophilus) microplus infestation. Exp Parasitol 2011; 127:113-8. [DOI: 10.1016/j.exppara.2010.07.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2009] [Revised: 06/29/2010] [Accepted: 07/01/2010] [Indexed: 11/15/2022]
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65
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Developing vaccines to combat hookworm infection and intestinal schistosomiasis. Nat Rev Microbiol 2010; 8:814-26. [PMID: 20948553 DOI: 10.1038/nrmicro2438] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Hookworm infection and schistosomiasis rank among the most important health problems in developing countries. Both cause anaemia and malnutrition, and schistosomiasis also results in substantial intestinal, liver and genitourinary pathology. In sub-Saharan Africa and Brazil, co-infections with the hookworm, Necator americanus, and the intestinal schistosome, Schistosoma mansoni, are common. The development of vaccines for these infections could substantially reduce the global disability associated with these helminthiases. New genomic, proteomic, immunological and X-ray crystallographic data have led to the discovery of several promising candidate vaccine antigens. Here, we describe recent progress in this field and the rationale for vaccine development.
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66
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Toh SQ, Glanfield A, Gobert GN, Jones MK. Heme and blood-feeding parasites: friends or foes? Parasit Vectors 2010; 3:108. [PMID: 21087517 PMCID: PMC2999593 DOI: 10.1186/1756-3305-3-108] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2010] [Accepted: 11/18/2010] [Indexed: 12/01/2022] Open
Abstract
Hemoparasites, like malaria and schistosomes, are constantly faced with the challenges of storing and detoxifying large quantities of heme, released from their catabolism of host erythrocytes. Heme is an essential prosthetic group that forms the reactive core of numerous hemoproteins with diverse biological functions. However, due to its reactive nature, it is also a potentially toxic molecule. Thus, the acquisition and detoxification of heme is likely to be paramount for the survival and establishment of parasitism. Understanding the underlying mechanism involved in this interaction could possibly provide potential novel targets for drug and vaccine development, and disease treatment. However, there remains a wide gap in our understanding of these mechanisms. This review summarizes the biological importance of heme for hemoparasite, and the adaptations utilized in its sequestration and detoxification.
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Affiliation(s)
- Shu Qin Toh
- Queensland Institute of Medical Research, Herston, Queensland, 4006, Australia.
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67
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Bergquist R, Lustigman S. Control of important helminthic infections vaccine development as part of the solution. ADVANCES IN PARASITOLOGY 2010; 73:297-326. [PMID: 20627146 DOI: 10.1016/s0065-308x(10)73010-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Among the tools available for the control of helminth infections, chemotherapy has come to totally dominate the field. In the veterinary field, development of drug resistance has appeared but this is not (yet) a problem in the control of human diseases. Although there is no vaccine commercially available for any human parasitic infection yet, recent progress in vaccine development is making this a future possibility for several diseases. The goal of chemotherapy is to alleviate infection and morbidity in the definitive host, or reduce transmission, while the effect of available vaccine candidates would mainly be to influence transmission through targeting the intermediate or reservoir host, when the infection is zoonotic. Apart from this general scheme, there are also vaccine candidates targeting the parasites in the definitive host, in particular the early developmental stages, which should reduce the risk of drug failure. Since the biological targets in most cases are different, vaccination would be synergistic with drug therapy. This review covers diseases caused by helminthes in both humans and animals and includes examples of diseases caused by cestodes, nematodes and trematodes. The focus is on infections for which vaccine development has been undertaken for a long time, resulting in products that could realistically become integrated into control strategies in the near future.
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Genome-wide analysis reveals novel genes essential for heme homeostasis in Caenorhabditis elegans. PLoS Genet 2010; 6:e1001044. [PMID: 20686661 PMCID: PMC2912396 DOI: 10.1371/journal.pgen.1001044] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2010] [Accepted: 06/30/2010] [Indexed: 11/23/2022] Open
Abstract
Heme is a cofactor in proteins that function in almost all sub-cellular compartments and in many diverse biological processes. Heme is produced by a conserved biosynthetic pathway that is highly regulated to prevent the accumulation of heme—a cytotoxic, hydrophobic tetrapyrrole. Caenorhabditis elegans and related parasitic nematodes do not synthesize heme, but instead require environmental heme to grow and develop. Heme homeostasis in these auxotrophs is, therefore, regulated in accordance with available dietary heme. We have capitalized on this auxotrophy in C. elegans to study gene expression changes associated with precisely controlled dietary heme concentrations. RNA was isolated from cultures containing 4, 20, or 500 µM heme; derived cDNA probes were hybridized to Affymetrix C. elegans expression arrays. We identified 288 heme-responsive genes (hrgs) that were differentially expressed under these conditions. Of these genes, 42% had putative homologs in humans, while genomes of medically relevant heme auxotrophs revealed homologs for 12% in both Trypanosoma and Leishmania and 24% in parasitic nematodes. Depletion of each of the 288 hrgs by RNA–mediated interference (RNAi) in a transgenic heme-sensor worm strain identified six genes that regulated heme homeostasis. In addition, seven membrane-spanning transporters involved in heme uptake were identified by RNAi knockdown studies using a toxic heme analog. Comparison of genes that were positive in both of the RNAi screens resulted in the identification of three genes in common that were vital for organismal heme homeostasis in C. elegans. Collectively, our results provide a catalog of genes that are essential for metazoan heme homeostasis and demonstrate the power of C. elegans as a genetic animal model to dissect the regulatory circuits which mediate heme trafficking in both vertebrate hosts and their parasites, which depend on environmental heme for survival. Heme is an iron-containing cofactor for proteins involved in many critical cellular processes. However, free heme is toxic to cells, suggesting that heme synthesis, acquisition, and transport is highly regulated. Efforts to understand heme trafficking in multicellular organisms have failed primarily due to the inability to separate the processes of endogenous heme synthesis from heme uptake and transport. Caenorhabditis elegans is unique among model organisms because it cannot synthesize heme but instead eats environmental heme to grow and develop normally. Thus, worms are an ideal genetic animal model to study heme homeostasis. This work identifies a novel list of 288 heme-responsive genes (hrgs) in C. elegans and a number of related genes in humans and medically relevant parasites. Knocking down the function of each of these hrgs reveals roles for several in heme uptake, transport, and detection within the organism. Our study provides insights into metazoan regulation of organismal heme homeostasis. The identification of parasite-specific hrg homologs may permit the selective design and screening of drugs that specifically target heme uptake pathways in parasites without affecting the host. Thus, this work has therapeutic implications for the treatment of human iron deficiency, one of the top ten mortality factors world-wide.
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Solano-Parada J, Gonzalez-Gonzalez G, Torró LMDP, dos Santos MFB, Espino AM, Burgos M, Osuna A. Effectiveness of intranasal vaccination against Angiostrongylus costaricensis using a serine/threonine phosphatase 2 A synthetic peptide and recombinant antigens. Vaccine 2010; 28:5185-96. [PMID: 20558243 DOI: 10.1016/j.vaccine.2010.05.072] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 05/20/2010] [Accepted: 05/28/2010] [Indexed: 01/26/2023]
Abstract
Intranasal immunization was assayed in C57BL/6 mice against Angiostrongylus costaricensis using a synthetic and a recombinant peptide belonging to the catalytic region of the serine/threonine phosphatase 2 A (PP2A) of the parasite. Immunization was carried out with the synthetic peptide (SP) polymerized either with itself or with the beta fraction of the cholera toxin (CTB) and then enclosed in nanocapsules of phosphatidyl choline, cholesterol and Quil A (ISCOM). Another group of mice was immunized with recombinant peptide. Immunization consisted of two intranasal inoculations at two-week intervals, and the challenge with L3 larvae was made one month after the last vaccination. The effectiveness of immunization was evaluated 30 days after infection by analysis of the number of parasites in the arteries of the immunized mice, as well as by measuring spleen sizes in the experimental groups. The response induced was determined by identifying the isotypes of IgG as well as the IgE and IgA specific antigen response. The interleukins produced by the splenocyte culture of the different groups were assessed after exposing them to the peptide used in the immunization. From our results, 60%, 80%, and 100% protection against the A. costaricensis challenge was achieved in mice immunized with polymerized synthetic peptide in ISCOM, synthetic peptide polymerized with the CTB in ISCOM and inclusion bodies respectively. Splenomegaly was found to be less evident in the immunized mice than in the controls. A significant increase in IFN gamma and IL-17 levels was observed in the group with 100% protection. The results showed that vaccination through the nasal mucosa may constitute a useful method of immunization and result in a protective immune response against A. costaricensis.
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Affiliation(s)
- J Solano-Parada
- Institute of Biotechnology, Biochemistry and Molecular Parasitology Group, University of Granada, Edif Mecenas, Campus Fuentenueva, 18071 Granada, Spain
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Molecular cloning, biochemical characterization, and partial protective immunity of the heme-binding glutathione S-transferases from the human hookworm Necator americanus. Infect Immun 2010; 78:1552-63. [PMID: 20145100 DOI: 10.1128/iai.00848-09] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Hookworm glutathione S-transferases (GSTs) are critical for parasite blood feeding and survival and represent potential targets for vaccination. Three cDNAs, each encoding a full-length GST protein from the human hookworm Necator americanus (and designated Na-GST-1, Na-GST-2, and Na-GST-3, respectively) were isolated from cDNA based on their sequence similarity to Ac-GST-1, a GST from the dog hookworm Ancylostoma caninum. The open reading frames of the three N. americanus GSTs each contain 206 amino acids with 51% to 69% sequence identity between each other and Ac-GST-1. Sequence alignment with GSTs from other organisms shows that the three Na-GSTs belong to a nematode-specific nu-class GST family. All three Na-GSTs, when expressed in Pichia pastoris, exhibited low lipid peroxidase and glutathione-conjugating enzymatic activities but high heme-binding capacities, and they may be involved in the detoxification and/or transport of heme. In two separate vaccine trials, recombinant Na-GST-1 formulated with Alhydrogel elicited 32 and 39% reductions in adult hookworm burdens (P < 0.05) following N. americanus larval challenge relative to the results for a group immunized with Alhydrogel alone. In contrast, no protection was observed in vaccine trials with Na-GST-2 or Na-GST-3. On the basis of these and other preclinical data, Na-GST-1 is under possible consideration for further vaccine development.
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71
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Rathaur S, Singh A, Yadav M, Rai R. Evidence for the presence of prostaglandin H synthase like enzyme in female Setaria cervi and its inhibition by diethylcarbamazine. Acta Trop 2009; 111:71-7. [PMID: 19426666 DOI: 10.1016/j.actatropica.2009.02.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2008] [Revised: 02/25/2009] [Accepted: 02/26/2009] [Indexed: 10/21/2022]
Abstract
Experimental evidence has shown that Setaria cervi a bovine filarial parasite contains significant amount of prostaglandin H synthase like activity in the somatic extract of its different life stages. A protein with characteristics of prostaglandin H synthase was purified to homogeneity from female somatic extract using a combination of affinity and gel filtration chromatography. Molecular weight of purified enzyme was 70kDa as determined by SDS-PAGE. Purified enzyme showed high activity with arachidonic acid and TMPD substrates suggests the presence of both cyclooxygenase and peroxidase activity in enzyme. Fluorescence spectroscopy and hemin-associated peroxidase activity confirmed presence of heme in purified enzyme. The K(m) and V(max) values using arachidonic acid were determined to be 79+/-1.5microM and 0.165+/-0.2U/ml, respectively. Further, indomethacin and aspirin, specific inhibitors for PGHS, significantly inhibited the enzyme activity. Diethylcarbamazine, an antifilarial drug inhibited the microfilarial PGHS like activity as well as their motility. Here we are reporting for the first time PGHS like activity in filarial parasite and its inhibition with DEC which provide that this enzyme could be used as a drug target.
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72
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Abstract
Oesophagostomum dentatum stages were investigated for glutathione S-transferase (GST) expression at the protein and mRNA levels. GST activity was detected in all stages (infectious and parasitic stages including third- and fourth-stage larvae of different ages as well as males and females) and could be dose-dependently inhibited with sulfobromophthalein (SBP). Addition of SBP to in vitro larval cultures reversibly inhibited development from third- to fourth-stage larvae. Two glutathione-affinity purified proteins (23 and 25 kDa) were detected in lysates of exsheathed third-stage larvae by SDS-PAGE. PCR-primers were designed based on peptide sequences and conserved GST sequences of other nematodes for complete cDNA sequences (621 and 624 nt) of 2 isoforms, Od-GST1 and Od-GST2, with 72% nucleotide similarity and 75% for the deduced proteins. Genomic sequences consisted of 7 exons and 6 introns spanning 1296 bp for Od-GST1 and 1579 and 1606 bp for Od-GST2. Quantitative real-time-PCR revealed considerably elevated levels of Od-GST1 in the early parasitic stages and slightly reduced levels of Od-GST2 in male worms. Both Od-GSTs were most similar to GST of Ancylostoma caninum (nucleotides: 73 and 70%; amino acids: 80 and 73%). The first three exons (75 amino acids) corresponded to a synthetic prostaglandin D2 synthase (53% similarity). O. dentatum GSTs might be involved in intrinsic metabolic pathways which could play a role both in nematode physiology and in host-parasite interactions.
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73
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Oliveira TMFS, Mineo TWP, Bason M, Day MJ, Machado RZ. IgG subclass profile of serum antibodies to Leishmania chagasi in naturally infected and vaccinated dogs. Vet Parasitol 2009; 162:16-22. [PMID: 19345019 DOI: 10.1016/j.vetpar.2009.02.018] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2008] [Revised: 01/16/2009] [Accepted: 02/08/2009] [Indexed: 11/19/2022]
Abstract
Leishmaniosis is a zoonotic disease that is caused by Leishmania chagasi and transmitted by sandflies. In Brazil, canine visceral leishmaniosis (CVL) is an emerging disease in urban areas and dogs are the main reservoir host. The aim of the present study was to analyze IgG seroconversion of dogs to L. chagasi and to determine whether there was dominance of any particular IgG subclasses in this immune response. Antibody detection was performed by ELISA with 120 sera from confirmed seropositive dogs (obtained from epidemiological surveys), 24 samples from naturally infected dogs with clinical signs of the disease, and 40 sera from animals immunized with a commercially available vaccine. Ninety percent of seropositive survey population samples had detectable levels of anti-Leishmania total IgG by ELISA, compared with 70% of samples from symptomatic animals and only 13% of samples from the immunized dogs. The serological response in each group displayed a distinct bias in IgG subclass usage as detected by application of a panel of monoclonal antibodies specific for canine IgG1-IgG4. The survey population, which comprised predominantly asymptomatic dogs, had a dominant IgG1 response, while symptomatic dogs had a mixed pattern of IgG subclass usage. In contrast, sera from vaccinated animals had high titres of IgG2 Leishmania antibody. These distinctive IgG subclass profiles may be related to the infection status of the dogs. Moreover, detection of antigen-specific IgG subclasses may provide a valuable diagnostic tool for predicting the clinical outcome of visceral leishmaniasis, as well as differentiating infected dogs from vaccinated animals.
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Affiliation(s)
- Trícia M F S Oliveira
- Immunoparasitology Laboratory, Department of Veterinary Pathology, FCAV/UNESP, Jaboticabal, São Paulo 14.884-900, Brazil
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Sabatelli L, Ghani AC, Rodrigues LC, Hotez PJ, Brooker S. Modelling heterogeneity and the impact of chemotherapy and vaccination against human hookworm. J R Soc Interface 2008; 5:1329-41. [PMID: 18331978 DOI: 10.1098/rsif.2007.1255] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
There is a growing emphasis on the development of vaccines against helminths (worms), and mathematical models provide a useful tool to assess the impact of new vaccines under a range of scenarios. The present study describes a stochastic individual-based model to assess the relative impact of chemotherapy and vaccination against human hookworm infection and investigates the implications of potential correlations between risk of infection and vaccine efficacy. Vaccination is simulated as a reduction in susceptibility to infection and the model includes population heterogeneities and dynamical waning of protection. To help identify appropriate measures of vaccine impact, we present a novel framework to quantify the vaccine impact on the infection-associated morbidity and introduce a measure of symmetry to study the correspondence between reduction in intensity and reduction in morbidity. Our modelling shows that, in high-transmission settings, the greatest impact of vaccination will be attained when vaccine efficacy is the greatest among individuals harbouring the heaviest worm burdens, and that the decline of morbidity primarily depends on the level of protection attained in the most at risk 8-12% of the population. We also demonstrate that if risk of infection and vaccine protection are correlated, there is not always a direct correspondence between the reduction in worm burden and in morbidity, with the precise relationship varying according to transmission setting.
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Affiliation(s)
- L Sabatelli
- London School of Hygiene and Tropical Medicine, Keppel Street, London, UK.
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75
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Ahmad R, Srivastava AK, Walter RD. Purification and biochemical characterization of cytosolic glutathione-S-transferase from filarial worms Setaria cervi. Comp Biochem Physiol B Biochem Mol Biol 2008; 151:237-45. [DOI: 10.1016/j.cbpb.2008.03.019] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2007] [Revised: 03/23/2008] [Accepted: 03/31/2008] [Indexed: 10/22/2022]
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Perally S, Lacourse EJ, Campbell AM, Brophy PM. Heme transport and detoxification in nematodes: subproteomics evidence of differential role of glutathione transferases. J Proteome Res 2008; 7:4557-65. [PMID: 18720983 DOI: 10.1021/pr800395x] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
In contrast to their mammalian hosts, parasitic nematodes are heme auxotrophs and require pathways for the uptake and transport of exogenous heme for incorporation into hemoproteins. Phase II detoxification Nu-class glutathione transferase (GST) proteins have a proposed role as heme-binding ligandins in parasitic nematodes. The genome-verified free-living nematode Caenorhabditis elegans also cannot synthesize heme and is an ideal functional genomics model to delineate the role of individual nematode GSTs in heme trafficking and heme detoxification. In this study, C. elegans was exposed to externally controlled heme concentrations ranging from 20-fold suboptimal growth levels to 10-fold supra-optimal growth levels to mimic fluctuations in blood- and tissue-feeding parasitic cousins from the same nematode group. A new heme-responsive GST (GST-19) was identified by subproteomics approaches. Functional characterization of this and two other C. elegans GSTs revealed that they all have high affinity for heme compounds similar to mammalian soluble heme carrier proteins such as HBP23 ( K d approximately 10 (-8) M). In the genomics-predicted absence of orthologous mammalian soluble heme-binding proteins in nematodes, we propose that Nu-class GSTs are candidates in the cellular processing of heme compounds. Toxic heme binding may be coupled to enzymatic protection from its breakdown as several GSTs possess glutathione peroxidase activity.
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Affiliation(s)
- Samïrah Perally
- Institute of Biological, Environmental, and Rural Sciences, Aberystwyth University, Aberystwyth, Ceredigion SY23 3DA, United Kingdom.
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77
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Abstract
Hookworm infection caused by the soil-transmitted nematodes Necator americanus and Ancylostoma duodenale is one of the most common parasitic infections worldwide. Although not directly responsible for substantial mortality, it causes significant morbidity in the form of chronic anemia and protein malnutrition. Current global control efforts based on periodic mass anthelmintic administration are unsustainable, and new control strategies must be developed. This review describes progress in the development of vaccines against hookworm infection, including the preclinical and initial clinical testing of the N. americanus Ancylostoma Secreted Protein-2 Hookworm Vaccine. Plans call for eventual development of a vaccine that will combine at least 2 hookworm antigens--one targeting the larval stage of the life cycle and another targeting the adult worm living in the gastrointestinal tract.
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Affiliation(s)
- David J Diemert
- Sabin Vaccine Institute, George Washington University, Washington, DC 20037, USA
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78
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Torres-Rivera A, Landa A. Glutathione transferases from parasites: a biochemical view. Acta Trop 2008; 105:99-112. [PMID: 17897613 DOI: 10.1016/j.actatropica.2007.08.005] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2007] [Revised: 08/11/2007] [Accepted: 08/21/2007] [Indexed: 10/22/2022]
Abstract
The glutathione transferase (GST) system of parasites represents the main detoxification mechanism of hydrophobic and electrophilic compounds. Parasites lack the CYP450 activity, hence part of its function has been taken over by other enzymes including GSTs. Cytosolic GSTs (cGSTs) are found in this system and constitute a versatile and numerous group that in parasites display many peculiarities in contrast to mammalian cGSTs. This review summarizes aspects of the biochemistry of parasite cGSTs such as substrate specificities, inhibitor sensitivities, classification, kinetics and catalysis, as well as some aspects of their protective role.
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Affiliation(s)
- Anayetzin Torres-Rivera
- Departamento de Microbiología y Parasitología, Facultad de Medicina, Universidad Nacional Autónoma de México, Edificio A, 2o Piso, Ciudad Universitaria, México D.F. 04510, Mexico
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79
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Asojo OA, Homma K, Sedlacek M, Ngamelue M, Goud GN, Zhan B, Deumic V, Asojo O, Hotez PJ. X-ray structures of Na-GST-1 and Na-GST-2 two glutathione S-transferase from the human hookworm Necator americanus. BMC STRUCTURAL BIOLOGY 2007; 7:42. [PMID: 17594497 PMCID: PMC1924862 DOI: 10.1186/1472-6807-7-42] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/09/2007] [Accepted: 06/26/2007] [Indexed: 05/16/2023]
Abstract
BACKGROUND Human hookworm infection is a major cause of anemia and malnutrition of adults and children in the developing world. As part of on-going efforts to control hookworm infection, The Human Hookworm Vaccine Initiative has identified candidate vaccine antigens from the infective L3 larval stages and adult stages of the parasite. Adult stage antigens include the cytosolic glutathione-S-transferases (GSTs). Nematode GSTs facilitate the inactivation and degradation of a variety of electrophilic substrates (drugs) via the nucleophilic addition of reduced glutathione. Parasite GSTs also play significant roles in multi-drug resistance and the modulation of host-immune defense mechanisms. RESULTS The crystal structures of Na-GST-1 and Na-GST-2, two major GSTs from Necator americanus the main human hookworm parasite, have been solved at the resolution limits of 2.4 A and 1.9 A respectively. The structure of Na-GST-1 was refined to R-factor 18.9% (R-free 28.3%) while that of Na-GST-2 was refined to R-factor 17.1% (R-free 21.7%). Glutathione usurped during the fermentation process in bound in the glutathione binding site (G-site) of each monomer of Na-GST-2. Na-GST-1 is uncomplexed and its G-site is abrogated by Gln 50. These first structures of human hookworm parasite GSTs could aid the design of novel hookworm drugs. CONCLUSION The 3-dimensional structures of Na-GST-1 and Na-GST-2 show two views of human hookworm GSTs. While the GST-complex structure of Na-GST-2 reveals a typical GST G-site that of Na-GST-1 suggests that there is some conformational flexibility required in order to bind the substrate GST. In addition, the overall binding cavities for both are larger, more open, as well as more accessible to diverse ligands than those of GSTs from organisms that have other major detoxifying mechanisms. The results from this study could aid in the design of novel drugs and vaccine antigens.
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Affiliation(s)
- Oluwatoyin A Asojo
- Department of Pathology and Microbiology, College of Medicine Nebraska Medical Center, Omaha NE 68198-6495, USA
| | - Kohei Homma
- Department of Pathology and Microbiology, College of Medicine Nebraska Medical Center, Omaha NE 68198-6495, USA
| | - Meghan Sedlacek
- Department of Pathology and Microbiology, College of Medicine Nebraska Medical Center, Omaha NE 68198-6495, USA
| | - Michelle Ngamelue
- Department of Pathology and Microbiology, College of Medicine Nebraska Medical Center, Omaha NE 68198-6495, USA
| | - Gaddam N Goud
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University Medical Center, Washington DC, 20037, USA
| | - Bin Zhan
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University Medical Center, Washington DC, 20037, USA
| | - Vehid Deumic
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University Medical Center, Washington DC, 20037, USA
| | - Oluyomi Asojo
- Department of Pathology and Microbiology, College of Medicine Nebraska Medical Center, Omaha NE 68198-6495, USA
| | - Peter J Hotez
- Department of Microbiology, Immunology, and Tropical Medicine, The George Washington University Medical Center, Washington DC, 20037, USA
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Gene discovery for the carcinogenic human liver fluke, Opisthorchis viverrini. BMC Genomics 2007; 8:189. [PMID: 17587442 PMCID: PMC1913519 DOI: 10.1186/1471-2164-8-189] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2007] [Accepted: 06/22/2007] [Indexed: 12/30/2022] Open
Abstract
Background Cholangiocarcinoma (CCA) – cancer of the bile ducts – is associated with chronic infection with the liver fluke, Opisthorchis viverrini. Despite being the only eukaryote that is designated as a 'class I carcinogen' by the International Agency for Research on Cancer, little is known about its genome. Results Approximately 5,000 randomly selected cDNAs from the adult stage of O. viverrini were characterized and accounted for 1,932 contigs, representing ~14% of the entire transcriptome, and, presently, the largest sequence dataset for any species of liver fluke. Twenty percent of contigs were assigned GO classifications. Abundantly represented protein families included those involved in physiological functions that are essential to parasitism, such as anaerobic respiration, reproduction, detoxification, surface maintenance and feeding. GO assignments were well conserved in relation to other parasitic flukes, however, some categories were over-represented in O. viverrini, such as structural and motor proteins. An assessment of evolutionary relationships showed that O. viverrini was more similar to other parasitic (Clonorchis sinensis and Schistosoma japonicum) than to free-living (Schmidtea mediterranea) flatworms, and 105 sequences had close homologues in both parasitic species but not in S. mediterranea. A total of 164 O. viverrini contigs contained ORFs with signal sequences, many of which were platyhelminth-specific. Examples of convergent evolution between host and parasite secreted/membrane proteins were identified as were homologues of vaccine antigens from other helminths. Finally, ORFs representing secreted proteins with known roles in tumorigenesis were identified, and these might play roles in the pathogenesis of O. viverrini-induced CCA. Conclusion This gene discovery effort for O. viverrini should expedite molecular studies of cholangiocarcinogenesis and accelerate research focused on developing new interventions, drugs and vaccines, to control O. viverrini and related flukes.
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Xiao S, Zhan B, Xue J, Goud GN, Loukas A, Liu Y, Williamson A, Liu S, Deumic V, Hotez P. The evaluation of recombinant hookworm antigens as vaccines in hamsters (Mesocricetus auratus) challenged with human hookworm, Necator americanus. Exp Parasitol 2007; 118:32-40. [PMID: 17645877 DOI: 10.1016/j.exppara.2007.05.010] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2007] [Revised: 05/25/2007] [Accepted: 05/29/2007] [Indexed: 11/23/2022]
Abstract
We have previously reported the successful adaptation of human hookworm Necator americanus in the golden hamster, Mesocricetus auratus. This animal model was used to test a battery of hookworm (N. americanus and Ancylostoma caninum) recombinant antigens as potential vaccine antigens. Hamsters immunized a leading vaccine candidate N. americanus-Ancylostoma secreted protein 2 (Na-ASP-2) and challenged with N. americanus infective larvae (L3), resulted in 30-46.2% worm reduction over the course of three vaccine trials, relative to adjuvant controls. In addition, significant reduction of worm burdens was also observed in the hamsters immunized with adult hookworm antigens A. caninum aspartic protease 1 (Ac-APR-1); A. caninum-glutathione-S transferase 1 (Ac-GST-1) and Necator cysteine proteases 2 (Na-CP-2) (44.4%, 50.6%, and 29.3%, respectively). Our data on the worm burden reductions afforded by these hookworm antigens approximate the level of protection reported previously from dogs challenged with A. caninum L3, and provide additional evidence to support these hookworm antigens as vaccine candidates for human hookworm infection. The hamster model of N. americanus provides useful information for the selection of antigens to be tested in downstream vaccine development.
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Affiliation(s)
- Shuhua Xiao
- Institute of Parasitic Diseases, Chinese Center for Disease Control and Prevention, Shanghai 200025, China
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82
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Bethony JM, Loukas A, Hotez PJ, Knox DP. Vaccines against blood-feeding nematodes of humans and livestock. Parasitology 2007; 133 Suppl:S63-79. [PMID: 17274849 DOI: 10.1017/s0031182006001818] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
This paper summarises the progress towards vaccine development against the major blood-feeding nematodes of man and livestock, the hookworms and Haemonchus contortus, respectively. The impact of the diseases and the drivers for vaccine development are summarized as well as the anticipated impact of the host immune response on vaccine design. The performance requirements are discussed and progress towards these objectives using defined larval and adult antigens, many of these being shared between species. Specific examples include the Ancylostoma secreted proteins and homologues in Haemonchus as well as proteases used for digestion of the blood meal. This discussion shows that many of the major vaccine candidates are shared between these blood-feeding species, not only those from the blood-feeding stages but also those expressed by infective L3s in the early stages of infection. Challenges for the future include: exploiting the expanding genome information for antigen discovery, use of different recombinant protein expression systems, formulation with new adjuvants, and novel methods of field testing vaccine efficacy.
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Affiliation(s)
- J M Bethony
- Centro de Pesquisas René Rachou/CPqRR, A FIOCRUZ em Minas Gerais. Rene Rachou Research Center/CPqRR, The Oswaldo Cruz Foundation, Minas Gerais, Brazil.
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83
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Fujiwara RT, Zhan B, Mendez S, Loukas A, Bueno LL, Wang Y, Plieskatt J, Oksov Y, Lustigman S, Bottazzi ME, Hotez P, Bethony JM. Reduction of worm fecundity and canine host blood loss mediates protection against hookworm infection elicited by vaccination with recombinant Ac-16. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2007; 14:281-7. [PMID: 17267592 PMCID: PMC1828853 DOI: 10.1128/cvi.00404-06] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Hookworm infection is one of most important parasitic infection of humans, occurring in 740 million people. Here we report the protective vaccination of dogs with Ac-16, an immunodominant surface antigen from the hookworm Ancylostoma caninum. We show that immunization with Ac-16 formulated with AS03 elicited specific humoral and cellular immune responses and provided partial protection against hookworm infection and morbidity as evidenced by a significant reduction of hookworm egg counts (64% reduction; P = 0.0078) and worm-induced blood loss (P < 0.05). Moreover, specific anti-Ac-16 antibodies recognized the native protein on the surface of third-stage larvae and blocked their migration through tissue in vitro. Our data support the use of Ac-16 as a potential candidate for vaccination against hookworm infection.
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Affiliation(s)
- Ricardo T Fujiwara
- Department of Microbiology, Immunology and Tropical Medicine, The George Washington University, Ross Hall Room 727, 2300 Eye St. NW, Washington, DC 20037, USA
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84
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Dubreuil G, Magliano M, Deleury E, Abad P, Rosso MN. Transcriptome analysis of root-knot nematode functions induced in the early stages of parasitism. THE NEW PHYTOLOGIST 2007; 176:426-436. [PMID: 17692078 DOI: 10.1111/j.1469-8137.2007.02181.x] [Citation(s) in RCA: 105] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Root-knot nematodes of the genus Meloidogyne are obligate biotrophic parasites able to infest > 2000 plant species. The nematode effectors responsible for disease development are involved in the adaptation of the parasite to its host environment and host response modulation. Here, the differences between the transcriptomes of preparasitic exophytic second-stage juveniles (J2) and parasitic endophytic third-stage juveniles (J3) of Meloidogyne incognita were investigated. Genes up-regulated at the endophytic stage were isolated by suppression subtractive hybridization and validated by dot blots and real-time quantitative polymerase chain reaction (PCR). Up-regulation was demonstrated for genes involved in detoxification and protein degradation, for a gene encoding a putative secreted protein and for genes of unknown function. Transcripts of the glutathione S-transferase gene Mi-gsts-1 were 27 times more abundant in J3 than in J2. The observed Mi-gsts-1 expression in the oesophageal secretory glands and the results of functional analyses based on RNA interference suggest that glutathione S-transferases are secreted during parasitism and are required for completion of the nematode life cycle in its host. Secreted glutathione S-transferases may protect the parasite against reactive oxygen species or modulate the plant responses triggered by pathogen attack.
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Affiliation(s)
- G Dubreuil
- INRA-UNSA-CNRS, UMR 1064, Plant-Microbe Interactions and Plant Health, 400, Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France
| | - M Magliano
- INRA-UNSA-CNRS, UMR 1064, Plant-Microbe Interactions and Plant Health, 400, Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France
| | - E Deleury
- INRA-UNSA-CNRS, UMR 1064, Plant-Microbe Interactions and Plant Health, 400, Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France
| | - P Abad
- INRA-UNSA-CNRS, UMR 1064, Plant-Microbe Interactions and Plant Health, 400, Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France
| | - M N Rosso
- INRA-UNSA-CNRS, UMR 1064, Plant-Microbe Interactions and Plant Health, 400, Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France
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