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Yarlett N, Jarroll EL, Morada M, Lloyd D. Protists: Eukaryotic single-celled organisms and the functioning of their organelles. Adv Microb Physiol 2024; 84:243-307. [PMID: 38821633 DOI: 10.1016/bs.ampbs.2024.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/02/2024]
Abstract
Organelles are membrane bound structures that compartmentalize biochemical and molecular functions. With improved molecular, biochemical and microscopy tools the diversity and function of protistan organelles has increased in recent years, providing a complex panoply of structure/function relationships. This is particularly noticeable with the description of hydrogenosomes, and the diverse array of structures that followed, having hybrid hydrogenosome/mitochondria attributes. These diverse organelles have lost the major, at one time, definitive components of the mitochondrion (tricarboxylic cycle enzymes and cytochromes), however they all contain the machinery for the assembly of Fe-S clusters, which is the single unifying feature they share. The plasticity of organelles, like the mitochondrion, is therefore evident from its ability to lose its identity as an aerobic energy generating powerhouse while retaining key ancestral functions common to both aerobes and anaerobes. It is interesting to note that the apicoplast, a non-photosynthetic plastid that is present in all apicomplexan protozoa, apart from Cryptosporidium and possibly the gregarines, is also the site of Fe-S cluster assembly proteins. It turns out that in Cryptosporidium proteins involved in Fe-S cluster biosynthesis are localized in the mitochondrial remnant organelle termed the mitosome. Hence, different organisms have solved the same problem of packaging a life-requiring set of reactions in different ways, using different ancestral organelles, discarding what is not needed and keeping what is essential. Don't judge an organelle by its cover, more by the things it does, and always be prepared for surprises.
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Affiliation(s)
- Nigel Yarlett
- Haskins Laboratories, Pace University, New York, NY, United States; The Department of Chemistry and Physical Sciences, Pace University, New York, NY, United States.
| | - Edward L Jarroll
- Department of Biological Sciences, CUNY-Lehman College, Bronx, NY, United States
| | - Mary Morada
- Haskins Laboratories, Pace University, New York, NY, United States
| | - David Lloyd
- Schools of Biosciences and Engineering, Cardiff University, Wales, United Kingdom
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2
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Shih HW, Alas GCM, Paredez AR. Encystation stimuli sensing is mediated by adenylate cyclase AC2-dependent cAMP signaling in Giardia. Nat Commun 2023; 14:7245. [PMID: 37945557 PMCID: PMC10636121 DOI: 10.1038/s41467-023-43028-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 10/26/2023] [Indexed: 11/12/2023] Open
Abstract
Protozoan parasites use cAMP signaling to precisely regulate the place and time of developmental differentiation, yet it is unclear how this signaling is initiated. Encystation of the intestinal parasite Giardia lamblia can be activated by multiple stimuli, which we hypothesize result in a common physiological change. We demonstrate that bile alters plasma membrane fluidity by reducing cholesterol-rich lipid microdomains, while alkaline pH enhances bile function. Through depletion of the cAMP producing enzyme Adenylate Cyclase 2 (AC2) and the use of a newly developed Giardia-specific cAMP sensor, we show that AC2 is necessary for encystation stimuli-induced cAMP upregulation and activation of downstream signaling. Conversely, over expression of AC2 or exogenous cAMP were sufficient to initiate encystation. Our findings indicate that encystation stimuli induce membrane reorganization, trigger AC2-dependent cAMP upregulation, and initiate encystation-specific gene expression, thereby advancing our understanding of a critical stage in the life cycle of a globally important parasite.
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Affiliation(s)
- Han-Wei Shih
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
| | - Germain C M Alas
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
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3
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Shih HW, Alas GCM, Paredez AR. Encystation stimuli sensing mediated by adenylate cyclase AC2-dependent cAMP signaling in Giardia. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.10.536239. [PMID: 37090513 PMCID: PMC10120678 DOI: 10.1101/2023.04.10.536239] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
Protozoan parasites use cAMP signaling to precisely regulate the place and time of developmental differentiation, yet it is unclear how this signaling is initiated. Encystation of the intestinal parasite Giardia lamblia can be activated by multiple stimuli, which we hypothesize result in a common physiological change. We demonstrate that bile alters plasma membrane fluidity by reducing cholesterol-rich lipid microdomains, while alkaline pH enhances bile function. Through depletion of the cAMP producing enzyme Adenylate Cyclase 2 (AC2) and the use of a newly developed Giardia-specific cAMP sensor, we show that AC2 is necessary for encystation stimuli-induced cAMP upregulation and activation of downstream signaling. Conversely, over expression of AC2 or exogenous cAMP were sufficient to initiate encystation. Our findings indicate that encystation stimuli induce membrane reorganization, trigger AC2-dependent cAMP upregulation, and initiate encystation-specific gene expression, thereby advancing our understanding of a critical stage in the life cycle of a globally important parasite.
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Affiliation(s)
- Han-Wei Shih
- Department of Biology, University of Washington, Seattle, Washington 98195
| | - Germain C M Alas
- Department of Biology, University of Washington, Seattle, Washington 98195
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4
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Einarsson E, Svärd SG. Encystation of Giardia intestinalis—a Journey from the Duodenum to the Colon. CURRENT TROPICAL MEDICINE REPORTS 2015. [DOI: 10.1007/s40475-015-0048-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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5
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Comparative biochemistry of Giardia, Hexamita and Spironucleus: Enigmatic diplomonads. Mol Biochem Parasitol 2014; 197:43-9. [DOI: 10.1016/j.molbiopara.2014.10.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 10/03/2014] [Accepted: 10/03/2014] [Indexed: 12/30/2022]
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6
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Strategies to discover the structural components of cyst and oocyst walls. EUKARYOTIC CELL 2013; 12:1578-87. [PMID: 24096907 DOI: 10.1128/ec.00213-13] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Cysts of Giardia lamblia and Entamoeba histolytica and oocysts of Toxoplasma gondii and Cryptosporidium parvum are the infectious and sometimes diagnostic forms of these parasites. To discover the structural components of cyst and oocyst walls, we have developed strategies based upon a few simple assumptions. Briefly, the most abundant wall proteins are identified by monoclonal antibodies or mass spectrometry. Structural components include a sugar polysaccharide (chitin for Entamoeba, β-1,3-linked glucose for Toxoplasma, and β-1,3-linked GalNAc for Giardia) and/or acid-fast lipids (Toxoplasma and Cryptosporidium). Because Entamoeba cysts and Toxoplasma oocysts are difficult to obtain, studies of walls of nonhuman pathogens (E. invadens and Eimeria, respectively) accelerate discovery. Biochemical methods to dissect fungal walls work well for cyst and oocyst walls, although the results are often unexpected. For example, echinocandins, which inhibit glucan synthases and kill fungi, arrest the development of oocyst walls and block their release into the intestinal lumen. Candida walls are coated with mannans, while Entamoeba cysts are coated in a dextran-like glucose polymer. Models for cyst and oocyst walls derive from their structural components and organization within the wall. Cyst walls are composed of chitin fibrils and lectins that bind chitin (Entamoeba) or fibrils of the β-1,3-GalNAc polymer and lectins that bind the polymer (Giardia). Oocyst walls of Toxoplasma have two distinct layers that resemble those of fungi (β-1,3-glucan in the inner layer) or mycobacteria (acid-fast lipids in the outer layer). Oocyst walls of Cryptosporidium have a rigid bilayer of acid-fast lipids and inner layer of oocyst wall proteins.
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7
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A new set of carbohydrate-positive vesicles in encysting Giardia lamblia. Protist 2012; 164:261-71. [PMID: 23266141 DOI: 10.1016/j.protis.2012.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2012] [Revised: 11/04/2012] [Accepted: 11/05/2012] [Indexed: 11/24/2022]
Abstract
Giardia lamblia is a protozoan parasite that presents both trophozoite and cyst forms. In this study, the distribution of the different sugar residues and the origin of the carbohydrate components of the cyst wall were studied using transmission electron microscopy, ultrastructural cytochemistry for carbohydrate detection and immunocytochemistry. Immunofluorescence microscopy using anti-cyst wall protein 1 (CWP1) and gold- and fluorescent-conjugated lectins, such as WGA and DBA, were also used. Interestingly, a population of carbohydrate-containing vesicles, distinct from the encystation-specific vesicles (ESVs) was found in the encysting cells and was named encystation carbohydrate-positive vesicles (ECVs). The differences between the ECVs and the ESVs were: (1) they are electron-translucent, whereas ESVs are electron dense; (2) they do not react with antibodies against cyst wall proteins; (3) the contents are positive for carbohydrates, whereas ESVs display a negative reaction; and (4) they exhibit a positive labeling for DBA indicating the presence of N-acetyl-galactosamine, whereas ESVs are negative. To evaluate if ECVs could be vesicles involved in the endocytic pathway, endocytic markers were used. No co-localization of these markers with ECVs was observed. We suggest that the ECVs may represent a new structure involved in cyst wall formation.
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Jiráková K, Kulda J, Nohýnková E. How nuclei of Giardia pass through cell differentiation: semi-open mitosis followed by nuclear interconnection. Protist 2011; 163:465-79. [PMID: 22209008 DOI: 10.1016/j.protis.2011.11.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Accepted: 11/10/2011] [Indexed: 12/30/2022]
Abstract
Differentiation into infectious cysts (encystation) and multiplication of pathogenic trophozoites after hatching from the cyst (excystation) are fundamental processes in the life cycle of the human intestinal parasite Giardia intestinalis. During encystation, a bi-nucleated trophozoite transforms to a dormant tetra-nucleated cyst enveloped by a protective cyst wall. Nuclear division during encystation is not followed by cytokinesis. In contrast to the well-studied mechanism of cyst wall formation, information on nuclei behavior is incomplete and basic cytological data are lacking. Here we present evidence that (1) the nuclei divide by semi-open mitosis during early encystment; (2) the daughter nuclei coming from different parent nuclei are always arranged in pairs; (3) in both pairs, the nuclei are interconnected via bridges formed by fusion of their nuclear envelopes; (4) each interconnected nuclear pair is associated with one basal body tetrad of the undivided diplomonad mastigont; and (5) the interconnection between nuclei persists through the cyst stage being a characteristic feature of encysted Giardia. Based on the presented results, a model of nuclei behavior during Giardia differentiation is proposed.
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Affiliation(s)
- Klára Jiráková
- Department of Tropical Medicine, 1(st) Faculty of Medicine, Charles University in Prague and Faculty Hospital Bulovka, Studnickova 7, Prague 2, 128 00, Czech Republic
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9
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Blank CE. An expansion of age constraints for microbial clades that lack a conventional fossil record using phylogenomic dating. J Mol Evol 2011; 73:188-208. [PMID: 22105429 DOI: 10.1007/s00239-011-9467-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2011] [Accepted: 10/24/2011] [Indexed: 01/22/2023]
Abstract
Most microbial taxa lack a conventional microfossil or biomarker record, and so we currently have little information regarding how old most microbial clades and their associated traits are. Building on the previously published oxygen age constraint, two new age constraints are proposed based on the ability of microbial clades to metabolize chitin and aromatic compounds derived from lignin. Using the archaeal domain of life as a test case, phylogenetic analyses, along with published metabolic and genetic data, showed that members of the Halobacteriales and Thermococcales are able to metabolize chitin. Ancestral state reconstruction combined with phylogenetic analysis of the genes underlying chitin degradation predicted that the ancestors of these two groups were also likely able to metabolize chitin or chitin-related compounds. These two clades were therefore assigned a maximum age of 1.0 Ga (when chitin likely first appeared). Similar analyses also predicted that the ancestor to the Sulfolobus solfataricus-Sulfolobus islandicus clade was able to metabolize phenol using catechol dioxygenase, so this clade was assigned a maximum age of 475 Ma. Inferred ages of archaeal clades using relaxed molecular clocks with the new age constraints were consistent with those inferred with the oxygen age constraints. This work expands our current toolkit to include Paleoproterozoic, Neoproterozoic, and Paleozoic age constraints, and should aid in our ability to phylogenetically reconstruct the antiquity of a wide array of microbial clades and their associated morphological and biogeochemical traits, spanning deep geologic time. Such hypotheses-although built upon evolutionary inferences-are fundamentally testable.
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Affiliation(s)
- Carrine E Blank
- Department of Geosciences, University of Montana, 32 Campus Drive #1296, Missoula, MT 59812-1296, USA.
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10
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Cyst and encystment in protozoan parasites: optimal targets for new life-cycle interrupting strategies? Trends Parasitol 2011; 27:450-8. [PMID: 21775209 DOI: 10.1016/j.pt.2011.06.003] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 06/15/2011] [Accepted: 06/16/2011] [Indexed: 11/24/2022]
Abstract
Certain protozoan parasites use survival strategies to reside outside the host such as the formation of cysts. This dormant and resistant stage results from the complex process of encystment that involves diverse molecular and cellular modifications. The stimuli and changes associated with cyst biogenesis are a matter of ongoing studies in human and animal protozoan parasites such as amoeba and Giardia species because blocking every step in the encystment pathway should, in theory, interrupt their life cycles. The present review thoroughly examines this essential process in those protozoan parasites and discusses the possibility of using that information to develop new kinds of anti-parasite specific and life cycle-interrupting drugs, aimed at holding back the dissemination of these infections.
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Samuelson J, Robbins P. A simple fibril and lectin model for cyst walls of Entamoeba and perhaps Giardia. Trends Parasitol 2011; 27:17-22. [PMID: 20934911 DOI: 10.1016/j.pt.2010.09.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/03/2010] [Accepted: 09/07/2010] [Indexed: 01/24/2023]
Abstract
Cyst walls of Entamoeba and Giardia protect them from environmental insults, stomach acids, and intestinal proteases. Each cyst wall contains a sugar homopolymer: chitin in Entamoeba and a unique N-acetylgalactosamine (GalNAc) homopolymer in Giardia. Entamoeba cyst wall proteins include Jacob lectins (carbohydrate-binding proteins) that crosslink chitin, chitinases that degrade chitin, and Jessie lectins that make walls impermeable. Giardia cyst wall proteins are also lectins that bind fibrils of the GalNAc homopolymer. Although many of the details remain to be determined for the cyst wall of Giardia, current data suggest a relatively simple fibril and lectin model for the Entamoeba cyst wall.
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Affiliation(s)
- John Samuelson
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, MA, USA.
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12
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Davids BJ, Gilbert MA, Liu Q, Reiner DS, Smith AJ, Lauwaet T, Lee C, McArthur AG, Gillin FD. An atypical proprotein convertase in Giardia lamblia differentiation. Mol Biochem Parasitol 2010; 175:169-80. [PMID: 21075147 DOI: 10.1016/j.molbiopara.2010.11.008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Revised: 10/29/2010] [Accepted: 11/05/2010] [Indexed: 01/24/2023]
Abstract
Proteolytic activity is important in the lifecycles of parasites and their interactions with hosts. Cysteine proteases have been best studied in Giardia, but other protease classes have been implicated in growth and/or differentiation. In this study, we employed bioinformatics to reveal the complete set of putative proteases in the Giardia genome. We identified 73 peptidase homologs distributed over 5 catalytic classes in the genome. Serial analysis of gene expression of the G. lamblia lifecycle found thirteen protease genes with significant transcriptional variation over the lifecycle, with only one serine protease transcript upregulated late in encystation. The translated gene sequence of this encystation-specific transcript was most similar to eukaryotic subtilisin-like proprotein convertases (SPC), although the typical catalytic triad was not identified. Epitope-tagged gSPC protein expressed in Giardia under its own promoter was upregulated during encystation with highest expression in cysts and it localized to encystation-specific secretory vesicles (ESV). Total gSPC from encysting cells produced proteolysis in gelatin gels that co-migrated with the epitope-tagged protease in immunoblots. Immuno-purified gSPC also had gelatinase activity. To test whether endogenous gSPC activity is involved in differentiation, trophozoites and cysts were exposed to the specific serine proteinase inhibitor 4-(2-aminoethyl)-benzenesulfonyl fluoride hydrochloride (AEBSF). After 21 h encystation, a significant decrease in ESV was observed with 1mM AEBSF and by 42 h the number of cysts was significantly reduced, but trophozoite growth was not inhibited. Concurrently, levels of cyst wall proteins 1 and 2, and AU1-tagged gSPC protein itself were decreased. Excystation of G. muris cysts was also significantly reduced in the presence of AEBSF. These results support the idea that serine protease activity is essential for Giardia encystation and excystation.
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Affiliation(s)
- B J Davids
- Department of Pathology, University of California, San Diego, CA 92103-8416, USA.
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Staake M, Chauhan J, Zhou D, Shanker A, De Chatterjee A, Das S, Patterson SE. Phosphonoxins III: synthesis of α-aminophosphonate analogs of antifungal polyoxins with anti-Giardia activity. Org Lett 2010; 12:4596-9. [PMID: 20857975 PMCID: PMC2962623 DOI: 10.1021/ol101913t] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
A synthesis of α-aminophosphonate analogs of polyoxins, termed phosphonoxin C1, C2, and C3, has been achieved. The key step was the addition of lithium dimethyl phosphite to the aldehyde of a protected threose derivative. α-Hydroxyphosphonate analogs C4 and C5 were also obtained by taking advantage of an unprecedented conversion of an azide to hydroxyl during treatment with hydrogen on palladium on carbon. The resulting phosphonoxin C5 inhibited the growth of an intestinal protozoan, Giardia lamblia, at low micromolar concentration.
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Affiliation(s)
- Michael Staake
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Jay Chauhan
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Ding Zhou
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Aaron Shanker
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519
| | - Atasi De Chatterjee
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519
| | - Siddhartha Das
- Department of Biological Sciences, University of Texas at El Paso, El Paso, TX 79968-0519
| | - Steven E. Patterson
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
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Chatterjee A, Carpentieri A, Ratner DM, Bullitt E, Costello CE, Robbins PW, Samuelson J. Giardia cyst wall protein 1 is a lectin that binds to curled fibrils of the GalNAc homopolymer. PLoS Pathog 2010; 6:e1001059. [PMID: 20808847 PMCID: PMC2924369 DOI: 10.1371/journal.ppat.1001059] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2010] [Accepted: 07/22/2010] [Indexed: 11/18/2022] Open
Abstract
The infectious and diagnostic stage of Giardia lamblia (also known as G. intestinalis or G. duodenalis) is the cyst. The Giardia cyst wall contains fibrils of a unique beta-1,3-linked N-acetylgalactosamine (GalNAc) homopolymer and at least three cyst wall proteins (CWPs) composed of Leu-rich repeats (CWP(LRR)) and a C-terminal conserved Cys-rich region (CWP(CRR)). Our goals were to dissect the structure of the cyst wall and determine how it is disrupted during excystation. The intact Giardia cyst wall is thin (approximately 400 nm), easily fractured by sonication, and impermeable to small molecules. Curled fibrils of the GalNAc homopolymer are restricted to a narrow plane and are coated with linear arrays of oval-shaped protein complex. In contrast, cyst walls of Giardia treated with hot alkali to deproteinate fibrils of the GalNAc homopolymer are thick (approximately 1.2 microm), resistant to sonication, and permeable. The deproteinated GalNAc homopolymer, which forms a loose lattice of curled fibrils, is bound by native CWP1 and CWP2, as well as by maltose-binding protein (MBP)-fusions containing the full-length CWP1 or CWP1(LRR). In contrast, neither MBP alone nor MBP fused to CWP1(CRR) bind to the GalNAc homopolymer. Recombinant CWP1 binds to the GalNAc homopolymer within secretory vesicles of Giardia encysting in vitro. Fibrils of the GalNAc homopolymer are exposed during excystation or by treatment of heat-killed cysts with chymotrypsin, while deproteinated fibrils of the GalNAc homopolymer are degraded by extracts of Giardia cysts but not trophozoites. These results show the Leu-rich repeat domain of CWP1 is a lectin that binds to curled fibrils of the GalNAc homopolymer. During excystation, host and Giardia proteases appear to degrade bound CWPs, exposing fibrils of the GalNAc homopolymer that are digested by a stage-specific glycohydrolase.
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Affiliation(s)
- Aparajita Chatterjee
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Andrea Carpentieri
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Daniel M. Ratner
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America
| | - Esther Bullitt
- Department of Biophysics and Physiology, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Catherine E. Costello
- Department of Biochemistry, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Phillips W. Robbins
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America
| | - John Samuelson
- Department of Molecular and Cell Biology, Boston University Goldman School of Dental Medicine, Boston, Massachusetts, United States of America
- * E-mail:
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Abstract
The eukaryotic intestinal parasite Giardia intestinalis was first described in 1681, when Antonie van Leeuwenhoek undertook a microscopic examination of his own diarrhoeal stool. Nowadays, although G. intestinalis is recognized as a major worldwide contributor to diarrhoeal disease in humans and other mammals, the disease mechanisms are still poorly understood. Owing to its reduced complexity and proposed early evolutionary divergence, G. intestinalis is used as a model eukaryotic system for studying many basic cellular processes. In this Review we discuss recent discoveries in the molecular cell biology and pathogenesis of G. intestinalis.
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16
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Aguilar-Díaz H, Díaz-Gallardo M, Laclette JP, Carrero JC. In vitro induction of Entamoeba histolytica cyst-like structures from trophozoites. PLoS Negl Trop Dis 2010; 4:e607. [PMID: 20169067 PMCID: PMC2821915 DOI: 10.1371/journal.pntd.0000607] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2009] [Accepted: 12/29/2009] [Indexed: 11/18/2022] Open
Abstract
Inhibition of encystment can be conceived as a potentially useful mechanism to block the transmission of Entamoeba histolytica under natural conditions. Unfortunately, amoeba encystment has not been achieved in vitro and drugs inhibiting the formation of cysts are not available. Luminal conditions inducing encystment in vivo are also unknown, but cellular stress such as exposure to reactive oxygen species from immune cells or intestinal microbiota could be involved. A role for certain divalent cations as cofactors of enzymes involved in excystment has also been described. In this study, we show that trophozoite cultures, treated with hydrogen peroxide in the presence of trace amounts of several cations, transform into small-sized spherical and refringent structures that exhibit resistance to different detergents. Ultrastructural analysis under scanning and transmission electron microscopy revealed multinucleated structures (some with four nuclei) with smooth, thick membranes and multiple vacuoles. Staining with calcofluor white, as well as an ELISA binding assay using wheat germ agglutinin, demonstrated the presence of polymers of N-acetylglucosamine (chitin), which is the primary component of the natural cyst walls. Over-expression of glucosamine 6-phosphate isomerase, likely to be the rate-limiting enzyme in the chitin synthesis pathway, was also confirmed by RT-PCR. These results suggest that E. histolytica trophozoites activated encystment pathways when exposed to our treatment.
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Affiliation(s)
- Hugo Aguilar-Díaz
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
| | - Martha Díaz-Gallardo
- Department of Developmental Genetics and Molecular Physiology, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Morelos, México
| | - Juan P. Laclette
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
- * E-mail: (JPL); (JCC)
| | - Julio C. Carrero
- Department of Immunology, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, Ciudad de México, México
- * E-mail: (JPL); (JCC)
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Xiao Y, Yin J, Jiang N, Xiang M, Hao L, Lu H, Sang H, Liu X, Xu H, Ankarklev J, Lindh J, Chen Q. Seroepidemiology of human Toxoplasma gondii infection in China. BMC Infect Dis 2010; 10:4. [PMID: 20055991 PMCID: PMC2818656 DOI: 10.1186/1471-2334-10-4] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2009] [Accepted: 01/07/2010] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Toxoplasmosis is an important zoonotic parasitic disease worldwide. In immune competent individuals, Toxoplasma gondii preferentially infects tissues of central nervous systems, which might be an adding factor of certain psychiatric disorders. Congenital transmission of T. gondii during pregnancy has been regarded as a risk factor for the health of newborn infants. While in immune-compromised individuals, the parasite can cause life-threatening infections. This study aims to investigate the prevalence of T. gondii infection among clinically healthy individuals and patients with psychiatric disorders in China and to identify the potential risk factors related to the vulnerability of infection in the population. METHODS Serum samples from 2634 healthy individuals and 547 patients with certain psychiatric disorders in Changchun and Daqing in the northeast, and in Shanghai in the south of China were examined respectively for the levels of anti-T. gondii IgG by indirect ELISA and a direct agglutination assay. Prevalence of T. gondii infection in the Chinese population in respect of gender, age, residence and health status was systematically analyzed. RESULTS The overall anti-T. gondii IgG prevalence in the study population was 12.3%. In the clinically healthy population 12.5% was sero-positive and in the group with psychiatric disorders 11.3% of these patients were positive with anti-T. gondii IgG. A significant difference (P = 0.004) was found between male and female in the healthy population, the seroprevalence was 10.5% in men versus 14.3% in women. Furthermore, the difference of T. gondii infection rate between male and female in the 20-19 year's group was more obvious, with 6.4% in male population and 14.6% in female population. CONCLUSION A significant higher prevalence of T. gondii infection was observed in female in the clinically healthy population. No correlation was found between T. gondii infection and psychiatric disorders in this study. Results suggest that women are more exposed to T. gondii infection than men in China. The data argue for deeper investigations for the potential risk factors that threat the female populations.
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Affiliation(s)
- Yue Xiao
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, PR China
| | - Jigang Yin
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, PR China
| | - Ning Jiang
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, PR China
| | - Mei Xiang
- The Second Hospital of Jilin University, Ziqiang Street 218, Changchun 10041, PR China
| | - Lili Hao
- Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Beijing, Dong Dan San Tiao, Beijing 100730, PR China
| | - Huijun Lu
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, PR China
| | - Hong Sang
- The Sixth Hospital of Changchun City, North Round Road 4596, Changchun 130040, PR China
| | - Xianying Liu
- The Second Hospital of Jilin University, Ziqiang Street 218, Changchun 10041, PR China
| | - Huiji Xu
- Changzheng Hospital, Shanghai, Fengyang Road 415, Shanghai 200003, PR China
| | - Johan Ankarklev
- Department of Parasitology, Mycology and Environmental Microbiology, Swedish Institute for Infectious Disease Control, Nobels väg 18, 171 82 Solna, Sweden
| | - Johan Lindh
- Department of Parasitology, Mycology and Environmental Microbiology, Swedish Institute for Infectious Disease Control, Nobels väg 18, 171 82 Solna, Sweden
| | - Qijun Chen
- Key Laboratory of Zoonosis, Ministry of Education, Jilin University, Xi An Da Lu 5333, Changchun 130062, PR China
- Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Beijing, Dong Dan San Tiao, Beijing 100730, PR China
- Department of Parasitology, Mycology and Environmental Microbiology, Swedish Institute for Infectious Disease Control, Nobels väg 18, 171 82 Solna, Sweden
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Elias EV, Quiroga R, Gottig N, Nakanishi H, Nash TE, Neiman A, Lujan HD. Characterization of SNAREs determines the absence of a typical Golgi apparatus in the ancient eukaryote Giardia lamblia. J Biol Chem 2008; 283:35996-6010. [PMID: 18930915 DOI: 10.1074/jbc.m806545200] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Giardia is a eukaryotic protozoal parasite with unusual characteristics, such as the absence of a morphologically evident Golgi apparatus. Although both constitutive and regulated pathways for protein secretion are evident in Giardia, little is known about the mechanisms involved in vesicular docking and fusion. In higher eukaryotes, soluble N-ethylmaleimide-sensitive factor attachment protein receptors (SNAREs) of the vesicle-associated membrane protein and syntaxin families play essential roles in these processes. In this work we identified and characterized genes for 17 SNAREs in Giardia to define the minimal set of subcellular organelles present during growth and encystation, in particular the presence or not of a Golgi apparatus. Expression and localization of all Giardia SNAREs demonstrate their presence in distinct subcellular compartments, which may represent the extent of the endomembrane system in eukaryotes. Remarkably, Giardia SNAREs, homologous to Golgi SNAREs from other organisms, do not allow the detection of a typical Golgi apparatus in either proliferating or differentiating trophozoites. However, some features of the Golgi, such as the packaging and sorting function, seem to be performed by the endoplasmic reticulum and/or the nuclear envelope. Moreover, depletion of individual genes demonstrated that several SNAREs are essential for viability, whereas others are dispensable. Thus, Giardia requires a smaller number of SNAREs compared with other eukaryotes to accomplish all of the vesicle trafficking events that are critical for the growth and differentiation of this important human pathogen.
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Affiliation(s)
- Eliana V Elias
- Laboratory of Biochemistry and Molecular Biology, School of Medicine, Catholic University of Cordoba/National Council for Science and Technology, Cordoba CP X5004ASK, Argentina
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Zhou D, Staake M, Patterson SE. Phosphonoxins II: Diastereoselective Synthesis of Phosphonic Acid Analogues of Polyoxins. Org Lett 2008; 10:2179-82. [DOI: 10.1021/ol800552k] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ding Zhou
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Michael Staake
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
| | - Steven E. Patterson
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, Minnesota 55455
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20
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Lopez AB, Sener K, Trosien J, Jarroll EL, van Keulen H. UDP-N-acetylglucosamine 4'-epimerase from the intestinal protozoan Giardia intestinalis lacks UDP-glucose 4'-epimerase activity. J Eukaryot Microbiol 2007; 54:154-60. [PMID: 17403156 DOI: 10.1111/j.1550-7408.2007.00246.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The protozoan parasite Giardia intestinalis has a simple life cycle consisting of an intestinal trophozoite stage and an environmentally resistant cyst stage. The cyst is formed when a trophozoite encases itself within an external filamentous covering, the cyst wall, which is crucial to the cyst's survival outside of the host. The filaments in the cyst wall consist mainly of a beta (1-3) polymer of N-acetylgalactosamine. Its precursor, UDP-N-acetylgalactosamine, is synthesized from fructose 6-phosphate by a pathway of five inducible enzymes. The fifth, UDP-N-acetylglucosamine 4'-epimerase, epimerizes UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine reversibly. The epimerase of G. intestinalis lacks UDP-glucose/UDP-galactose 4'-epimerase activity and shows characteristic amino acyl residues to allow binding of only the larger UDP-N-acetylhexosamines. While the Giardia epimerase catalyzes the reversible epimerization of UDP-N-acetylglucosamine to UDP-N-acetylgalactosamine, the reverse reaction apparently is favored. The enzyme has a higher Vmax and a smaller Km in this direction. Therefore, an excess of UDP-N-acetylglucosamine is required to drive the reaction towards the synthesis of UDP-N-acetylgalactosamine, when it is needed for cyst wall formation. This forms the ultimate regulatory step in cyst wall biosynthesis.
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Affiliation(s)
- Alex B Lopez
- Department of Biological, Geological and Environmental Sciences, Cleveland State University, Cleveland, Ohio 44115, USA
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21
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Suk DH, Rejman D, Dykstra CC, Pohl R, Pankiewicz KW, Patterson SE. Phosphonoxins: rational design and discovery of a potent nucleotide anti-Giardia agent. Bioorg Med Chem Lett 2007; 17:2811-6. [PMID: 17360182 DOI: 10.1016/j.bmcl.2007.02.063] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2007] [Revised: 02/19/2007] [Accepted: 02/22/2007] [Indexed: 11/28/2022]
Abstract
Phosphonoxins, a new class of synthetic, rationally designed anti-microbial agents, are described. From this class a sub-micromolar inhibitor of Giardia trophozoite growth has been identified.
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Affiliation(s)
- Dae-Hwan Suk
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
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22
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Suk DH, Bonnac L, Dykstra CC, Pankiewicz KW, Patterson SE. Rational design and synthesis of novel nucleotide anti-Giardia agents. Bioorg Med Chem Lett 2007; 17:2064-7. [PMID: 17258459 DOI: 10.1016/j.bmcl.2007.01.014] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Revised: 01/03/2007] [Accepted: 01/05/2007] [Indexed: 11/27/2022]
Abstract
Design and synthesis of a novel nucleotide anti-Giardia agent that is micromolar inhibitor of Giardia trophozoite growth in culture is described.
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Affiliation(s)
- Dae-Hwan Suk
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
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23
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Davids BJ, Reiner DS, Birkeland SR, Preheim SP, Cipriano MJ, McArthur AG, Gillin FD. A new family of giardial cysteine-rich non-VSP protein genes and a novel cyst protein. PLoS One 2006; 1:e44. [PMID: 17183673 PMCID: PMC1762436 DOI: 10.1371/journal.pone.0000044] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2006] [Accepted: 10/10/2006] [Indexed: 11/18/2022] Open
Abstract
Since the Giardia lamblia cyst wall is necessary for survival in the environment and host infection, we tested the hypothesis that it contains proteins other than the three known cyst wall proteins. Serial analysis of gene expression during growth and encystation revealed a gene, "HCNCp" (High Cysteine Non-variant Cyst protein), that was upregulated late in encystation, and that resembled the classic Giardia variable surface proteins (VSPs) that cover the trophozoite plasmalemma. HCNCp is 13.9% cysteine, with many "CxxC" tetrapeptide motifs and a transmembrane sequence near the C-terminus. However, HCNCp has multiple "CxC" motifs rarely found in VSPs, and does not localize to the trophozoite plasmalemma. Moreover, the HCNCp C-terminus differed from the canonical VSP signature. Full-length epitope-tagged HCNCp expressed under its own promoter was upregulated during encystation with highest expression in cysts, including 42 and 21 kDa C-terminal fragments. Tagged HCNCp targeted to the nuclear envelope in trophozoites, and co-localized with cyst proteins to encystation-specific secretory vesicles during encystation. HCNCp defined a novel trafficking pathway as it localized to the wall and body of cysts, while the cyst proteins were exclusively in the wall. Unlike VSPs, HCNCp is expressed in at least five giardial strains and four WB subclones expressing different VSPs. Bioinformatics identified 60 additional large high cysteine membrane proteins (HCMp) containing > or = 20 CxxC/CxC's lacking the VSP-specific C-terminal CRGKA. HCMp were absent or rare in other model or parasite genomes, except for Tetrahymena thermophila with 30. MEME analysis classified the 61 gHCMp genes into nine groups with similar internal motifs. Our data suggest that HCNCp is a novel invariant cyst protein belonging to a new HCMp family that is abundant in the Giardia genome. HCNCp and the other HCMp provide a rich source for developing parasite-specific diagnostic reagents, vaccine candidates, and subjects for further research into Giardia biology.
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Affiliation(s)
- Barbara J Davids
- Department of Pathology, Division of Infectious Diseases, University of California, San Diego, California, United States of America.
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24
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Jiménez JC, Morelle W, Michalsky JC, Dei-Cas E. Excreted/secreted glycoproteins of G. intestinalis play an essential role in the antibody response. Parasitol Res 2006; 100:715-20. [PMID: 17171569 DOI: 10.1007/s00436-006-0339-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Accepted: 09/08/2006] [Indexed: 10/23/2022]
Abstract
In the present work, glycoproteins in the excretory/secretory products of G. intestinalis were identified and the reactivity in serum of immunized mice with these molecules was evaluated by western blotting before and after chemical treatment or enzymatic deglycosylation. Glycoproteins of 58 and 63 kDa were revealed in E/S products after periodic acid-Schiff (PAS) stain. Studies of carbohydrate specificity using digoxigenin-labeled lectins, revealed the presence of O-glycans and N-glycans. Chemical treatment of excretory/secretory products with sodium meta-periodate or enzymatic deglycosylation with N-glycosidase F reduced the reactivity in serum for proteins of 36, 58 and 63 kDa, respectively. These results show the presence of glycoproteins in E/S products of G. intestinalis and suggest that the antibody response is directed against glycoepitopes. The expression of carbohydrate moieties in the E/S-G. intestinalis may play an essential role in the antibody response and may be a target for serodiagnosis or immune intervention in human giardiasis.
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Affiliation(s)
- J C Jiménez
- Laboratory of Immunopathology, Institute of Biomedicine, Faculty of Medicine, Central University of Venezuela, Caracas, Venezuela.
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25
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Savioli L, Smith H, Thompson A. Giardia and Cryptosporidium join the 'Neglected Diseases Initiative'. Trends Parasitol 2006; 22:203-8. [PMID: 16545611 DOI: 10.1016/j.pt.2006.02.015] [Citation(s) in RCA: 518] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 02/10/2006] [Accepted: 02/28/2006] [Indexed: 11/17/2022]
Abstract
Giardia and Cryptosporidium are ubiquitous enteric protozoan pathogens that infect humans, domestic animals and wildlife worldwide. Both pathogens are significant causes of diarrhea and nutritional disorders in institutional and community settings. They are also significant waterborne pathogens. In developing regions of the world, Giardia and Cryptosporidium constitute part of the complex group of parasitic, bacterial and viral diseases that impair the ability to achieve full potential and impair development and socio-economic improvements. All diseases included in the WHO Neglected Diseases Initiative have a common link with poverty and, as the current view is to take a comprehensive approach to all these diseases, both Giardia and Cryptosporidium were included in 2004. Our current state of knowledge of Giardia and Cryptosporidium is summarized here, and some important questions are raised that need to be addressed if control strategies are to be effective.
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Affiliation(s)
- L Savioli
- Coordinator, Parasitic Diseases and Vector Control (PVC), Communicable Diseases Control, Prevention and Eradication (CPE), World Health Organization, 20 Avenue Appia, 1211 Geneva 27, Switzerland
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26
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Affiliation(s)
- Nigel Yarlett
- Department of Chemistry and Physical Sciences and Haskins Laboratories, Pace University, New York, NY 10038, USA
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