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Journal articles on the topic 'Giardia'

Author: Grafiati
Published: 4 June 2021
Last updated: 9 March 2023

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1

Šarić, Mirela, Anke Vahrmann, Daniela Niebur, Verena Kluempers, Adrian B. Hehl, and Henning Scholze. "Dual Acylation Accounts for the Localization of α19-Giardin in the Ventral Flagellum Pair of Giardia lamblia." Eukaryotic Cell 8, no. 10 (August 14, 2009): 1567–74. http://dx.doi.org/10.1128/ec.00136-09.

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ABSTRACT A Giardia-specific protein family denominated as α-giardins, represents the major protein component, besides tubulin, of the cytoskeleton of the human pathogenic parasite Giardia lamblia. One of its members, α19-giardin, carries an N-terminal sequence extension of MGCXXS, which in many proteins serves as a target for dual lipid conjugation: myristoylation at the glycine residue after removal of the methionine and palmitoylation at the cysteine residue. As the first experimental evidence of a lipid modification, we found α19-giardin to be associated with the membrane fraction of disrupted trophozoites. After heterologous coexpression of α19-giardin with giardial N-myristoyltransferase (NMT) in E scherichia coli, we found the protein in a myristoylated form. Additionally, after heterologous expression together with the palmitoyl transferase Pfa3 in Saccharomyces cerevisiae, α19-giardin associates with the membrane of the main vacuole. Immunocytochemical colocalization studies on wild-type Giardia trophozoites with tubulin provide evidence that α19-giardin exclusively localizes to the ventral pair of the giardial flagella. A mutant in which the putatively myristoylated N-terminal glycine residue was replaced by alanine lost this specific localization. Our findings suggest that the dual lipidation of α19-giardin is responsible for its specific flagellar localization.
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2

Shukla, Geeta, Tarveen Kaur, Rakesh Sehgal, Praveen Rishi, and Vijay Prabha. "Protective potential of L. acidophilus in murine giardiasis." Open Medicine 5, no. 4 (August 1, 2010): 456–63. http://dx.doi.org/10.2478/s11536-009-0139-x.

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AbstractThis study describes the in vivo activity of Lactobacillus acidophilus in Giardia lamblia infected BALB/c mice. Experimentally, it was observed that daily administration of lactobacilli 7 days before or in simultaneous inoculation with Giardia trophozoites efficiently reduced G. lamblia infection in mice. More specifically, excretion of Giardia cysts were reduced significantly in probiotic-treated groups, and resolution of infection was observed by day 21 post-inoculation. It was also observed that the lactobacillus count increased tremendously and continuously in faeces of all probiotic-fed mice, and was significantly higher as compared with that in control mice. Histological analysis of microvilli membrane integrity revealed that probiotic administration also protected mice against parasite-induced mucosal damage, whereas Giardia-infected mice had severe villous atrophy, oedema, vacuolation and ileitis. Immunologically, the anti-Giardia serum IgG level was not stimulated significantly by probiotic treatment administered both prior to and simultaneous with Giardia infection, but remained high after the infection peak. Taken together, the data demonstrates the anti-giardial effect of the probiotic in vivo by modulation of the intestinal epithelial cells, inhibiting the colonization of Giardia trophozoites and thereby reducing the severity of Giardia infection.
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3

Han, Jian, and Lesley J. Collins. "Reconstruction of Sugar Metabolic Pathways of Giardia lamblia." International Journal of Proteomics 2012 (October 18, 2012): 1–9. http://dx.doi.org/10.1155/2012/980829.

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Giardia lamblia is an “important” pathogen of humans, but as a diplomonad excavate it is evolutionarily distant from other eukaryotes and relatively little is known about its core metabolic pathways. KEGG, the widely referenced site for providing information of metabolism, does not yet include many enzymes from Giardia species. Here we identify Giardia’s core sugar metabolism using standard bioinformatic approaches. By comparing Giardia proteomes with known enzymes from other species, we have identified enzymes in the glycolysis pathway, as well as some enzymes involved in the TCA cycle and oxidative phosphorylation. However, the majority of enzymes from the latter two pathways were not identifiable, indicating the likely absence of these functionalities. We have also found enzymes from the Giardia glycolysis pathway that appear more similar to those from bacteria. Because these enzymes are different from those found in mammals, the host organisms for Giardia, we raise the possibility that these bacteria-like enzymes could be novel drug targets for treating Giardia infections.
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4

Touz, María, Constanza Feliziani, and Andrea Rópolo. "Membrane-Associated Proteins in Giardia lamblia." Genes 9, no. 8 (August 10, 2018): 404. http://dx.doi.org/10.3390/genes9080404.

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The manner in which membrane-associated proteins interact with the membrane defines their subcellular fate and function. This interaction relies on the characteristics of the proteins, their journey after synthesis, and their interaction with other proteins or enzymes. Understanding these properties may help to define the function of a protein and also the role of an organelle. In the case of microorganisms like protozoa parasites, it may help to understand singular features that will eventually lead to the design of parasite-specific drugs. The protozoa parasite Giardia lamblia is an example of a widespread parasite that has been infecting humans and animals from ancestral times, adjusting itself to the changes of the environment inside and outside the host. Several membrane-associated proteins have been posted in the genome database GiardiaDB, although only a few of them have been characterized. This review discusses the data regarding membrane-associated proteins in relationship with lipids and specific organelles and their implication in the discovery of anti-giardial therapies.
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5

Crossley, R., and D. Holberton. "Assembly of 2.5 nm filaments from giardin, a protein associated with cytoskeletal microtubules in Giardia." Journal of Cell Science 78, no. 1 (October 1, 1985): 205–31. http://dx.doi.org/10.1242/jcs.78.1.205.

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The giardins are a family of approximately 30000 Mr structural proteins found in microribbons attached to microtubules in the disc cytoskeleton of Giardia. After examining the solubility of giardins in various agents, a method has been developed to extract these polypeptides and subsequently precipitate them selectively. The giardin chains are soluble in 10 mM-HEPES/EDTA buffer at high pH and low ionic strength, but become insoluble in 10 mM-MES/EDTA buffer at pH 6.7 when the ionic strength is raised above 50 mM salt. By dialysing giardin extracts in turn against dissociating and reassembly buffers, the purification is obtained of a subset of giardin chains identified by sodium dodecyl sulphate/polyacrylamide gel electrophoresis as the cytoskeleton bands 14a, 14b and 15. The structures forming under assembly conditions are all composed of fine filaments, 2–3 nm in diameter. Filaments after the first cycle of assembly are found in bundles, narrow ribbons of two or three filaments, and large ordered tactoids. Assembly after a second cycle of solubilization yields a more uniform population of long ribbons. Both the tactoids and the second cycle ribbons are transversely banded at the 15 nm interval characteristic of microribbons in the cytoskeleton. Filaments in the tactoids are precisely placed at a centre-to-centre separation of 2.5 nm. Other structural features of the tactoids are discussed in relation to the association behaviour and possible dimensions of the giardin molecular subunit.
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6

Wei, Chao Jun, Xi Feng Tian, Rodney D. Adam, and Si Qi Lu. "Giardia lamblia: Intracellular localization of alpha8-giardin." Experimental Parasitology 126, no. 4 (December 2010): 489–96. http://dx.doi.org/10.1016/j.exppara.2010.05.028.

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7

Heyworth, Martin F., Jason D. Foell, and Thomas W. Sell. "Giardia muris:Evidence for a β-Giardin Homologue." Experimental Parasitology 91, no. 3 (March 1999): 284–87. http://dx.doi.org/10.1006/expr.1998.4367.

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8

de Gentile, Ludovic. "Giardia duodenalis, agent de la giardiase." EMC - Biologie Médicale 1, no. 1 (January 2006): 1–3. http://dx.doi.org/10.1016/s2211-9698(06)76277-x.

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9

Nixon, Julie E. J., Amy Wang, Jessica Field, Hilary G. Morrison, Andrew G. McArthur, Mitchell L. Sogin, Brendan J. Loftus, and John Samuelson. "Evidence for Lateral Transfer of Genes Encoding Ferredoxins, Nitroreductases, NADH Oxidase, and Alcohol Dehydrogenase 3 from Anaerobic Prokaryotes to Giardialamblia and Entamoebahistolytica." Eukaryotic Cell 1, no. 2 (April 2002): 181–90. http://dx.doi.org/10.1128/ec.1.2.181-190.2002.

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ABSTRACT Giardia lamblia and Entamoeba histolytica are amitochondriate, microaerophilic protists which use fermentation enzymes like those of bacteria to survive anaerobic conditions within the intestinal lumen. Genes encoding fermentation enzymes and related electron transport peptides (e.g., ferredoxins) in giardia organisms and amebae are hypothesized to be derived from either an ancient anaerobic eukaryote (amitochondriate fossil hypothesis), a mitochondrial endosymbiont (hydrogen hypothesis), or anaerobic bacteria (lateral transfer hypothesis). The goals here were to complete the molecular characterization of giardial and amebic fermentation enzymes and to determine the origins of the genes encoding them, when possible. A putative giardia [2Fe-2S]ferredoxin which had a hypothetical organelle-targeting sequence at its N terminus showed similarity to mitochondrial ferredoxins and the hydrogenosomal ferredoxin of Trichomonas vaginalis (another luminal protist). However, phylogenetic trees were star shaped, with weak bootstrap support, so we were unable to confirm or rule out the endosymbiotic origin of the giardia [2Fe-2S]ferredoxin gene. Putative giardial and amebic 6-kDa ferredoxins, ferredoxin-nitroreductase fusion proteins, and oxygen-insensitive nitroreductases each tentatively supported the lateral transfer hypothesis. Although there were not enough sequences to perform meaningful phylogenetic analyses, the unique common occurrence of these peptides and enzymes in giardia organisms, amebae, and the few anaerobic prokaryotes suggests the possibility of lateral transfer. In contrast, there was more robust phylogenetic evidence for the lateral transfer of G. lamblia genes encoding an NADH oxidase from a gram-positive coccus and a microbial group 3 alcohol dehydrogenase from thermoanaerobic prokaryotes. In further support of lateral transfer, the G. lamblia NADH oxidase and adh3 genes appeared to have an evolutionary history distinct from those of E. histolytica.
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10

Abbasi, Elnaz, Alireza Amouzandeh-Nobaveh, and Ehsanollah Ghaznavi-Rad. "The Frequency of the Intestinal Parasites Giardia Lamblia and Entamoeba Histolytica in Pediatric Diarrhea Specimens from Central Iran." Open Microbiology Journal 14, no. 1 (March 13, 2020): 53–56. http://dx.doi.org/10.2174/1874285802014010053.

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Introduction: Intestinal parasitic infections, particularly those caused by Giardia lamblia, are among the major health problems that exist worldwide, especially in developing countries. This study aimed to investigate the prevalence of the intestinal parasites Giardia lamblia and Entamoeba histolytica that were isolated from samples of infectious diarrhea in pediatric patients from Central Iran. Methods: This descriptive cross-sectional study included 230 samples of infectious diarrhea that were collected from May 2015 to February 2016. Direct observation, the formalin-ether sedimentation method and the technique using the Polymerase Chain Reaction (PCR) of β-giardin and EH primers were used for the identification of Giardia lamblia and Entamoeba histolytica. Results: Out of 230 samples of infectious diarrhea, five cases (2.1%) of Giardia lamblia and no cases (0%) of Entamoeba histolytica were identified using the formalin-ether sedimentation method and the same result were obtained using PCR technique. Of the five patients who had Giardia lamblia, three (60%) were male and two (40%) were female. The most common clinical symptoms in these patients were stomach ache and diarrhea (100%) and mucus in the stool (80%). Conclusion: Giardia lamblia was introduced as a parasitic agent causing diarrhea from Central Iran. The results indicate that pediatricians and, even more importantly, experts in laboratories should pay special attention to the identification of this parasite to treat the patients as effectively and as quickly as possible.
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Fernández-Lainez, Cynthia, Ignacio de la Mora-de la Mora, Itzhel García-Torres, Sergio Enríquez-Flores, Luis Flores-López, Pedro Gutiérrez-Castrellón, Lilian Yépez-Mulia, Felix Matadamas-Martínez, Paul de Vos, and Gabriel López-Velázquez. "Multilevel Approach for the Treatment of Giardiasis by Targeting Arginine Deiminase." International Journal of Molecular Sciences 22, no. 17 (August 31, 2021): 9491. http://dx.doi.org/10.3390/ijms22179491.

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Giardiasis represents a latent problem in public health due to the exceptionally pathogenic strategies of the parasite Giardia lamblia for evading the human immune system. Strains resistant to first-line drugs are also a challenge. Therefore, new antigiardial therapies are urgently needed. Here, we tested giardial arginine deiminase (GlADI) as a target against giardiasis. GlADI belongs to an essential pathway in Giardia for the synthesis of ATP, which is absent in humans. In silico docking with six thiol-reactive compounds was performed; four of which are approved drugs for humans. Recombinant GlADI was used in enzyme inhibition assays, and computational in silico predictions and spectroscopic studies were applied to follow the enzyme’s structural disturbance and identify possible effective drugs. Inhibition by modification of cysteines was corroborated using Ellman’s method. The efficacy of these drugs on parasite viability was assayed on Giardia trophozoites, along with the inhibition of the endogenous GlADI. The most potent drug against GlADI was assayed on Giardia encystment. The tested drugs inhibited the recombinant GlADI by modifying its cysteines and, potentially, by altering its 3D structure. Only rabeprazole and omeprazole decreased trophozoite survival by inhibiting endogenous GlADI, while rabeprazole also decreased the Giardia encystment rate. These findings demonstrate the potential of GlADI as a target against giardiasis.
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12

Priest, Jeffrey W., Delynn M. Moss, Govinda S. Visvesvara, Cara C. Jones, Anna Li, and Judith L. Isaac-Renton. "Multiplex Assay Detection of Immunoglobulin G Antibodies That Recognize Giardia intestinalis and Cryptosporidium parvum Antigens." Clinical and Vaccine Immunology 17, no. 11 (September 28, 2010): 1695–707. http://dx.doi.org/10.1128/cvi.00160-10.

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ABSTRACT Giardiasis and cryptosporidiosis are common enteric parasitic diseases that have similar routes of transmission. In this work, we have identified epitopes within the Giardia variant-specific surface protein (VSP) sequences that are recognized by IgG antibodies from 13 of 14 (93%) sera from patients with stool-confirmed giardiasis. The conserved epitopes are shared among VSPs from both of the assemblages that commonly infect humans, and they are likely to be structural, as both sodium dodecyl sulfate treatment and dithiothreitol reduction decrease antibody recognition. In a multiplex bead assay (MBA), we used three VSP fragments from an assemblage A Giardia strain, three VSP fragments from assemblage B strains, and the α-1 giardin structural antigen to detect IgG antibodies to Giardia and used the recombinant 17- and 27-kDa antigens to simultaneously detect IgG antibodies to Cryptosporidium. The MBA differentiated between sera from Giardia and Cryptosporidium outbreaks and also identified a giardiasis outbreak that may have included cryptosporidiosis cases. Approximately 40% of cryptosporidiosis outbreak samples had high MBA responses for both the 27- and 17-kDa antigens, while <10% of nonoutbreak and giardiasis outbreak samples had high responses. At least 60% of giardiasis outbreak samples were positive for antibodies to multiple Giardia antigens, while ≤12% of nonoutbreak samples and samples from U.S. and British Columbia cryptosporidiosis outbreaks met our definition for Giardia seropositivity. A MBA using multiple parasite antigens may prove useful in the epidemiologic analysis of future waterborne or food-borne outbreaks of diarrheal disease.
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13

Gultekin, Mehmet, Kerem Ural, Nuram Aysul, Adnam Ayan, Canberk Balikci, Songul Toplu, and Gurkan Akyildiz. "Prevalence and Molecular Characterization of Giardia duodenalis in Calves in Turkey." Acta Scientiae Veterinariae 45, no. 1 (June 20, 2017): 6. http://dx.doi.org/10.22456/1679-9216.80032.

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Background: Giardia duodenalis (G. duodenalis) is an ubiquitous, flagellated intestinal protozoan with major public health significance worldwide. Limited data are available on the epidemiology of G. duodenalis in dairy cattle from Turkey. Determining the zoonotic potential of the Giardia infection requires molecular characterization. The aim of the present study was to investigate the prevalence and to molecularly characterize G. duodenalis in calves less than three months of age in Aydin, Aegean region of Turkey.Materials, Methods & Results: The study was conducted on different dairy farms in the south-western part of the Turkey, Aegean Region, Aydin. A total of 198 Holstein Friesian calves less than three months of age, of both sexes were enrolled into the study. Faecal samples from each calf were collected manually from the rectum using a disposable latex glove. The consistency of collected samples was recorded as diarrhoeic or non-diarrhoeic. Diagnosis of G. duodenalis infection was made microscopically by detection of cysts in the faecal samples. One hundred and sixteen (58.5%) of the 198 faecal samples were diarrheic. Giardia cysts were found in 27 (23.28%) of the diarrheic samples and in 8 (9.76%) of nondiarrheic samples (P < 0.05). The overall prevalence of giardiosis in calves was determined as 17.67%. The prevalence of Giardia genotypes was identified by DNA sequence analysis of the beta-giardin gene for every PCR positive sample. The beta-giardin nested PCR assay was revealed assemblage A and sub-genotype A3 was detected in all of 35 samples (100%).Discussion: The highest prevalence of Giardia infection in calves is reported at the age between 1 and 6 months, and the prevalence shows decreased rate from the age of 6 months. The present study was conducted in Aydin, a province of south-western Turkey in the Aegean Region, and the overall prevalence from a total of 198 dairy calves was 17.67%. The prevalence rate in calves with diarrhoea was higher and reached up to 23.28%, whereas it was 9.76% in non-diarrhoeic calves. A prevalence study with molecular characterization of G. duodenalis isolates in cattle has not yet been reported from Turkey. Molecular studies have shown that mostly assemblage E predominates in cattle, but recent studies denoted that assemblage A is increasingly being detected and might be more widespread than expected before. In the present study, Giardia positive samples identified with a beta-giardin nested PCR assay. The sub-genotype A3 was identified in all samples. The same sub-genotype was identified in human and dog samples from different countries. Furthermore, sub-genotype A3 was found in humans and dogs from Turkey. In this context, results of the present study suggested an important role of calves as potential reservoirs of human infections in Turkey. In conclusion, epidemiological data revealed that G. duodenalis infection is frequent in calves with diarrhoea in Aydin, Turkey. The presence of the potentially zoonotic sub-genotype A3 and high prevalence of Giardia infection in diarrheic calves indicated the importance of treatment and necessary preventative measures. Further studies in human and animal populations living in this region are warranted regarding the zoonotic epidemiology of Giardia duodenalis.
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Utaaker, Kjersti Selstad, Himanshu Joshi, Anil Kumar, Suman Chaudhary, and Lucy J. Robertson. "Occurrence of Cryptosporidium and Giardia in potable water sources in Chandigarh, Northern India." Journal of Water Supply: Research and Technology-Aqua 68, no. 6 (July 1, 2019): 483–94. http://dx.doi.org/10.2166/aqua.2019.157.

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AbstractContamination with Cryptosporidium and Giardia from drinking water sources in a city in Northern India was assessed. A protocol modified from a standard ISO protocol, which includes filtration, concentration, separation and detection steps, was tested and showed comparable recovery efficiencies (Giardia mean = 77.4%, Cryptosporidium mean = 61.8% from the modified protocol, compared with Giardia mean = 61.6%, Cryptosporidium mean = 69% from the ISO protocol) at a substantial cost reduction. This protocol was used for analysing 71 samples of potable water from different areas of Chandigarh, where sampling locations were divided into groups according to the population density, which also partially equates with the level of infrastructure. Samples were collected during (n = 29) and outside the monsoon season (n = 42). Of all samples analysed, 16 (22.5%) were Cryptosporidium- and/or Giardia-positive. Parasites per sample were low (1–10 (oo)cysts per 10 L), although one sample contained large numbers of Giardia cysts (>1,000). Polymerase chain reaction analyses on the small subunit ribosomal ribonucleic acid (SSU rRNA), triose-phosphate isomerase (tpi), glutamate dehydrogenase (gdh) and beta-giardin (bg) gene sequences on Giardia-positive samples and SSU rRNA on Cryptosporidium-positive samples tended to be unsuccessful, although Giardia cysts of Assemblages B and C were identified. No association with the season was detected, but an association with the location of water supply was identified. Samples from areas with the lowest infrastructure were not associated with higher levels of contamination, but samples from the middle level were significantly more likely to be contaminated than those from the highest level of infrastructure. Results indicate that even in a city with a well-developed infrastructure, the contamination of potable water with protozoan parasites remains a public health risk.
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Maux, M., I. Bertrand, C. Gantzer, and J. Schwartzbrod. "Estimating Giardia cyst viability using RT-PCR." Water Supply 2, no. 3 (July 1, 2002): 107–15. http://dx.doi.org/10.2166/ws.2002.0092.

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The aim of this work was to evaluate the use of molecular techniques for the detection of viable Giardia cysts in the environment to assess public health issues. Three target genes were selected: the heat shock protein gene, HSP70, which is expressed in response to stress; the giardin gene, which encodes a structural protein; and, alcohol dehydrogenase E (ADHE), a novel gene encoding an enzyme involved in the metabolism of energy. We tested the efficiency of five protocols for the extraction of either genomic DNA or total RNA from Giardia cysts: two of these protocols were previously cited in the literature and three consisted of commercial DNA extraction kits. The brands of enzyme were determined according to the primers chosen and the amplification conditions were optimised: 2.5 mM MgCl2, 0.5 mM primers and 60°C for annealing temperature. A semi-nested PCR method and an RT semi-nested PCR procedure were developed to detect mRNA from these three genes and to estimate the viability of Giardia cysts.
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Siddiq, A., T. Allain, G. Dong, M. Olivier, and A. Buret. "A202 ROLE OF EXTRACELLULAR VESICLES IN GIARDIA-MICROBIOTA INTERACTIONS." Journal of the Canadian Association of Gastroenterology 4, Supplement_1 (March 1, 2021): 226–28. http://dx.doi.org/10.1093/jcag/gwab002.200.

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Abstract Background Extracellular vesicles (EVs) have emerged as important mediators of host-parasite interactions. Studies in various parasites have shown that EVs have important roles in pathogenesis. The protozoan parasite Giardia duodenalis, which causes diarrheal disease, produces EVs in response to changes in the environment. However, their exact role in the pathogenesis of giardiasis remains unclear. In this study, we investigate the effects of Giardia EVs on the gut commensal bacteria. EVs mediated disruption of the microbiota represents a novel mechanism that has not been investigated before. Aims We hypothesize that Giardia EVs contain virulence factors that will modify the growth and behavior of commensal bacteria. Based on our hypothesis, the study has three aims: 1. Quantify and characterize the EVs produced by Giardia under varying conditions. 2. Examine the effects of Giardia EVs on commensal bacteria. 3. Identify proteins and virulence factors in Giardia EVs using proteomics. Methods G. duodenalis (isolate NF) was exposed to bile or left untreated and the EVs were isolated using Exo-Easy Maxi Kit (Qiagen). The isolated EVs were characterized using Nanosight track analysis (NTA) and transmission electron microscopy. To examine the effects of EVs on bacteria, we used a lab strain E.coli HB101 and human isolate E. cloacae. The bacteria were incubated with Giardia EVs and their growth rate was monitored using a bacterial kinetics assay. The swimming motility of bacteria exposed to Giardia EVs was assessed on a 0.3% agar. Additionally, the ability of the EVs treated bacteria to adhere to epithelial cells was also examined. Proteomic analysis of EVs was conducted using liquid chromatography with tandem mass spectrometry. Results Results indicate that bile treated Giardia trophozoites produce more EVs as compared to untreated trophozoites. Giardia EVs exerted bacteriostatic effects on E.coli HB101 and E. cloacae. Additionally, Giardia EVs significantly increased the swimming motility of both E.coli HB101 and E. cloacae as well as their adhesion to the intestinal epithelial cells. Finally, proteomic analysis of EVs revealed the presence of well-characterized Giardia virulence factors such as cysteine proteases, tenascins, variant surface proteins as well as metabolic enzymes such as arginine deaminase and ornithine carbamoyltransferase. Conclusions Our research highlights a novel mechanism of Giardia’s interaction with commensal bacteria. Our results indicate that Giardia can release EVs in response to changes in the environment. These EVs also contain virulence factors that can modify the growth and behavior of commensal bacteria. These effects may have significant implications in disease pathophysiology. The results of the study can also be applied to other parasitic diseases where the production of EVs has been shown to play a role in the pathogenesis process. Funding Agencies NSERC
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17

Crossley, R., J. Marshall, J. T. Clark, and D. V. Holberton. "Immunocytochemical differentiation of microtubules in the cytoskeleton of Giardia lamblia using monoclonal antibodies to alpha-tubulin and polyclonal antibodies to associated low molecular weight proteins." Journal of Cell Science 80, no. 1 (February 1, 1986): 233–52. http://dx.doi.org/10.1242/jcs.80.1.233.

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In interphase trophozoites of Giardia lamblia, separate populations of microtubules constitute the four parts of the mastigont apparatus: flagella, ventral disc, funis and median body. Antigenic differences between the tubules have been investigated by light and electron immunocytochemistry after labelling with two monoclonal antibodies to alpha-tubulin (YL 1/2 and YOL 1/34 clones), and with polyclonal antibodies to Giardia tubule-associated proteins. Both anti-tubulins stained all tubules after isolated structures were fixed in formaldehyde, but different patterns of reactivity were shown by unfixed tubules. YL 1/2 antibodies labelled flagellar axonemes and basal bodies, funis and median body tubules. Disc microtubules were mostly unlabelled, but the antibody bound strongly to the outer edge of the disc where the ends of tubules are embedded. YOL 1/34 antibodies stained disc tubules uniformly, and cross-reacted with the median body but not with tubules of axonemes, basal bodies or funis. Antibodies to giardins 14A and 14B (approximately 30 000 Mr filament-forming proteins) localized these proteins in the microribbons attached to disc microtubules. The median body was also labelled by anti-giardins, indicating an ontogenetic relationship between this organelle and the ventral disc. A second set of approximately 30 000 Mr proteins with no immunoreactivity to anti-giardin was found in flagella purified without removing flagellar membranes. These polypeptides were Triton-soluble and therefore probably originated from an extra-axonemal site. A rabbit antiserum to the labile flagellar proteins specifically stained the two ventral flagella, but not the other six flagella on this cell.
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18

Heresi, G., and T. G. Cleary. "Giardia." Pediatrics in Review 18, no. 7 (July 1, 1997): 243–47. http://dx.doi.org/10.1542/pir.18-7-243.

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19

Heresi, Gloria, and Thomas G. Cleary. "Giardia." Pediatrics In Review 18, no. 7 (July 1, 1997): 243–47. http://dx.doi.org/10.1542/pir.18.7.243.

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20

Bartelt, Luther A., and James A. Platts-Mills. "Giardia." Current Opinion in Infectious Diseases 29, no. 5 (October 2016): 502–7. http://dx.doi.org/10.1097/qco.0000000000000293.

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21

Hampton, Tracy. "Giardia." JAMA 298, no. 17 (November 7, 2007): 1998. http://dx.doi.org/10.1001/jama.298.17.1998-b.

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22

Liu, Hua, Ning Xu, Jianhai Yin, Zhongying Yuan, Yujuan Shen, and Jianping Cao. "Prevalence and multilocus genotyping of potentially zoonotic Giardia duodenalis in pigs in Shanghai, China." Parasitology 146, no. 9 (May 14, 2019): 1199–205. http://dx.doi.org/10.1017/s0031182019000349.

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AbstractGiardia duodenalis is a common intestinal parasite in humans and other mammals, and it causes major public and veterinary health problems worldwide. China is a major pig-raising country, and studies on Giardia in pigs have important public health significance. The present study was conducted to investigate the prevalence of Giardia and assess its genetic characterization. A total of 93 samples were collected from two farms in Shanghai. The presence of Giardia was determined using PCR and sequence analysis of glutamate dehydrogenase, beta-giardin and triose phosphate isomerase genes. The average prevalence of G. duodenalis infection was 26.88% (25/93) in the pigs, with 28.13% (18/64) in farm 1 vs 24.14% (7/29) in farm 2. All the PCR-positive products were successfully sequenced, and assemblage E was more prevalent. Zoonotic assemblages A and B and canine-specific assemblage C were identified in farm 1, whereas, only assemblage E was detected in farm 2. Interestingly, two pig isolates showed 100% homology with human-derived isolates from Australia and China at the bg and tpi loci respectively. Pigs infected with Giardia infect humans by polluting the environment; whether pigs are a potential environmental source of the human pathogen in China requires more epidemiological data.
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Winkworth, Cynthia L., James J. Learmonth, Christoph D. Matthaei, and Colin R. Townsend. "Molecular Characterization of Giardia Isolates from Calves and Humans in a Region in Which Dairy Farming Has Recently Intensified." Applied and Environmental Microbiology 74, no. 16 (June 20, 2008): 5100–5105. http://dx.doi.org/10.1128/aem.00232-08.

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ABSTRACT Giardiasis is a notifiable disease of high prevalence in New Zealand, but there is limited knowledge about the sources of Giardia duodenalis genotypes that can potentially cause human infections. Dairy calves are one environmental source of Giardia isolates, but it is unknown whether they harbor genotypes that are potentially capable of causing infections in humans. To address these questions, 40 Giardia isolates from calves and 30 from humans, living in the same region and collected over a similar period, were genotyped using the β-giardin gene. The G. duodenalis genetic assemblages A and B were identified from both calves and humans, and genotype comparisons revealed a substantial overlap of identical genotypes from the two hosts for both assemblages. Significantly, no assemblage E (the genotype commonly found in cattle elsewhere in the world) has been detected in New Zealand livestock to date. Given recent and rapid land use conversions to dairy farming in many South Island regions of New Zealand, an increasingly large concentration of domestic cattle harboring genotypes potentially capable of causing infections in humans is particularly concerning.
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24

Ouchene, N., N. A. Ouchene-Khelifi, M. Aissi, and A. Benakhla. "Prévalence de Cryptosporidium spp. et Giardia spp. chez les bovins de la région de Sétif au nord-est de l'Algérie." Revue d’élevage et de médecine vétérinaire des pays tropicaux 65, no. 3-4 (March 1, 2012): 53. http://dx.doi.org/10.19182/remvt.10122.

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La prévalence de Cryptosporidium spp. et de Giardia spp. a été étudiée dans 13 élevages bovins laitiers de la région de Sétif au nord-est de l’Algérie. Au total, 634 prélèvements de fèces ont été réalisés dont 302 chez des veaux et 332 chez des adultes. Cryptosporidium spp. a été identifié dans neuf élevages (69,2 p. 100) et dans 22 p. 100 de l’ensemble des animaux. Le parasite a été observé dans toutes les classes d’âge avec une prévalence plus élevée chez les veaux de 4 à 30 jours (p < 0,01). L’excrétion d’oocystes de Cryptosporidium spp. a été très significativement associée aux diarrhées, notamment chez les veaux âgés de moins de 30 jours (p < 0,001). D’autre part, Giardia spp. a été identifié dans 53,8 p. 100 des élevages et chez 13,8 p. 100 de l’ensemble des animaux. Contrairement à Cryptosporidium spp., l’infestation par Giardia spp. a semblé plus élevée chez les veaux plus âgés (4–12 mois) (p < 0,05). Aucune association significative n’a été signalée entre l’excrétion des kystes de Giar­dia spp. et le type des fèces. L’association des deux parasites a été trouvée chez 10,2 p. 100 de l’ensemble des veaux diarrhéiques. Ce travail montre l’importance de Cryptosporidium spp. et, pour la première fois en Algérie, de Giardia spp. chez les bovins laitiers de la région de Sétif.
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25

Andersen, Yolanda S., Frances D. Gillin, and Lars Eckmann. "Adaptive Immunity-Dependent Intestinal Hypermotility Contributes to Host Defense against Giardia spp." Infection and Immunity 74, no. 4 (April 2006): 2473–76. http://dx.doi.org/10.1128/iai.74.4.2473-2476.2006.

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ABSTRACT Humans infected with Giardia exhibit intestinal hypermotility, but the underlying mechanisms and functional significance are uncertain. Here we show in murine models of giardiasis that small-intestinal hypermotility occurs in a delayed fashion relative to peak parasite burden, is dependent on adaptive immune defenses, and contributes to giardial clearance.
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26

GEURDEN, T., B. LEVECKE, S. M. CACCIÓ, A. VISSER, G. DE GROOTE, S. CASAERT, J. VERCRUYSSE, and E. CLAEREBOUT. "Multilocus genotyping of Cryptosporidium and Giardia in non-outbreak related cases of diarrhoea in human patients in Belgium." Parasitology 136, no. 10 (July 27, 2009): 1161–68. http://dx.doi.org/10.1017/s0031182009990436.

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SUMMARYStool samples from Belgian patients suffering from abdominal pain and/or diarrhoea were examined for Cryptosporidium and Giardia. Cryptosporidium-positive samples were genotyped using the 70 kDa heat shock protein and the 60 kDa glycoprotein (GP60) genes: C. hominis was identified in 54·2% and C. parvum in 45·8% of the samples. Sequencing at the GP60 locus indicated that subgenotype IbA10G2 of C. hominis and subgenotype IIaA15G2R1 of C. parvum were the most prevalent, although several other subgenotypes were identified. For Giardia, sequencing at the β-giardin, triose phosphate isomerase (TPI) and glutamate dehydrogenase (GDH) genes revealed assemblage B as the most prevalent (74·4%) in human patients. A high degree of heterogeneity was found, especially on the β-giardin gene, and to a lesser extent on the GDH gene. Furthermore, using a novel species-specific PCR based on the TPI gene, mixed infections with both assemblage A and B were detected in a large number (32·4%) of human patients, which might have important epidemiological implications.
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27

Awad Awad, Mohymin Sabah, Tareq Rifaaht Minnat, and Anas A. Humadi. "Molecular Identification of Giardia Duodenalis Isolates from Children Stool in Diyala Province, Iraq." Pakistan Journal of Medical and Health Sciences 16, no. 7 (July 30, 2022): 377–81. http://dx.doi.org/10.53350/pjmhs22167377.

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One of the most prevalent human intestine protozoan parasites in the world, Giardia duodenalis is indigenous to every continent and infects a broad variety of animal hosts. The goal of the current study was to determine the prevalence of infection among Giardia duodenalis isolates from regional hospitals and private clinics in the Iraqi province of Diyala that would be the subject of additional genetic analysis. From the beginning of October 2021 to the end of January 2022, 100 children's stools were collected from hospitals and health centers in Diyala, Iraq. Additionally, Giardia duodenalis cysts and trophozoites were examined under the microscope, and DNA was extracted using Quick-DNA Fecal/Soil Microbe Kits. One hundred of the stools taken from youngsters show symptoms of diarrhoea, nausea, and abdominal pains Based on microscopic examination and PCR analysis, a 7 percent infection rate was discovered. In addition, genotyping was carried out utilizing G. duodenalis Tpi sequence analysis. The highest infection rate was 10 % in up 4-5 year category and the lowest infection rate 4.65% recorded in up one year category. While, the infection rate was highest in male samples 8.16% than female samples 5.88%. Regarding the giardiasis according to the house system, most people who were infected were living in the city centre at ratio 9.25%, followed by 4.34 % in persons living in the country side. On the other hand, the infection rate of Giardia infection was 6.89%,4.16% and 8.51% to the tap water, Reverse Osmosis(RO) water and filter water respectively. The findings of this study emphasize that area of study was G. duodenalis infection rate with source of infection route and water basis in children in this province. The genetic analysis of the region Beta-giardin and RH11 and TPIA in this study showed that this diagnosis of Giardia duodenalis was made after effective amplification of these regions. Keywords: Molecular, Infection rate, Risk factors, Giardia duodenalis.
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28

Lux, Laura, Rainer G. Ulrich, Sérgio Santos-Silva, João Queirós, Christian Imholt, Christian Klotz, Joana Paupério, et al. "Detection and Molecular Characterization of Giardia and Cryptosporidium spp. Circulating in Wild Small Mammals from Portugal." Animals 13, no. 3 (February 1, 2023): 515. http://dx.doi.org/10.3390/ani13030515.

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Cryptosporidium spp. and Giardia spp. are important diarrhea-causing protozoan parasites worldwide that exhibit broad host ranges. Wild small mammals can harbor host-adapted and potentially zoonotic species of both parasites. The aim of this study was to investigate Cryptosporidium spp. and Giardia spp. in wild rodents and shrews in Portugal, focusing on the protist’s occurrence and genetic diversity. Molecular screening by PCR at the small subunit (SSU) rRNA gene locus of 290 fecal samples from wood mice (Apodemus sylvaticus), southwestern water voles (Arvicola sapidus), Cabrera’s voles (Microtus cabrerae), Lusitanian pine voles (Microtus lusitanicus), Algerian mice (Mus spretus) and greater white-toothed shrews (Crocidura russula) in Northeast Portugal revealed the low occurrence of Cryptosporidium spp. (1%) and high occurrence of Giardia spp. (32.8%). The analysis revealed that “species” was the only significant factor associated with the increasing probability of Giardia spp. infection, with the highest prevalence reported in southwestern water voles and Lusitanian pine voles. Cryptosporidium and Giardia species determination at the SSU rRNA gene locus revealed C. muris and G. microti as the only circulating species, respectively. Subtyping of the glutamate dehydrogenase (gdh) and beta-giardin (bg) genes provided evidence of the high genetic diversity within the G. microti clade. This study suggests that rodent-adapted G. microti occurs to a large extent in cricetid hosts and supports the limited role of wild rodents and shrews as natural sources of human infections in Northeast Portugal regarding the investigated parasites. Moreover, this is the first record of G. microti in southwestern water voles, Lusitanian pine voles, Algerian mice, wood mice and Cabrera’s voles and C. muris in Cabrera’s voles. Finally, this study improves the database of sequences relevant for the sequence typing of G. microti strains and provides new insights about the epidemiology of Giardia spp. and Cryptosporidium spp. in wild rodents and shrews, two parasite genera of high importance for public and animal health.
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29

Dawson, Scott C., Meredith S. Sagolla, Joel J. Mancuso, David J. Woessner, Susan A. House, Lillian Fritz-Laylin, and W. Zacheus Cande. "Kinesin-13 Regulates Flagellar, Interphase, and Mitotic Microtubule Dynamics in Giardia intestinalis." Eukaryotic Cell 6, no. 12 (August 31, 2007): 2354–64. http://dx.doi.org/10.1128/ec.00128-07.

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ABSTRACT Microtubule depolymerization dynamics in the spindle are regulated by kinesin-13, a nonprocessive kinesin motor protein that depolymerizes microtubules at the plus and minus ends. Here we show that a single kinesin-13 homolog regulates flagellar length dynamics, as well as other interphase and mitotic dynamics in Giardia intestinalis, a widespread parasitic diplomonad protist. Both green fluorescent protein-tagged kinesin-13 and EB1 (a plus-end tracking protein) localize to the plus ends of mitotic and interphase microtubules, including a novel localization to the eight flagellar tips, cytoplasmic anterior axonemes, and the median body. The ectopic expression of a kinesin-13 (S280N) rigor mutant construct caused significant elongation of the eight flagella with significant decreases in the median body volume and resulted in mitotic defects. Notably, drugs that disrupt normal interphase and mitotic microtubule dynamics also affected flagellar length in Giardia. Our study extends recent work on interphase and mitotic kinesin-13 functioning in metazoans to include a role in regulating flagellar length dynamics. We suggest that kinesin-13 universally regulates both mitotic and interphase microtubule dynamics in diverse microbial eukaryotes and propose that axonemal microtubules are subject to the same regulation of microtubule dynamics as other dynamic microtubule arrays. Finally, the present study represents the first use of a dominant-negative strategy to disrupt normal protein function in Giardia and provides important insights into giardial microtubule dynamics with relevance to the development of antigiardial compounds that target critical functions of kinesins in the giardial life cycle.
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30

Wu, Sheng, Weida Pan, Xianli Shi, Auwalu Yusuf Abdullahi, Zhen Wang, Xingang Yu, Biao Jiang, Kangxin Li, Chang Xu, and Guoqing Li. "Immunolocalization of α18- and α12-giardin in Giardia lamblia trophozoites." Parasitology Research 115, no. 11 (July 28, 2016): 4183–87. http://dx.doi.org/10.1007/s00436-016-5194-z.

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31

Ali, Syed A., and David R. Hill. "Giardia intestinalis." Current Opinion in Infectious Diseases 16, no. 5 (October 2003): 453–60. http://dx.doi.org/10.1097/00001432-200310000-00012.

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32

Ali, Syed A., and David R. Hill. "Giardia intestinalis." Current Opinion in Internal Medicine 2, no. 6 (December 2003): 560–67. http://dx.doi.org/10.1097/00132980-200302060-00003.

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33

Ali, Syed A., and David R. Hill. "Giardia intestinalis." Current Opinion in Internal Medicine 2, no. 6 (December 2003): 560–67. http://dx.doi.org/10.1097/00132980-200312000-00003.

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34

Eagle, Kim, and Ann M. Dvorak. "Giardia lamblia." New England Journal of Medicine 328, no. 14 (April 8, 1993): 1010. http://dx.doi.org/10.1056/nejm199304083281406.

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35

SHEFF, BARBARA. "Giardia lamblia." Nursing 34, no. 4 (April 2004): 76. http://dx.doi.org/10.1097/00152193-200404000-00056.

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36

Pickering, Larry K., and Paul G. Engelkirk. "Giardia lamblia." Pediatric Clinics of North America 35, no. 3 (June 1988): 565–77. http://dx.doi.org/10.1016/s0031-3955(16)36472-0.

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37

Olson, M. E., H. Ceri, and D. W. Morck. "Giardia Vaccination." Parasitology Today 16, no. 5 (May 2000): 213–17. http://dx.doi.org/10.1016/s0169-4758(99)01623-3.

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38

Sheff, Barbara. "Giardia lamblia." Nursing (Ed. española) 23, no. 1 (January 2005): 56. http://dx.doi.org/10.1016/s0212-5382(05)71348-0.

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39

Bal�zs, Martha. "Giardia infection." Digestive Diseases and Sciences 34, no. 9 (September 1989): 1481–82. http://dx.doi.org/10.1007/bf01538093.

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40

Sudre, AP, D. Leles, MF Lima, and TCB Bomfim. "First molecular characterisation of Giardia duodenalis infection in dairy goats in Brazil." Veterinární Medicína 59, No. 6 (August 20, 2014): 283–92. http://dx.doi.org/10.17221/7572-vetmed.

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The aim of this study was to perform the first molecular genotyping of Giardia duodenalis from goats in Brazil, in order to assess the risk for zoonotic transmission. Samples were collected from two dairy goat farms (Saanen breed) located in the city of Niteroi in the state of Rio de Janeiro, Brazil. Goat faecal samples (n&nbsp;=&nbsp;58) were collected directly from the rectums of all animals up to one year of age and were subjected to centrifuge-flotation in sugar saturate solution. Nested-PCR and sequencing using &beta; -giardin and tpi gene targets was performed on positive samples. Seventeen out of fifty-eight (29.31%) faecal samples were positive for Giardia duodenalis cysts, all belonging to the same farm. Only eight isolates were successfully sequenced (eight samples for &beta;-giardin and four samples for tpi), all belonging to genotype E. Two types of sequences were identified for each locus within isolates from the current study, which exhibited sequence heterogeneity with variable numbers of single nucleotide polymorphisms. The present study contributes to a better understanding of the molecular epidemiology of this parasite. &nbsp;
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41

ANTHONY, J. P., L. FYFE, D. STEWART, and G. J. McDOUGALL. "Differential effectiveness of berry polyphenols as anti-giardial agents." Parasitology 138, no. 9 (August 2011): 1110–16. http://dx.doi.org/10.1017/s0031182011000825.

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SUMMARYFollowing previous work on the anti-giardial effect of blueberry polyphenols, a range of polyphenol-rich extracts from berries and other fruits was screened for their ability to kill Giardia duodenalis, an intestinal parasite of humans. Polyphenol-rich extracts were prepared from berries using solid-phase extraction and applied to trophozoites of Giardia duodenalis grown in vitro. All berry extracts caused inhibition at 166 μg gallic acid equivalents (GAE)/ml phenol content but extracts from strawberry, arctic bramble, blackberry and cloudberry were as effective as the currently used drug, metronidazole, causing complete trophozoite mortality in vitro. Cloudberry extracts were found to be the most effective causing effectively complete trophozoite mortality at 66 μg GAE/ml. The polyphenol composition of the more effective berry extracts suggested that the presence of ellagitannins could be an important factor. However, the potency of cloudberry could be related to high ellagitannin content but also to the presence of substantial amounts of unconjugated p-coumaric acid and benzoic acid. These in vitro effects occur at concentrations easily achievable in the gut after berry ingestion and we discuss the likelihood that berry extracts could be effective anti-giardial agents in vivo.
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42

Sulemana, Alimatu, Timothy A. Paget, and Edward L. Jarroll. "Commitment to cyst formation in Giardia." Microbiology 160, no. 2 (February 1, 2014): 330–39. http://dx.doi.org/10.1099/mic.0.072405-0.

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Giardia trophozoites differentiate into infectious cysts (encystment) in response to physiological stimuli; encystment is crucial for Giardia’s transmission, survival and pathogenesis. In vitro, Giardia encysts when bile sequesters lipids necessary for this lipid auxotroph, and in vivo they encyst to infect new hosts. In this study, we investigated, for the first time, commitment to encystment in Giardia using both molecular and cellular techniques. We show that after 3–6 h in inducing conditions, encysting trophozoites continue to encyst regardless of whether the inducing stimulus remains. We propose that a trophozoite’s inability to revert to a growing or dividing trophozoite represents a commitment to encystment. The onset of commitment correlated with the appearance of encystment specific vesicles (ESVs) and encystment specific protein synthesis. These observations suggest the involvement of regulatory pathways with the ability to ‘remember’ a transient signal long after its removal; a property that enables encysting trophozoites to complete the encystment process should the unfavourable triggering condition(s) change. The ability to form cysts in response to transient signals or, as we have highlighted in this paper, the ability of a small percentage of the population to form cysts without an inducer is vital for the maintenance of infection within populations.
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43

Groudan, Kevin, Kamesh Gupta, Jean Chalhoub, and Rohit Singhania. "Giardia lamblia Diagnosed Incidentally by Duodenal Biopsy." Journal of Investigative Medicine High Impact Case Reports 9 (January 2021): 232470962110016. http://dx.doi.org/10.1177/23247096211001649.

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Giardia lamblia (also referred to as Giardia intestinalis and Giardia duodenalis) is the most common intestinal parasite in the world, affecting approximately 200 million people annually. Symptoms of Giardia include foul-smelling diarrhea, abdominal cramping, bloating, gas, and nausea. Although usually self-limiting, Giardia can progress to dehydration, malnutrition, and failure to thrive, especially in immunocompromised individuals. Early diagnosis and treatment is imperative to prevent and control infection of Giardia. Infectious Disease Society of America diagnostic guidelines recommend obtaining stool studies to diagnose Giardia; when stool studies are negative but suspicion remains high, duodenal aspirate microscopy is the only alternative diagnostic strategy suggested. We report a patient diagnosed incidentally with Giardia from a duodenal biopsy specimen obtained during a workup for a gastrointestinal bleed. There are limited cases of Giardia diagnosed by duodenal biopsy reported in the literature. We review studies that suggest duodenal biopsy can be a very sensitive strategy for the diagnosis of Giardia.
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44

Walterspiel, Juan N., Ardythe L. Morrow, Larry K. Pickering, Guillermo M. Ruiz-Palacios, and M. Lourdes Guerrero. "Secretory Anti-Giardia lamblia Antibodies in Human Milk: Protective Effect Against Diarrhea." Pediatrics 93, no. 1 (January 1, 1994): 28–31. http://dx.doi.org/10.1542/peds.93.1.28.

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Objective. To determine whether anti-Giardia lamblia secretory IgA (sIgA) antibodies in human milk protect infants from acquisition of or symptoms associated with Giardia infection. Methods. One hundred ninety-seven Mexican mother/infant pairs were followed weekly from birth for diarrheal disease and feeding status. Infant stool specimens were collected weekly and were cultured for bacterial pathogens and tested for Giardia and rotavirus by enzyme-linked immunosorbent assay. Maternal milk samples were collected weekly for 1 month postpartum and monthly thereafter. To determine the protective effect of anti-Giardia sIgA in milk against infection and against diarrhea due to Giardia, milk samples from mothers of infected infants and appropriately matched controls were assayed for anti-Giardia sIgA by enzyme-linked immunosorbent assay. Results. Asymptomatic, infected infants ingested significantly (P = .046) higher amounts of milk anti-Giardia sIgA compared with symptomatic, infected infants. However, milk anti-Giardia sIgA concentrations did not differ between Giardia-infected and noninfected infants. Conclusion. The amount of anti-Giardia sIgA in human milk was associated with prevention of symptoms of diarrhea due to Giardia, but not with acquisition of the organism.
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45

Fernández-Lainez, Cynthia, Ignacio de la Mora-de la Mora, Sergio Enríquez-Flores, Itzhel García-Torres, Luis A. Flores-López, Pedro Gutiérrez-Castrellón, Paul de Vos, and Gabriel López-Velázquez. "The Giardial Arginine Deiminase Participates in Giardia-Host Immunomodulation in a Structure-Dependent Fashion via Toll-like Receptors." International Journal of Molecular Sciences 23, no. 19 (September 30, 2022): 11552. http://dx.doi.org/10.3390/ijms231911552.

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Beyond the problem in public health that protist-generated diseases represent, understanding the variety of mechanisms used by these parasites to interact with the human immune system is of biological and medical relevance. Giardia lamblia is an early divergent eukaryotic microorganism showing remarkable pathogenic strategies for evading the immune system of vertebrates. Among various multifunctional proteins in Giardia, arginine deiminase is considered an enzyme that plays multiple regulatory roles during the life cycle of this parasite. One of its most important roles is the crosstalk between the parasite and host. Such a molecular “chat” is mediated in human cells by membrane receptors called Toll-like receptors (TLRs). Here, we studied the importance of the 3D structure of giardial arginine deiminase (GlADI) to immunomodulate the human immune response through TLRs. We demonstrated the direct effect of GlADI on human TLR signaling. We predicted its mode of interaction with TLRs two and four by using the AlphaFold-predicted structure of GlADI and molecular docking. Furthermore, we showed that the immunomodulatory capacity of this virulent factor of Giardia depends on the maintenance of its 3D structure. Finally, we also showed the influence of this enzyme to exert specific responses on infant-like dendritic cells.
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46

Eckmann, Lars, and Frances D. Gillin. "Microbes and Microbial Toxins: Paradigms for Microbial- Mucosal Interactions I. Pathophysiological aspects of enteric infections with the lumen-dwelling protozoan pathogenGiardia lamblia." American Journal of Physiology-Gastrointestinal and Liver Physiology 280, no. 1 (January 1, 2001): G1—G6. http://dx.doi.org/10.1152/ajpgi.2001.280.1.g1.

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Giardia lamblia is one of the most important causes of waterborne diarrheal disease worldwide, and giardiasis is the most common protozoan infection of the human small intestine. Symptomatic infection is characterized by diarrhea, abdominal pain, and malabsorption, leading to malnutrition and weight loss, particularly in children. The pathogen resides strictly in the lumen of the small intestine, and infection is typically not accompanied by significant mucosal inflammation. Clinical and experimental studies indicate that B cell-dependent host defenses, particularly IgA, are important for controlling and clearing Giardia infection, although B cell-independent mechanisms also contribute to this outcome. In contrast to antigiardial host defenses, much less is known about the pathophysiological mechanisms underlying the clinical symptoms of giardiasis, partly because of the current lack of suitable model systems. In addition to being an important human enteric pathogen, Giardia is an interesting model organism for gaining basic insights into genetic innovations that led to evolution of eukaryotic cells, since it belongs to the earliest diverging eukaryotic lineage known. The completion of the giardial genome project will increase understanding of the basic biology of the protozoan and will help us to better understand host pathogen-interactions as a basis for developing new vaccination and therapeutic strategies.
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47

Hernandez, Yunuen, Max Shpak, Trevor T. Duarte, Tavis L. Mendez, Rosa A. Maldonado, Sukla Roychowdhury, Marcio L. Rodrigues, and Siddhartha Das. "Novel Role of Sphingolipid Synthesis Genes in Regulating Giardial Encystation." Infection and Immunity 76, no. 7 (April 21, 2008): 2939–49. http://dx.doi.org/10.1128/iai.00116-08.

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ABSTRACT Although encystation (cyst formation) is important for the survival of Giardia lamblia outside its human host, the molecular events that prompt encystation have not been fully elucidated. Here, we demonstrate that sphingolipids (SLs), which are important for the growth and differentiation of many eukaryotes, play key roles in giardial encystation. Transcriptional analyses showed that only three genes in the SL biosynthesis pathways are expressed and transcribed differentially in nonencysting and encysting Giardia trophozoites. While the putative homologues of giardial serine palmitoyltransferase (gSPT) subunit genes (gspt-1 and -2) are differentially expressed in nonencysting and encysting trophozoites, the giardial ceramide glucosyltransferase 1 gene (gglct-1) is transcribed only in encysting cells. l-Cycloserine, an inhibitor of gSPT, inhibited the endocytosis and endoplasmic reticulum/perinuclear targeting of bodipy-ceramide in trophozoites, and this could be reversed by 3-ketosphinganine. On the other hand, d-threo-1-phenyl-2-palmitoylamino-3-morpholino-1-propanol (PPMP), an inhibitor of glucosylceramide synthesis, blocked karyokinesis and reduced cyst production in culture. PPMP also altered the expression of cyst wall protein transcripts in encysting cells. Phylogenetic analyses revealed that the gspt genes are paralogs derived from an ancestral spt sequence that underwent gene duplication early in eukaryotic history. This ancestral sequence, in turn, was probably derived from prokaryotic aminoacyl transferases. In contrast, gglct-1 is found in both prokaryotes and eukaryotes without any evidence of gene duplication. These studies indicate that SL synthesis genes are involved in key events in giardial biology and could serve as potential targets for developing new therapies against giardiasis.
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48

Nohria, Anju, Rogelio A. Alonso, and Debra A. Peattie. "Identification and characterization of γ-giardin and the γ-giardin gene from Giardia lamblia." Molecular and Biochemical Parasitology 56, no. 1 (November 1992): 27–37. http://dx.doi.org/10.1016/0166-6851(92)90151-9.

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49

Yu, Xingang, Auwalu Yusuf Abdullahi, Sheng Wu, Weida Pan, Xianli Shi, Wei Hu, Liping Tan, Kangxin Li, Zhen Wang, and Guoqing Li. "Prokaryotic Expression of α-13 Giardin Gene and Its Intracellular Localization in Giardia lamblia." BioMed Research International 2017 (2017): 1–7. http://dx.doi.org/10.1155/2017/1603264.

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To study prokaryotic expression and subcellular localization of α-13 giardin in Giardia lamblia trophozoites, α-13 giardin gene was amplified and cloned into prokaryotic expression vector pET-28a(+). The positive recombinant plasmid was transformed into E. coli BL21(DE3) for expression by using IPTG and autoinduction expression system (ZYM-5052). The target protein was validated by SDS-PAGE and Western blotting and purified by Ni-NTA Resin. Rabbits were immunized with purified fusion proteins for preparation of polyclonal antibody; then the intracellular location of α-13 giardin was determined by fluorescence immunoassay. The results showed that the length of α-13 giardin gene was 1038 bp, encoding a polypeptide of 345 amino acids. The expressed product was a fusion protein with about 40 kDa largely present in soluble form. The target protein accounted for 21.0% of total proteins after being induced with IPTG, while it accounted for 28.8% with ZYM-5052. The anti-α13-giardin polyclonal antibody possessed good antigenic specificity as well as excellent binding activity with recombinant α-13 giardin. Immunofluorescence assays revealed that α-13 giardin was localized in the cytoplasm of G. lamblia trophozoite, suggesting that it is a cytoplasm-associated protein. The present study may lay a foundation for further functional research on α-13 giardin of G. lamblia.
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Suman, MSH, MM Alam, SB Pun, A. Khair, S. Ahmed, and RY Uchida. "PREVALENCE OF GIARDIA LAMBLIA INFECTION IN CHILDREN AND CALVES IN BANGLADESH." Bangladesh Journal of Veterinary Medicine 9, no. 2 (January 24, 2013): 177–82. http://dx.doi.org/10.3329/bjvm.v9i2.13474.

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Abstract:
Giardia lamblia is highly infectious protozoan parasite capable of causing gastrointestinal illness in both humans and animals. The objective of this study was to determine the prevalence of Giardia lamblia infection in children < 5 years old and calves. Enzyme Linked Immunosorbent Assay (ELISA) has been used for the detection of Giardia lamblia. A total of 266 children and 15 calves diarrheic fecal samples were tested for Giardia lamblia during January 2011 to May 2012. The prevalence of Giardia lamblia infection among children was 3.8% while 13.3% in calves. Giardia lamblia was highest in children between 24 and 60 months of age (8.7%). Giardia lamblia infection was higher in male (4.7%) than in female (2.0%). Male calves (14.3%) have slightly higher prevalence than female calves (12.5%). The highest prevalence (33.3%) of Giardia lamblia infection in calves was between the ages 6 and 9 months. This is the first study to determine the prevalence of Giardia lamblia infection in calves using ELISA method in Bangladesh. A larger scale study is needed for accurate estimates of prevalence of Giardia lamblia to undertake an appropriate control strategy in future.DOI: http://dx.doi.org/10.3329/bjvm.v9i2.13474
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