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Staffan G Svard - One of the best experts on this subject based on the ideXlab platform.
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transcriptional profiling of Giardia intestinalis in response to oxidative stress
International Journal for Parasitology, 2015Co-Authors: Showgy Y Maayeh, Livia Knorr, Staffan G SvardAbstract:Abstract Giardia intestinalis is a microaerophilic parasite that infects the human upper small intestine, an environment that is fairly aerobic with reactive oxygen species being produced to fight off the parasite. It is quite perplexing how Giardia, lacking conventional eukaryotic antioxidant machinery (e.g. catalase, superoxide dismutase and glutathione peroxidase), can cope with the oxidative stress in this environment. We used transcriptomics (RNA sequencing and quantitative PCR) to study Giardial gene expression changes in response to oxygen (O2; 1 h) and hydrogen peroxide (H2O2; 150 μM, 500 μM and 1 mM for 1 h). The results showed phenotypic and transcriptional differences between Giardia isolates of different genotypes (WB, assemblage A and GS, assemblage B), with GS being more tolerant to H2O2 and exhibiting higher basic transcript levels of antioxidant genes (e.g. NADH oxidase lateral transfer candidate, peroxiredoxin 1 (Prx1) and thioredoxin (Trx)-like proteins). Cysteine is a major antioxidant in Giardia and its role in oxidative defense could be highlighted here by the up-regulation of gene transcripts encoding the cysteine-rich variable surface proteins (VSPs) and high cysteine membrane proteins (HCMPs). Genes in the thioredoxin system (Prx1, Trx and Trx reductase) occupied a central role in the gene expression response to oxidative stress, together with genes encoding metabolic (NADPH-producing enzymes, glutathione and glycerol biosynthetic enzymes) and O2-consuming nitric oxide detoxification enzymes (e.g. nitroreductase, flavohemoprotein and a flavodiiron protein). This study reveals the intricate network of genes associated with the oxidative stress response in Giardia, and provides a stepping-stone towards future studies at the protein level.
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multilocus genotyping of human Giardia isolates suggests limited zoonotic transmission and association between assemblage b and flatulence in children
PLOS Neglected Tropical Diseases, 2011Co-Authors: Marianne Lebbad, Staffan G Svard, Ingvor Petersson, Lillemor Karlsson, Silvia Boterokleiven, Jan Andersson, Bo SvenungssonAbstract:Background: Giardia intestinalis is one of the most common diarrhea-related parasites in humans, where infection ranges from asymptomatic to acute or chronic disease. G. intestinalis consists of eight genetically distinct genotypes or assemblages, designated A-H, and assemblages A and B can infect humans. Giardiasis has been classified as a possible zoonotic disease but the role of animals in human disease transmission still needs to be proven. We tried to link different assemblages and sub-assemblages of G. intestinalis isolates from Swedish human patients to clinical symptoms and zoonotic transmission. Methodology/Principal Findings: Multilocus sequence-based genotyping of 207 human Giardia isolates using three gene loci: beta-giardin, glutamate dehydrogenase (gdh), and triose phosphate isomerase (tpi) was combined with assemblage-specific tpi PCRs. This analysis identified 73 patients infected with assemblage A, 128 with assemblage B, and six with mixed assemblages A+B. Multilocus genotypes (MLGs) were easily determined for the assemblage A isolates, and most patients with this genotype had apparently been infected through anthroponotic transmission. However, we also found evidence of limited zoonotic transmission of Giardia in Sweden, since a few domestic human infections involved the same assemblage A MLGs previously reported in Swedish cats and ruminants. Assemblage B was detected more frequently than assemblage A and it was also more common in patients with suspected treatment failure. However, a large genetic variability made determination of assemblage B MLGs problematic. Correlation between symptoms and assemblages was found only for flatulence, which was significantly more common in children less than six years of age infected with assemblage B. Conclusions/Significance: This study shows that certain assemblage A subtypes are potentially zoonotic and that flatulence is connected to assemblage B infections in young children. Determination of MLGs from assemblages A and B can be a valuable tool in outbreak situations and to help identify possible zoonotic transmission.
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Behind the smile: cell biology and disease mechanisms of Giardia species
Nature Reviews Microbiology, 2010Co-Authors: Johan Ankarklev, Jon Jerlström-hultqvist, Emma Ringqvist, Karin Troell, Staffan G SvardAbstract: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 . In addition to being a major worldwide contributor to diarrhoeal disease, Giardia intestinalis is a useful model system for studying basic eukaryotic cellular processes owing to its reduced complexity. Here, Svärd and colleagues review the recent advances in our understanding of Giardial cell biology and pathogenesis. Giardia intestinalis is recognized as a major worldwide contributor to diarrhoeal disease in humans and other mammals, but the disease mechanisms have been poorly understood until recently. Giardia spp. are some of the most divergent eukaryotes examined to date and provide unique opportunities for gaining basic insights into key pathways that characterize eukaryotic cells and also for identifying new molecular mechanisms. Cell differentiation in Giardia spp. involves two major developmental transitions: from the ingested, dormant cyst via the excyzoite to trophozoites, in a process known as excystation, and from the motile, replicating trophozoite back to the infective cyst, in a process known as encystation. Mitosomes in Giardia spp. are elongated, double-membraned organelles that are related to mitochondria, and their only known function is in the assembly of Fe–S clusters. Giardia spp., like all diplomonads, have two nuclei. These nuclei have been shown to be equivalent in size and in the amount of DNA that they contain, and both are transcriptionally active. Analyses of Giardia spp. genomes indicate that these organisms encode rudimentary forms of many cellular processes, with fewer subunits present in simplified cellular machineries, and have a limited metabolic repertoire with many bacterial-like enzymes that were introduced by horizontal gene transfer. The adhesive disc and the four flagella of the pathogen, together with differentiation and antigenic variation of the variant-specific surface proteins (VSPs), are the major virulence factors identified to date for Giardia spp. Epigenetic mechanisms, microRNAs and RNA interference have been shown to be important in the regulation of vsp gene expression. Several mechanisms (including epithelial-barrier dysfunction, apoptosis, diffuse shortening of microvilli, hypersecretion of Cl^− and inhibition of brush-border enzymes) have been proposed to be important for the induction of symptoms during Giardial infection, and the cause of Giardiasis is probably multifactorial.
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from mouse to moose multilocus genotyping of Giardia isolates from various animal species
Veterinary Parasitology, 2010Co-Authors: Marianne Lebbad, Staffan G Svard, Jan Andersson, Jens G Mattsson, Bodil Christensson, Bitte Ljungstrom, Annette BackhansAbstract:Giardia intestinalis is a protozoan parasite that consists of seven genetically distinct assemblages (A to G). Assemblage A and B parasites have been detected in a wide range of animals including humans, while the other assemblages (C to G) appear to have a narrower host range. However, the knowledge about zoonotic transmission of G. intestinalis is limited. To address this question, 114 Giardia isolates from various animals in Sweden including pets, livestock, wildlife and captive non-human primates were investigated by a sequence-based analysis of three genes (beta-giardin, glutamate dehydrogenase and triose phosphate isomerase). Assemblage A infections were detected in nine ruminants, five cats and one dog, while three sheep were infected with both assemblages A and E. Multilocus genotypes (MLGs) were defined for assemblage A, and three of these MLGs have previously been detected in Giardia isolates from humans. The newly described sub-assemblage AIII, until now reported mainly in wild hoofed animals, was found in one cat isolate. Assemblage B occurred in three monkeys, one guinea pig and one rabbit. The rabbit isolate exhibited sequences at all three loci previously detected in human isolates. The non-zoonotic assemblages C, D, E, F or G were found in the remaining 83 G. intestinalis isolates, which were successfully amplified and genotyped, generating a wide variety of both novel and known sub-genotypes. Double peaks in chromatograms were seen in assemblage B, C, D and E isolates but were never observed in assemblage A, F and G isolates, which can reflect differences in allelic sequence divergence. No evidence of genetic exchange between assemblages was detected. The study shows that multilocus genotyping of G. intestinalis is a highly discriminatory and useful tool in the determination of zoonotic sub-groups within assemblage A, but less valuable for subtyping assemblages B, C, D and E due to the high frequency of double peaks in the chromatograms. The obtained data also suggest that zoonotic transmission of assemblages A and B might occur to a limited extent in Sweden.
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novel protein disulfide isomerases from the early diverging protist Giardia lamblia
Journal of Biological Chemistry, 1999Co-Authors: Leigh A Knodler, Robert Noiva, Kapil Mehta, Michael J Mccaffery, Stephen B Aley, Staffan G Svard, Todd G Nystul, David S Reiner, Jeffrey D Silberman, Frances D GillinAbstract:Abstract Protein-disulfide isomerase is essential for formation and reshuffling of disulfide bonds during nascent protein folding in the endoplasmic reticulum. The two thioredoxin-like active sites catalyze a variety of thiol-disulfide exchange reactions. We have characterized three novel protein-disulfide isomerases from the primitive eukaryote Giardia lamblia. Unlike other protein-disulfide isomerases, the Giardial enzymes have only one active site. The active-site sequence motif in the Giardial proteins (CGHC) is characteristic of eukaryotic protein-disulfide isomerases, and not other members of the thioredoxin superfamily that have one active site, such as thioredoxin and Dsb proteins from Gram-negative bacteria. The three Giardial proteins have very different amino acid sequences and molecular masses (26, 50, and 13 kDa). All three enzymes were capable of rearranging disulfide bonds, and Giardial protein-disulfide isomerase-2 also displayed oxidant and reductant activities. Surprisingly, the three Giardial proteins also had Ca2+-dependent transglutaminase activity. This is the first report of protein-disulfide isomerases with a single active site that have diverse roles in protein cross-linking. This study may provide clues to the evolution of key functions of the endoplasmic reticulum in eukaryotic cells, protein disulfide formation, and isomerization.
Simone M Caccio - One of the best experts on this subject based on the ideXlab platform.
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Giardia and Cryptosporidium in cetaceans on the European Atlantic coast
Parasitology Research, 2015Co-Authors: Aurora Reboredo-fernández, Simone M Caccio, Elvira Ares-mazás, José A. Martínez-cedeira, Rafael Romero-suances, Hipólito Gómez-cousoAbstract:The occurrence of Giardia and Cryptosporidium was investigated in cetacean specimens stranded on the northwestern coast of Spain (European Atlantic coast) by analysis of 65 samples of large intestine from eight species. The parasites were identified by direct immunofluorescence antibody test (IFAT) and by PCR amplification of the β-giardin gene, the ITS1-5.8S-ITS2 region and the SSU-rDNA gene of Giardia and the SSU-rDNA gene of Cryptosporidium. Giardia and Cryptosporidium were detected in 7 (10.8 %) and 9 samples (13.8 %), respectively. In two samples, co-infection with both parasites was observed. Giardia duodenalis assemblages A, C, D and F, and Cryptosporidium parvum were identified. This is the first report of G. duodenalis in Balaenoptera acutorostrata , Kogia breviceps and Stenella coeruleoalba and also the first report of Cryptosporidium sp. in B. acutorostrata and of C. parvum in S. coeruleoalba and Tursiops truncatus . These results extend the known host range of these waterborne enteroparasites.
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a novel Giardia duodenalis assemblage a subtype in fallow deer
Journal of Parasitology, 2007Co-Authors: Marco Lalle, Frangipane A Di Regalbono, L Poppi, G Nobili, D Tonanzi, E Pozio, Simone M CaccioAbstract:The molecular identification of species and genotypes of Giardia spp. infecting wild mammals represents the most reliable tool to understand the role played by these animals as reservoirs of cysts infectious for human and other animals. Of 139 fecal samples collected from fallow deer (Dama dama L.) hunted in a Natural Reserve of northern Italy, the prevalence of Giardia sp. was 11.5% (16 of 139 animals), and it was higher in fawns than in older animals. Fragments of the β-giardin and triose phosphate isomerase (tpi) genes were successfully polymerase chain reaction amplified and sequenced from 8 isolates. No sequence variation was observed between isolates at the 2 genetic loci. Sequence and phylogenetic analyses identified a Giardia duodenalis subtype that clusters with assemblage A isolates and that shows homologies of 98 and 97% at the β-giardin and tpi loci, respectively, compared with the A1 subtype. Because the G. duodenalis subtype found in fecal samples of fallow deer has never been detected previ...
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genetic heterogeneity at the β giardin locus among human and animal isolates of Giardia duodenalis and identification of potentially zoonotic subgenotypes
International Journal for Parasitology, 2005Co-Authors: Marco Lalle, E Pozio, Gioia Capelli, Fabrizio Bruschi, Daniele Crotti, Simone M CaccioAbstract:Human Giardiasis, caused by the intestinal flagellate Giardia duodenalis, is considered a zoonotic infection, although the role of animals in the transmission to humans is still unclear. Molecular characterisation of cysts of human and animal origin represents an objective means to validate or reject this hypothesis. In the present work, cysts were collected in Italy from humans (n=37) and animals (dogs, one cat and calves, n=46), and were characterised by PCR amplification and sequencing of the β-giardin gene. As expected, only Assemblages A and B were identified among human isolates. The host-specific Assemblages C and D were found in the majority of dog isolates; however, 6 dog isolates were typed as Assemblage A. The cat-specific Assemblage F has been identified in the single feline isolate available. Among calf isolates, most were typed as Assemblages A (n=12) and B (n=5), whereas the host-specific Assemblage E was rarely found (n=3). Sequence heterogeneity in the β-giardin gene allowed a number of subgenotypes to be identified within Assemblage A (8 subgenotypes), B (6 subgenotypes), D (2 subgenotypes), and E (3 subgenotypes). Five of these subgenotypes, namely A1, A2, A3, A4 and B3, were found to be associated with infections of humans, of dogs and of calves; these data, therefore, supported the role of these animals as a source of infection for humans.
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genetic heterogeneity at the β giardin locus among human and animal isolates of Giardia duodenalis and identification of potentially zoonotic subgenotypes
International Journal for Parasitology, 2005Co-Authors: Marco Lalle, Edoardo Pozio, Gioia Capelli, Fabrizio Bruschi, Daniele Crotti, Simone M CaccioAbstract:Human Giardiasis, caused by the intestinal flagellate Giardia duodenalis, is considered a zoonotic infection, although the role of animals in the transmission to humans is still unclear. Molecular characterisation of cysts of human and animal origin represents an objective means to validate or reject this hypothesis. In the present work, cysts were collected in Italy from humans (n=37) and animals (dogs, one cat and calves, n=46), and were characterised by PCR amplification and sequencing of the beta-giardin gene. As expected, only Assemblages A and B were identified among human isolates. The host-specific Assemblages C and D were found in the majority of dog isolates; however, 6 dog isolates were typed as Assemblage A. The cat-specific Assemblage F has been identified in the single feline isolate available. Among calf isolates, most were typed as Assemblages A (n=12) and B (n=5), whereas the host-specific Assemblage E was rarely found (n=3). Sequence heterogeneity in the beta-giardin gene allowed a number of subgenotypes to be identified within Assemblage A (8 subgenotypes), B (6 subgenotypes), D (2 subgenotypes), and E (3 subgenotypes). Five of these subgenotypes, namely A1, A2, A3, A4 and B3, were found to be associated with infections of humans, of dogs and of calves; these data, therefore, supported the role of these animals as a source of infection for humans.
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Giardia cysts in wastewater treatment plants in italy
Applied and Environmental Microbiology, 2003Co-Authors: Simone M Caccio, Marzia De Giacomo, Francesca Anna Aulicino, Edoardo PozioAbstract:Reductions in annual rainfall in some regions and increased human consumption have caused a shortage of water resources at the global level. The recycling of treated wastewaters has been suggested for certain domestic, industrial, and agricultural activities. The importance of microbiological and parasitological criteria for recycled water has been repeatedly emphasized. Among water-borne pathogens, protozoa of the genera Giardia and Cryptosporidium are known to be highly resistant to water treatment procedures and to cause outbreaks through contaminated raw or treated water. We conducted an investigation in four wastewater treatment plants in Italy by sampling wastewater at each stage of the treatment process over the course of 1 year. The presence of the parasites was assessed by immunofluorescence with monoclonal antibodies. While Cryptosporidium oocysts were rarely observed, Giardia cysts were detected in all samples throughout the year, with peaks observed in autumn and winter. The overall removal efficiency of cysts in the treatment plants ranged from 87.0 to 98.4%. The removal efficiency in the number of cysts was significantly higher when the secondary treatment consisted of active oxidation with O2 and sedimentation instead of activated sludge and sedimentation (94.5% versus 72.1 to 88.0%; P = 0.05, analysis of variance). To characterize the cysts at the molecular level, the β-giardin gene was PCR amplified, and the products were sequenced or analyzed by restriction. Cysts were typed as assemblage A or B, both of which are human pathogens, stressing the potential risk associated with the reuse of wastewater.
Edoardo Pozio - One of the best experts on this subject based on the ideXlab platform.
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genetic heterogeneity at the β giardin locus among human and animal isolates of Giardia duodenalis and identification of potentially zoonotic subgenotypes
International Journal for Parasitology, 2005Co-Authors: Marco Lalle, Edoardo Pozio, Gioia Capelli, Fabrizio Bruschi, Daniele Crotti, Simone M CaccioAbstract:Human Giardiasis, caused by the intestinal flagellate Giardia duodenalis, is considered a zoonotic infection, although the role of animals in the transmission to humans is still unclear. Molecular characterisation of cysts of human and animal origin represents an objective means to validate or reject this hypothesis. In the present work, cysts were collected in Italy from humans (n=37) and animals (dogs, one cat and calves, n=46), and were characterised by PCR amplification and sequencing of the beta-giardin gene. As expected, only Assemblages A and B were identified among human isolates. The host-specific Assemblages C and D were found in the majority of dog isolates; however, 6 dog isolates were typed as Assemblage A. The cat-specific Assemblage F has been identified in the single feline isolate available. Among calf isolates, most were typed as Assemblages A (n=12) and B (n=5), whereas the host-specific Assemblage E was rarely found (n=3). Sequence heterogeneity in the beta-giardin gene allowed a number of subgenotypes to be identified within Assemblage A (8 subgenotypes), B (6 subgenotypes), D (2 subgenotypes), and E (3 subgenotypes). Five of these subgenotypes, namely A1, A2, A3, A4 and B3, were found to be associated with infections of humans, of dogs and of calves; these data, therefore, supported the role of these animals as a source of infection for humans.
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Giardia cysts in wastewater treatment plants in italy
Applied and Environmental Microbiology, 2003Co-Authors: Simone M Caccio, Marzia De Giacomo, Francesca Anna Aulicino, Edoardo PozioAbstract:Reductions in annual rainfall in some regions and increased human consumption have caused a shortage of water resources at the global level. The recycling of treated wastewaters has been suggested for certain domestic, industrial, and agricultural activities. The importance of microbiological and parasitological criteria for recycled water has been repeatedly emphasized. Among water-borne pathogens, protozoa of the genera Giardia and Cryptosporidium are known to be highly resistant to water treatment procedures and to cause outbreaks through contaminated raw or treated water. We conducted an investigation in four wastewater treatment plants in Italy by sampling wastewater at each stage of the treatment process over the course of 1 year. The presence of the parasites was assessed by immunofluorescence with monoclonal antibodies. While Cryptosporidium oocysts were rarely observed, Giardia cysts were detected in all samples throughout the year, with peaks observed in autumn and winter. The overall removal efficiency of cysts in the treatment plants ranged from 87.0 to 98.4%. The removal efficiency in the number of cysts was significantly higher when the secondary treatment consisted of active oxidation with O2 and sedimentation instead of activated sludge and sedimentation (94.5% versus 72.1 to 88.0%; P = 0.05, analysis of variance). To characterize the cysts at the molecular level, the β-giardin gene was PCR amplified, and the products were sequenced or analyzed by restriction. Cysts were typed as assemblage A or B, both of which are human pathogens, stressing the potential risk associated with the reuse of wastewater.
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sequence analysis of the β giardin gene and development of a polymerase chain reaction restriction fragment length polymorphism assay to genotype Giardia duodenalis cysts from human faecal samples
International Journal for Parasitology, 2002Co-Authors: Simone M Caccio, Marzia De Giacomo, Edoardo PozioAbstract:The flagellate parasite Giardia duodenalis is a major cause of diarrhoea in humans and in animals worldwide. Molecular techniques are particularly useful for studying the taxonomy, the population structure, the zoonotic potential of animal isolates, and the correlation between the genetic variability of the parasite and the range of clinical symptoms observed in humans. In this work, a new PCR assay that targets the beta-giardin gene was tested on 21 Giardia duodenalis reference strains representing Assemblages A, B and E, which are associated with infections of humans and other mammals. The assay was then applied to 30 faecal samples collected from Italian persons. The sequence analysis of 31 PCR products from both reference strains and clinical samples showed that each Assemblage is clearly distinct from the others on the basis of specific substitutions; the sequence diversity was approximately 5%, and all substitutions occurred at the third codon positions of the gene. The analysis of the intra-Assemblage variability allowed for the identification of three genotypes within Assemblage A, and of four genotypes within Assemblage B. Interestingly, two genotypes were identified only in the clinical samples and not in reference strains. Finally, a simple PCR-restriction fragment length polymorphism method was developed for the rapid discrimination of Assemblages and applied for the direct genetic analysis of cysts present in human faecal samples.
Bruno Polack - One of the best experts on this subject based on the ideXlab platform.
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bile salt hydrolase activities a novel target to screen anti Giardia lactobacilli
Frontiers in Microbiology, 2018Co-Authors: Thibault Allain, Soraya Chaouch, Myriam Thomas, Philippe Langella, Philippe Grellier, Bruno Polack, Marie-agnès Travers, Isabelle ValleAbstract:Giardia duodenalis is a protozoan parasite responsible for Giardiasis, a disease characterized by intestinal malabsorption, diarrhea and abdominal pain in a large number of mammal species. Giardiasis is one of the most common intestinal parasitic diseases in the world and thus a high veterinary, and public health concern. It is well established that some probiotic bacteria may confer protection against this parasite in vitro and in vivo and we recently documented the implication of bile-salt hydrolase (BSH)-like activities from strain La1 of Lactobacillus johnsonii as mediators of these effects in vitro. We showed that these activities were able to generate deconjugated bile salts that were toxic to the parasite. In the present study, a wide collection of lactobacilli strains from different ecological origins was screened to assay their anti-Giardial effects. Our results revealed that the anti-parasitic effects of some of the strains tested were well correlated with the expression of BSH-like activities. The two most active strains in vitro, La1 and Lactobacillus gasseri CNCM I-4884, were then tested for their capacity to influence G. duodenalis infection in a suckling mice model. Strikingly, only L. gasseri CNCM I-4884 strain was able to significantly antagonize parasite growth with a dramatic reduction of the trophozoites load in the small intestine. Moreover, this strain also significantly reduced the fecal excretion of Giardia cysts after 5 days of treatment, which could contribute to blocking the transmission of the parasite, in contrast of La1 where no effect was observed. This study represents a step further towards the development of new prophylactic strategies to combat G. duodenalis infection in both humans and animals.
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Bile Salt Hydrolase Activities: A Novel Target to Screen Anti-Giardia Lactobacilli?
Frontiers in Microbiology, 2018Co-Authors: Thibault Allain, Soraya Chaouch, Myriam Thomas, Philippe Langella, Philippe Grellier, Bruno Polack, Isabelle Florent, Marie-agnès Travers, Isabelle Valle, Luis Bermúdez-humaránAbstract:Giardia duodenalis is a protozoan parasite responsible for Giardiasis, a disease characterized by intestinal malabsorption, diarrhea and abdominal pain in a large number of mammal species. Giardiasis is one of the most common intestinal parasitic diseases in the world and thus a high veterinary, and public health concern. It is well-established that some probiotic bacteria may confer protection against this parasite in vitro and in vivo and we recently documented the implication of bile-salt hydrolase (BSH)-like activities from strain La1 of Lactobacillus johnsonii as mediators of these effects in vitro. We showed that these activities were able to generate deconjugated bile salts that were toxic to the parasite. In the present study, a wide collection of lactobacilli strains from different ecological origins was screened to assay their anti-Giardial effects. Our results revealed that the anti-parasitic effects of some of the strains tested were well-correlated with the expression of BSH-like activities. The two most active strains in vitro, La1 and Lactobacillus gasseri CNCM I-4884, were then tested for their capacity to influence G. duodenalis infection in a suckling mice model. Strikingly, only L. gasseri CNCM I-4884 strain was able to significantly antagonize parasite growth with a dramatic reduction of the trophozoites load in the small intestine. Moreover, this strain also significantly reduced the fecal excretion of Giardia cysts after 5 days of treatment, which could contribute to blocking the transmission of the parasite, in contrast of La1 where no effect was observed. This study represents a step toward the development of new prophylactic strategies to combat G. duodenalis infection in both humans and animals.
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Bile-Salt-Hydrolases from the Probiotic Strain Lactobacillus johnsonii La1 Mediate Anti-Giardial Activity in Vitro and in Vivo
Frontiers in Microbiology, 2018Co-Authors: Thibault Allain, Soraya Chaouch, Myriam Thomas, Isabelle Vallée, André Buret, Philippe Langella, Philippe Grellier, Bruno Polack, Luis Bermúdez-humarán, Isabelle FlorentAbstract:Giardia duodenalis (syn. G. lamblia, G. intestinalis) is the protozoan parasite responsible for Giardiasis, the most common and widely spread intestinal parasitic disease worldwide, affecting both humans and animals. After cysts ingestion (through either contaminated food or water), Giardia excysts in the upper intestinal tract to release replicating trophozoites that are responsible for the production of symptoms. In the gut, Giardia cohabits with the host's microbiota, and several studies have revealed the importance of this gut ecosystem and/or some probiotic bacteria in providing protection against G. duodenalis infection through mechanisms that remain incompletely understood. Recent findings suggest that Bile-Salt-Hydrolase (BSH)-like activities from the probiotic strain of Lactobacillus johnsonii La1 may contribute to the anti-Giardial activity displayed by this strain. Here, we cloned and expressed each of the three bsh genes present in the L. johnsonii La1 genome to study their enzymatic and biological properties. While BSH47 and BSH56 were expressed as recombinant active enzymes, no significant enzymatic activity was detected with BSH12. In vitro assays allowed determining the substrate specificities of both BSH47 and BSH56, which were different. Modeling of these BSHs indicated a strong conservation of their 3-D structures despite low conservation of their primary structures. Both recombinant enzymes were able to mediate anti-Giardial biological activity against Giardia trophozoites in vitro. Moreover, BSH47 exerted significant anti-Giardial effects when tested in a murine model of Giardiasis. These results shed new light on the mechanism, whereby active BSH derived from the probiotic strain Lactobacillus johnsonii La1 may yield anti-Giardial effects in vitro and in vivo. These findings pave the way toward novel approaches for the treatment of this widely spread but neglected infectious disease, both in human and in veterinary medicine.
Scott C Dawson - One of the best experts on this subject based on the ideXlab platform.
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novel structural components of the ventral disc and lateral crest in Giardia intestinalis
PLOS Neglected Tropical Diseases, 2011Co-Authors: Kari D Hagen, Susan A. House, Matthew P Hirakawa, Cindi L Schwartz, Jonathan K Pham, Michael J Cipriano, Moises J De La Torre, Gary Du, Brystal M Forsythe, Scott C DawsonAbstract:Giardia intestinalis is a ubiquitous parasitic protist that is the causative agent of Giardiasis, one of the most common protozoan diarrheal diseases in the world. Giardia trophozoites attach to the intestinal epithelium using a specialized and elaborate microtubule structure, the ventral disc. Surrounding the ventral disc is a less characterized putatively contractile structure, the lateral crest, which forms a continuous perimeter seal with the substrate. A better understanding of ventral disc and lateral crest structure, conformational dynamics, and biogenesis is critical for understanding the mechanism of Giardial attachment to the host. To determine the components comprising the ventral disc and lateral crest, we used shotgun proteomics to identify proteins in a preparation of isolated ventral discs. Candidate disc-associated proteins, or DAPs, were GFP-tagged using a ligation-independent high-throughput cloning method. Based on disc localization, we identified eighteen novel DAPs, which more than doubles the number of known disc-associated proteins. Ten of the novel DAPs are associated with the lateral crest or outer edge of the disc, and are the first confirmed components of this structure. Using Fluorescence Recovery After Photobleaching (FRAP) with representative novel DAP::GFP strains we found that the newly identified DAPs tested did not recover after photobleaching and are therefore structural components of the ventral disc or lateral crest. Functional analyses of the novel DAPs will be central toward understanding the mechanism of ventral disc-mediated attachment and the mechanism of disc biogenesis during cell division. Since attachment of Giardia to the intestine via the ventral disc is essential for pathogenesis, it is possible that some proteins comprising the disc could be potential drug targets if their loss or disruption interfered with disc biogenesis or function, preventing attachment.
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Imaging and Analysis of the Microtubule Cytoskeleton in Giardia
Methods in cell biology, 2010Co-Authors: Scott C Dawson, Susan A. HouseAbstract:Giardia intestinalis, a common parasitic protist, possesses a complex microtubule cytoskeleton critical for cellular function and transitioning between the cyst and trophozoite life cycle stages. The Giardial microtubule cytoskeleton is comprised of highly dynamic and stable structures. Novel microtubule structures include the ventral disc that is essential for the parasite's attachment to the intestinal villi to avoid peristalsis. The completed Giardia genome combined with new molecular genetic tools and live imaging will aid in the characterization and analysis of cytoskeletal dynamics in Giardia. Fundamental areas of Giardial cytoskeletal biology remain to be explored and knowledge of the molecular mechanisms of cytoskeletal functioning is needed to better understand Giardia's unique biology and pathogenesis.
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evidence for karyogamy and exchange of genetic material in the binucleate intestinal parasite Giardia intestinalis
Science, 2008Co-Authors: Marianne K Poxleitner, Meredith L Carpenter, Joel Mancuso, Chungju Rachel Wang, Scott C Dawson, Zacheus W CandeAbstract:The diplomonad parasite Giardia intestinalis contains two functionally equivalent nuclei that are inherited independently during mitosis. Although presumed to be asexual, Giardia has low levels of allelic heterozygosity, indicating that the two nuclear genomes may exchange genetic material. Fluorescence in situ hybridization performed with probes to an episomal plasmid suggests that plasmids are transferred between nuclei in the cyst, and transmission electron micrographs demonstrate fusion between cyst nuclei. Green fluorescent protein fusions of Giardial homologs of meiosis-specific genes localized to the nuclei of cysts, but not the vegetative trophozoite. These data suggest that the fusion of nuclei, or karyogamy, and subsequently somatic homologous recombination facilitated by the meiosis gene homologs, occur in the Giardial cyst.
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kinesin 13 regulates flagellar interphase and mitotic microtubule dynamics in Giardia intestinalis
Eukaryotic Cell, 2007Co-Authors: Joel Mancuso, Scott C Dawson, Susan A. House, M S Sagolla, David J Woessner, Lillian K Fritzlaylin, Zacheus W CandeAbstract: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.
