The Experts below are selected from a list of 27435 Experts worldwide ranked by ideXlab platform
Aïda Bouratbine - One of the best experts on this subject based on the ideXlab platform.
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Development and evaluation of molecular tools for detecting and differentiating intestinal amoebae in healthy individuals
Parasitology, 2019Co-Authors: Amal Chihi, Karim Aoun, Christen Stensvold, Imène Ben-abda, Rania Ben-romdhane, Emna Siala, Aïda BouratbineAbstract:Amoebae are single-celled parasites frequently colonizing human gut. However, few molecular tools are available for accurate identification. Here, we evaluated a panel of polymerase chain reactions (PCRs) targeting Entamoeba histolytica, Entamoeba dispar, Entamoeba coli, Entamoeba hartmanni, Entamoeba polecki, Endolimax nana and Iodamoeba bütschlii. Thirty-six faecal samples (18 containing at least one amoeba species by microscopy and 18 microscopy negative for amoebae) were tested. Real-time PCRs were used for detection and differentiation of E. histolytica and E. dispar. Conventional PCR with Sanger sequencing were applied for detection and differentiation of E. coli, E. hartmanni, E. polecki, E. nana and I. bütschlii. All microscopy results were confirmed by DNA-based methods. However, more samples were positive for single and mixed amoebic species by DNA-based assays than by microscopy (22 vs 18 and 7 vs 1, respectively). DNA sequencing allowed identification of E. coli subtypes (ST1 and ST2), showed low intra-specific variation within E. hartmanni, identified two phylogenetically distinct groups within E. nana, and identified Iodamoeba at the ribosomal lineage level. Taking into account the high intra-genetic diversity within some of the species at the small subunit (SSU) rRNA gene level, amplification of SSU rRNA genes with subsequent sequencing represents a useful method for detecting, differentiating and subtyping intestinal amoebae.
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Short Report: First Molecular Identification of Entamoeba moshkovskii in Human Stool Samples in Tunisia
American Journal of Tropical Medicine and Hygiene, 2008Co-Authors: Soumaya Ben Ayed, Karim Aoun, Nadia Maamouri, Rvm Ben Abdallah, Aïda BouratbineAbstract:We report the first intestinal infections in Tunisia with Entamoeba moshkovskii in two healthy adults. Entamoeba moshkovskii cysts were distinguished from those of the morphologically identical parasites Entamoeba histolytica and Entamoeba dispar by specific nested polymerase chain reaction and sequencing.
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First molecular identification of Entamoeba moshkovskii in human stool samples in Tunisia.
American Journal of Tropical Medicine and Hygiene, 2008Co-Authors: Soumaya Ben Ayed, Karim Aoun, Nadia Maamouri, Rym Ben Abdallah, Aïda BouratbineAbstract:We report the first intestinal infections in Tunisia with Entamoeba moshkovskii in two healthy adults. Entamoeba moshkovskii cysts were distinguished from those of the morphologically identical parasites Entamoeba histolytica and Entamoeba dispar by specific nested polymerase chain reaction and sequencing.
Egbert Tannich - One of the best experts on this subject based on the ideXlab platform.
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Entamoeba ranarum Infection in a Ball Python (Python regius)
Journal of Comparative Pathology, 2020Co-Authors: L.m. Michaely, Egbert Tannich, K. Von Dörnberg, V Molnár, Dennis Tappe, Marion Hewicker-trautwein, Peter WohlseinAbstract:Summary The pathogenic Entamoeba species in snakes is widely regarded to be Entamoeba invadens, which can cause severe amoebiasis with up to 100% mortality. In this case report, we describe a ball python (Python regius) that died after short-term weight loss. Necropsy revealed severe necrotizing colitis with large numbers of intralesional Entamoeba trophozoites. Molecular genetic analysis identified these trophozoites as Entamoeba ranarum, a parasite more usually found in amphibians. Furthermore, the extended history revealed that toads (Rhinella marina) had been housed together with the python. This report illustrates the danger of protozoal cross-infections in exotic animals as well as the importance of molecular genetic tools in Entamoeba diagnosis.
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Genomic diversity of the human intestinal parasite Entamoeba histolytica
Genome Biology, 2012Co-Authors: Gareth D Weedall, Pia Koldkjær, Iris Bruchhaus, C. Graham Clark, Egbert Tannich, Steve Paterson, Neil HallAbstract:Background Entamoeba histolytica is a significant cause of disease worldwide. However, little is known about the genetic diversity of the parasite. We re-sequenced the genomes of ten laboratory cultured lines of the eukaryotic pathogen Entamoeba histolytica in order to develop a picture of genetic diversity across the genome.
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A novel Entamoeba histolytica inositol phosphate kinase catalyzes the formation of 5PP-Ins(1,2,3,4,6)P5
Molecular and Biochemical Parasitology, 2011Co-Authors: Benjamin Loser, Marcus M. Nalaskowski, Werner Fanick, Egbert Tannich, Georg W. MayrAbstract:Abstract The parasitic protozoan Entamoeba histolytica is able to invade human tissues by secreting proteolytic enzymes. This secretion is regulated by inositol phosphate-mediated Ca2+ release from internal stores. To further investigate the inositol phosphate metabolism of Entamoeba histolytica four putative inositol phosphate kinase genes (ehipk1-4) were identified and their expression analyzed by real-time quantitative PCR using RNA of trophozoites. Furthermore inositol phosphate kinase EhIPK1 was recombinantly expressed, purified and enzymatically characterized. Its main activity is the conversion of InsP6 to 5PP-Ins(1,2,3,4,6)P5, one of the main inositol phosphates found in Entamoeba histolytica. Remarkably, EhIPK1 possesses several additional enzymatic activities, e.g. the phosphorylation of the Ca2+-releasing second messenger Ins(1,4,5)P3.We were able to identify several compounds with inhibitory potential against EhIPK1. Because of the important role of inositol phosphates in the invasion of human tissues by Entamoeba histolytica, inositol phosphate metabolizing enzymes are interesting targets for novel therapeutic approaches.
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increased sampling reveals novel lineages of Entamoeba consequences of genetic diversity and host specificity for taxonomy and molecular detection
Protist, 2011Co-Authors: Rune C Stensvold, Egbert Tannich, Marianne Lebbad, Emma L Victory, Jaco J Verweij, Mohammed A Alfellani, Paulette Legarraga, Graham C ClarkAbstract:To expand the representation for phylogenetic analysis, ten additional complete Entamoeba small-subunit rRNA gene sequences were obtained from humans, non-human primates, cattle and a tortoise. For some novel sequences no corresponding morphological data were available, and we suggest that these organisms should be referred to as ribosomal lineages (RL) rather than being assigned species names at present. To investigate genetic diversity and host specificity of selected Entamoeba species, a total of 91 new partial small subunit rRNA gene sequences were obtained, including 49 from Entamoeba coli, 18 from Entamoeba polecki, and 17 from Entamoeba hartmanni. We propose a new nomenclature for significant variants within established Entamoeba species. Based on current data we propose that the uninucleated-cyst-producing Entamoeba infecting humans is called Entamoeba polecki and divided into four subtypes (ST1-ST4) and that Entamoeba coli is divided into two subtypes (ST1-ST2). New hosts for several species were detected and, while host specificity and genetic diversity of several species remain to be clarified, it is clear that previous reliance on cultivated material has given us a misleading and incomplete picture of variation within the genus Entamoeba.
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Zur Labordiagnostik von Entamoeba histolytica-Infektionen The laboratory diagnosis of Entamoeba histolytica-infections
Labmedicine, 2004Co-Authors: Egbert TannichAbstract:Classical stool microscopy for the identification of intestinal protozoan infections is more and more substituted by new detection assays such as immunofluorescence, antigen-ELISA or PCR. This is particularly important for the diagnosis of Entamoeba histolytica, as this parasite is microscopically indistinguishable from non-pathogenic amoeba species such as Entamoeba dispar or Entamoeba moshkovskii.
Graham C Clark - One of the best experts on this subject based on the ideXlab platform.
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increased sampling reveals novel lineages of Entamoeba consequences of genetic diversity and host specificity for taxonomy and molecular detection
Protist, 2011Co-Authors: Rune C Stensvold, Egbert Tannich, Marianne Lebbad, Emma L Victory, Jaco J Verweij, Mohammed A Alfellani, Paulette Legarraga, Graham C ClarkAbstract:To expand the representation for phylogenetic analysis, ten additional complete Entamoeba small-subunit rRNA gene sequences were obtained from humans, non-human primates, cattle and a tortoise. For some novel sequences no corresponding morphological data were available, and we suggest that these organisms should be referred to as ribosomal lineages (RL) rather than being assigned species names at present. To investigate genetic diversity and host specificity of selected Entamoeba species, a total of 91 new partial small subunit rRNA gene sequences were obtained, including 49 from Entamoeba coli, 18 from Entamoeba polecki, and 17 from Entamoeba hartmanni. We propose a new nomenclature for significant variants within established Entamoeba species. Based on current data we propose that the uninucleated-cyst-producing Entamoeba infecting humans is called Entamoeba polecki and divided into four subtypes (ST1-ST4) and that Entamoeba coli is divided into two subtypes (ST1-ST2). New hosts for several species were detected and, while host specificity and genetic diversity of several species remain to be clarified, it is clear that previous reliance on cultivated material has given us a misleading and incomplete picture of variation within the genus Entamoeba.
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new insights into the phylogeny of Entamoeba species provided by analysis of four new small subunit rrna genes
International Journal of Systematic and Evolutionary Microbiology, 2006Co-Authors: Graham C Clark, Joerg Blessmann, Farrokh Kaffashian, Blessing Tawari, J J Windsor, Anke Twiggflesner, Mina Clare Gwynne Daviesmorel, Frank Ebert, Babett Peschel, An Le VanAbstract:Sequences of small-subunit rRNA genes have been obtained for four new isolates of Entamoeba. Phylogenetic analyses give new insights into the evolution of these organisms. A novel Entamoeba from pigs in Vietnam that produces uninucleate cysts proved to be unrelated to other uninucleated cyst-producing species. Revival of the name Entamoeba suis for this organism is proposed. Instead of being related to Entamoeba polecki, it shares a recent common ancestor with the non-encysting Entamoeba gingivalis in a lineage that is basal to the tetranucleate cyst-producing clade. This suggests that species producing cysts with four nuclei are descended from an ancestor that produced cysts with a single nucleus. An Entamoeba from a horse was isolated in culture. No cysts were observed in the original stool sample but the sequence is placed unequivocally within the clade of tetranucleate cyst-producing species with no other sequences being specifically related. Revival of the name Entamoeba equi for this organism is proposed. The Entamoeba ecuadoriensis sequence was found to be the most closely related to Entamoeba histolytica and Entamoeba dispar, as predicted, despite the organism having been an environmental isolate originally assigned to Entamoeba moshkovskii. Finally, a partial E. polecki gene sequence from a pig proved to be virtually identical to that of Entamoeba struthionis from an ostrich, suggesting that the latter name is a synonym.
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intraspecific variation and phylogenetic relationships in the genus Entamoeba as revealed by riboprinting
Journal of Eukaryotic Microbiology, 1997Co-Authors: Graham C Clark, Louis S DiamondAbstract:. Eighty-seven isolates of amebae assigned to the genus Entamoeba have been studied by riboprinting (restriction enzyme polymorphism analysis of polymerase chain reaction amplified small subunit ribosomal RNA genes). Twenty-four distinct patterns were obtained, most of which corresponded to previously described species. In three species (Entamoeba coli, Entamoeba gingivalis and Entamoeba moshkovskii) intraspecific variation was detected that led to the grouping of isolates into ‘ribodemes’ (populations of amebae that share the same riboprint pattern). The riboprint data were used to estimate genetic distances among and within species for the construction of phylogenetic trees based on parsimony and distance analyses. The trees obtained with the two methods are largely congruent. In some cases the estimated distances between species were greater than the upper limit recommended for the fragment comigration method of analysis indicating unusually deep branches within this genus. However, it appears that those species producing cysts with eight nuclei, those producing cysts with one nucleus, and those producing cysts with four nuclei form morphologically based groups that are supported by the riboprint data. The oral parasite Entamoeba gingivalis, which does not encyst, clusters with the third group indicating secondary loss of this ability.
J Harkness - One of the best experts on this subject based on the ideXlab platform.
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laboratory diagnostic techniques for Entamoeba species
Clinical Microbiology Reviews, 2007Co-Authors: R Fotedar, Damien Stark, Nigel W Beebe, Deborah Marriott, John Ellis, J HarknessAbstract:The genus Entamoeba contains many species, six of which (Entamoeba histolytica, Entamoeba dispar, Entamoeba moshkovskii, Entamoeba polecki, Entamoeba coli, and Entamoeba hartmanni) reside in the human intestinal lumen. Entamoeba histolytica is the causative agent of amebiasis and is considered a leading parasitic cause of death worldwide in humans. Although recent studies highlight the recovery of E. dispar and E. moshkovskii from patients with gastrointestinal symptoms, there is still no convincing evidence of a causal link between the presence of these two species and the symptoms of the host. New approaches to the identification of E. histolytica are based on detection of E. histolytica-specific antigen and DNA in stool and other clinical samples. Several molecular diagnostic tests, including conventional and real-time PCR, have been developed for the detection and differentiation of E. histolytica, E. dispar, and E. moshkovskii in clinical samples. The purpose of this review is to discuss different methods that exist for the identification of E. histolytica, E. dispar, and E. moshkovskii which are available to the clinical diagnostic laboratory. To address the need for a specific diagnostic test for amebiasis, a substantial amount of work has been carried out over the last decade in different parts of the world. The molecular diagnostic tests are increasingly being used for both clinical and research purposes. In order to minimize undue treatment of individuals infected with other species of Entamoeba such as E. dispar and E. moshkovskii, efforts have been made for specific diagnosis of E. histolytica infection and not to treat based simply on the microscopic examination of Entamoeba species in the stool. The incorporation of many new technologies into the diagnostic laboratory will lead to a better understanding of the public health problem and measures to control the disease.
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pcr detection of Entamoeba histolytica Entamoeba dispar and Entamoeba moshkovskii in stool samples from sydney australia
Journal of Clinical Microbiology, 2007Co-Authors: R Fotedar, Damien Stark, Nigel W Beebe, Deborah Marriott, John Ellis, J HarknessAbstract:This study investigated the presence of Entamoeba histolytica, Entamoeba dispar, and Entamoeba moshkovskii in stool samples from a patient population in Sydney, Australia. Stool samples were tested by microscopy and PCR. Five patients were found with E. histolytica infections, while E. dispar and E. moshkovskii were observed in 63 (70.8%) and 55 (61.8%) patients, respectively, by PCR. This is the first study in Australia using molecular techniques to determine the presence of E. histolytica, E. dispar, and E. moshkovskii.
Joerg Blessmann - One of the best experts on this subject based on the ideXlab platform.
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new insights into the phylogeny of Entamoeba species provided by analysis of four new small subunit rrna genes
International Journal of Systematic and Evolutionary Microbiology, 2006Co-Authors: Graham C Clark, Joerg Blessmann, Farrokh Kaffashian, Blessing Tawari, J J Windsor, Anke Twiggflesner, Mina Clare Gwynne Daviesmorel, Frank Ebert, Babett Peschel, An Le VanAbstract:Sequences of small-subunit rRNA genes have been obtained for four new isolates of Entamoeba. Phylogenetic analyses give new insights into the evolution of these organisms. A novel Entamoeba from pigs in Vietnam that produces uninucleate cysts proved to be unrelated to other uninucleated cyst-producing species. Revival of the name Entamoeba suis for this organism is proposed. Instead of being related to Entamoeba polecki, it shares a recent common ancestor with the non-encysting Entamoeba gingivalis in a lineage that is basal to the tetranucleate cyst-producing clade. This suggests that species producing cysts with four nuclei are descended from an ancestor that produced cysts with a single nucleus. An Entamoeba from a horse was isolated in culture. No cysts were observed in the original stool sample but the sequence is placed unequivocally within the clade of tetranucleate cyst-producing species with no other sequences being specifically related. Revival of the name Entamoeba equi for this organism is proposed. The Entamoeba ecuadoriensis sequence was found to be the most closely related to Entamoeba histolytica and Entamoeba dispar, as predicted, despite the organism having been an environmental isolate originally assigned to Entamoeba moshkovskii. Finally, a partial E. polecki gene sequence from a pig proved to be virtually identical to that of Entamoeba struthionis from an ostrich, suggesting that the latter name is a synonym.
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real time pcr for detection and differentiation of Entamoeba histolytica and Entamoeba dispar in fecal samples
Journal of Clinical Microbiology, 2002Co-Authors: Joerg Blessmann, Jonathan I Ravdin, Heidrun Buss, Phuong Anh Ton Nu, Binh T Dinh, Mohamed Abd D Alla, Terry F H G Jackson, Egbert TannichAbstract:A closed-tube, real-time PCR assay was developed for sensitive and specific detection and differentiation of the two closely related intestinal protozoan parasites Entamoeba histolytica and Entamoeba dispar directly from human feces. The assay is performed with the LightCycler system using fluorescence-labeled detection probes and primers amplifying a 310-bp fragment from the high-copy-number, ribosomal DNA-containing ameba episome. The assay was able to detect as little as 0.1 parasite per g of feces. The two pairs of primers used were specific for the respective ameba species, and results were not influenced by the presence of other Entamoeba species even when present in exceeding amounts. PCR was evaluated using several hundred stool samples from areas of amebiasis endemicity in Vietnam and South Africa, and results were compared with those of microscopy and ameba culture. PCR was found to be significantly more sensitive than microscopy or culture, as all samples positive by microscopy and 22 out of 25 (88%) samples positive by culture were also positive by PCR, but PCR revealed a considerable number of additional E. histolytica- or E. dispar-positive samples. Compared to culture and subsequent ameba differentiation by isoenzyme analysis, PCR was 100% specific for each of the two Entamoeba species. Interestingly, the comparison with PCR revealed that culture, in particular, underestimates E. histolytica infections. Given the high sensitivity and specificity of the developed PCR assay, the inability of microscopy to distinguish between the two ameba species, and the time it takes to culture and subsequently differentiate Entamoebae by isoenzyme analysis, this assay is more suitable than microscopy or culture to correctly diagnose intestinal E. histolytica or E. dispar infection.
