関: Amebiasis

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/06/18 21:22:53」(JST)

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Entamoeba is a genus of Amoebozoa found as internal parasites or commensals of animals.

In 1875, Fedor Lösch described the first proven case of amoebic dysentery in St Petersburg, Russia. He referred to the amoeba he observed microscopically as 'Amoeba coli'; however it is not clear whether he was using this as a descriptive term or intended it as a formal taxonomic name.^[1] The genus Entamoeba was defined by Casagrandi and Barbagallo for the species Entamoeba coli, which is known to be a commensal organism.^[2] Lösch's organism was renamed Entamoeba histolytica by Fritz Schaudinn in 1903; he later died, in 1906, from a self-inflicted infection when studying this amoeba. For a time during the first half of the 20th century the entire genus Entamoeba was transferred to Endamoeba, a genus of amoebas infecting invertebrates about which little is known. This move was reversed by the International Commission on Zoological Nomenclature in the late 1950s, and Entamoeba has stayed 'stable' ever since.

Species

Several species are found in humans. Entamoeba histolytica is the pathogen responsible for 'amoebiasis' (which includes amoebic dysentery and amoebic liver abscesses). Adult Entamoeba is called trophozoite and is monopodial. It has two forms, magna or pathogenic form and minuta, non-pathogenic form found in the intestine. This species of Entamoeba has no contractile vacuole. Others such as Entamoeba coli (not to be confused with Escherichia coli) and Entamoeba dispar ^[3] are harmless. With the exception of Entamoeba gingivalis, which lives in the mouth, and E. moshkovskii, which is frequently isolated from river and lake sediments, all Entamoeba species are found in the intestines of the animals they infect. Entamoeba invadens is a species that can cause a disease similar to E. histolytica but in reptiles. In contrast to other species, E. invadens forms cysts in vitro in the absence of bacteria and is used as a model system to study this aspect of the life cycle. Many other species of Entamoeba have been described and it is likely that many others remain to be found.

Structure

Entamoeba gingivalis

Entamoeba cells are small, with a single nucleus and typically a single lobose pseudopod taking the form of a clear anterior bulge. They have a simple life cycle. The trophozoite (feeding-dividing form) is approximately 10-20 μm in diameter and feeds primarily on bacteria. It divides by simple binary fission to form two smaller daughter cells. Almost all species form cysts, the stage involved in transmission (the exception is Entamoeba gingivalis). Depending on the species, these can have one, four or eight nuclei and are variable in size; these characteristics help in species identification.

Classification

Entamoeba belongs to the Archamoebae, which like many other anaerobic eukaryotes lack mitochondria. This group also includes Endolimax and Iodamoeba, which also live in animal intestines and are similar in appearance to Entamoeba, although this may partly be due to convergence. Also in this group are the free-living amoebo-flagellates of the genus Mastigamoeba and related genera.^[4] Certain other genera of symbiotic amoebae, such as Endamoeba, might prove to be synonyms of Entamoeba but this is still unclear.

Culture

Fission

Studying Entamoeba invadens, David Biron of the Weizmann Institute of Science and coworkers found that about one third of the cells are unable to separate unaided and recruit a neighboring amoeba (dubbed the "midwife") to complete the fission.^[5] He writes:

When an amoeba divides, the two daughter cells stay attached by a tubular tether which remains intact unless mechanically severed. If called upon, the neighbouring amoeba midwife travels up to 200 μm towards the dividing amoeba, usually advancing in a straight trajectory with an average velocity of about 0.5 μm/s. The midwife then proceeds to rupture the connection, after which all three amoebae move on.

They also reported a similar behavior in Dictyostelium.^[6]

Since E.histolytica does not form cysts in the absence of bacteria, E.invadens has become used as a model for encystation studies as it will form cysts under axenic growth conditions, which simplifies analysis. After inducing encystation in E.invadens, DNA replication increases initially and then slows down. On completion of encystation, predominantly tetra-nucleate cysts are formed along with some uni-, bi- and tri-nucleate cysts.^[7]

Differentiation and cell biology

Uni-nucleated trophozoites convert into cysts in a process called encystation. The number of nuclei in the cyst varies from 1 to 8 among species and is one of the characteristics used to tell species apart. Of the species already mentioned, Entamoeba coli forms cysts with 8 nuclei while the others form tetra-nucleated cysts. Since E. histolytica does not form cysts in vitro in the absence of bacteria, it is not possible to study the differentiation process in detail in that species. Instead the differentiation process is studied using E. invadens, a reptilian parasite that causes a very simiilar disease to E. histolytica and which can be induced to encyst in vitro. Until recently there was no genetic transfection vector available for this organism and detailed study at the cellular level was not possible. However, recently a transfection vector was developed and the transfection conditions for E. invadens were optimised which should enhance the research possibilities at the molecular level of the differentiation process.^[8]^[9]

References

^ Lösch, F. (1875) Massenhafte Entwickelung von Amöben im Dickdarm. Virchow's Archiv 65: 196-211.
^ Casagrandi O & Barbagallo P (1895) Ricerche biologiche e cliniche suli' Amoeba coli (Lösch). (Nota preliminare). Bull. Accad. Gioenia Sci. Nat. Catania 39: 4.
^ Diamond LS and Clark CG (1993). "A redescription of Entamoeba histolytica Schaudinn, 1903 (emended Walker, 1911) separating it from Entamoeba dispar Brumpt, 1925". Journal of Eukaryotic Microbiology 40 (3): 1340–344. PMID 8508172.
^ Stensvold CR, Lebbad M, and Clark CG (January 2012). "Last of the human protists: the phylogeny and genetic diversity of Iodamoeba.". Molecular Biology and Evolution. (in press) (1): 39–42. doi:10.1093/molbev/msr238. PMID 21940643.
^ Biron D, Libros P, Sagi D, Mirelman D, Moses E (2001). "Asexual reproduction: 'Midwives' assist dividing amoebae". Nature 410 (6827): 430. doi:10.1038/35068628. PMID 11260701.
^ Nagasaki, A and Uyeda, T., Q., P.; Chemotaxis-Mediated Scission Contributes to Efficient Cytokinesis in Dictyostelium, Cell Motility and the Cytoskeleton; Vol. 65; Issue 11; Article first published online: 7 AUG 2008
^ Singh N, Bhattacharya S, Paul J (2010). "Entamoeba invadens: Dynamics of DNA synthesis during differentiation from trophozoite to cyst". Experimental Parasitology 127 (2): 329–33. doi:10.1016/j.exppara.2010.08.013. PMID 20727884.
^ Singh, Nishant; Ojha, Sandeep; Bhattacharya, Alok; Bhattacharya, Sudha (2012). "Establishment of a transient transfection system and expression of firefly luciferase in Entamoeba invadens". Molecular and Biochemical Parasitology 183 (1): 90– 93. doi:10.1016/j.molbiopara.2012.01.003.
^ Singh, Nishant; Ojha, Sandeep; Bhattacharya, Alok; Bhattacharya, Sudha (2012). "Stable transfection and continuous expression of heterologous genes in Entamoeba invadens". Molecular and Biochemical Parasitology 184 (1): 9–12. doi:10.1016/j.molbiopara.2012.02.012.

External links

Entamoeba Homepage
Pathema-Entamoeba Resource
Entamoeba Genome Database at AmoebaDB

UpToDate Contents

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1. 赤痢アメーバによる腸菅アメーバ症 intestinal entamoeba histolytica amebiasis
2. 赤痢アメーバによる腸菅外アメーバ症 extraintestinal entamoeba histolytica amebiasis
3. 非病原性腸内原虫 nonpathogenic enteric protozoa
4. 旅行者下痢症：臨床症状、診断、および治療 travelers diarrhea clinical manifestations diagnosis and treatment
5. 資源に富んだ国における急性下痢の疫学および原因 epidemiology and causes of acute diarrhea in resource rich countries

English Journal

First report of mixed Entamoeba polecki (ST 1) and E. suis infection in piglets shedding abnormalfeces by histopathological and molecular surveys.

Matsubayashi M, Sasagawa Y, Aita T, Tokoro M, Haritani M, Shibahara T.
Acta parasitologica.Acta Parasitol.2016 Dec 1;61(4):665-670. doi: 10.1515/ap-2016-0093.
Of the three species of Entamoeba found in swine, namely E. histolytica, E. polecki and E. suis, E. histolytica can also infect humans, producing colitis or abscesses of liver and leading to death. However, the pathogenicity of other species of Entamoeba has not been fully characterized. Here, we co
PMID 27787199

Entamoeba histolytica: Overexpression of the gal/galnac lectin, ehcp2 and ehcp5 genes in an in vivo model of amebiasis.

Sánchez V1, Serrano-Luna J2, Ramírez-Moreno E3, Tsutsumi V4, Shibayama M5.
Parasitology international.Parasitol Int.2016 Dec;65(6 Pt A):665-667. doi: 10.1016/j.parint.2016.08.009. Epub 2016 Sep 5.
The parasite Entamoeba histolytica causes intestinal amebiasis and amebic liver abscess as its main extraintestinal manifestation. To study the in vivo events related to inflammation and the interactions between hosts and parasites during amebiasis, we designed a novel model of host-parasite interac
PMID 27616150

Performance of microscopy and ELISA for diagnosing Giardia duodenalis infection in different pediatric groups.

Silva RK1, Pacheco FT1, Martins AS1, Menezes JF1, Costa-Ribeiro H Jr2, Ribeiro TC2, Mattos ÂP2, Oliveira RR3, Soares NM1, Teixeira MC4.
Parasitology international.Parasitol Int.2016 Dec;65(6 Pt A):635-640. doi: 10.1016/j.parint.2016.08.012. Epub 2016 Aug 30.
Techniques for Giardia diagnosis based on microscopy are usually applied as routine laboratory testing; however, they typically exhibit low sensitivity. This study aimed to evaluate Giardia duodenalis and other intestinal parasitic infections in different pediatric groups, with an emphasis on the co
PMID 27586394

Japanese Journal

Structural and mutational analysis of amino acid residues involved in ATP specificity of Escherichia coli acetate kinase

Yoshioka Aya,Murata Kousaku,Kawai Shigeyuki
Journal of bioscience and bioengineering 118(5), 502-507, 2014-11
NAID 40020275313

アメーバ赤痢

小林泰一郎,渡辺恒二
消化器内科 59(3), 281-290, 2014-09
NAID 40020212795

Serological Surveillance Development for Tropical Infectious Diseases Using Simultaneous Microsphere-Based Multiplex Assays and Finite Mixture Models

Fujii Yoshito,Kaneko Satoshi,Nzou Samson Muuo,Mwau Matilu,Njenga Sammy M.,Tanigawa Chihiro,Kimotho James,Mwangi Anne Wanjiru,Kiche Ibrahim,Matsumoto Sohkichi,Niki Mamiko,Osada-Oka Mayuko,Ichinose Yoshio,Inoue Manabu,Itoh Makoto,Tachibana Hiroshi,Ishii Kazunari,Tsuboi Takafumi,Yoshida Lay Myint,Mondal Dinesh,Haque Rashidul,Hamano Shinjiro,Changoma Mwatasa,Hoshi Tomonori,Kamo Ken-ichi,Karama Mohamed,Miura Masashi,Hirayama Kenji
PLoS Neglected Tropical Diseases 8(7), e3040, 2014-07-31
… To establish a simple and practical seroprevalence detection system, we developed a microsphere-based multiplex immunoassay system and evaluated utility using samples obtained in Kenya.Methods:We developed a microsphere-based immuno-assay system to simultaneously measure the individual levels of plasma antibody (IgG) against 8 antigens derived from 6 pathogens: Entamoeba histolytica (C-IgL), Leishmania donovani (KRP42), Toxoplasma gondii (SAG1), Wuchereria bancrofti (SXP1), HIV (gag, gp120 and gp41), and Vibrio cholerae (cholera toxin). …
NAID 120005477034

Related Pictures

★リンクテーブル★

リンク元	「メトロニダゾール」「エントアメーバ」「エントアメーバ属」
拡張検索	「Entamoeba histolytica」「Entamoeba属」「Entamoeba invadens」

「メトロニダゾール」

Entamoeba
	Entamoeba coli
Scientific classification
Domain:	Eukaryota
Phylum:	Amoebozoa
Class:	Archamoebae
Genus:	Entamoeba; Casagrandi & Barbagallo, 1897
Species
	E. bangladeshi; E. bovis; E. chattoni; E. coli; E. dispar; E. ecuadoriensis; E. equi; E. gingivalis; E. hartmanni; E. histolytica; E. insolita; E. invadens; E. moshkovskii; E. muris; E. nuttalli; E. polecki; E. ranarum; E. struthionis; E. suis; E. terrapinae

　　[★]

英: metronidazole, MTZ
商: フラジール Flagyl, Metro-IV、アスゾール。ランピオンパック(ランソプラゾール、アモキシシリン、メトロニダゾール)
関: トリコモナス

first aid step1 2006 p.139,142,148,165,172,178,208,276,282

特徴

原虫(トリコモナスなど)による感染症に対して用いる

構造

作用機序 PPC. 641, 647

メトロニダゾールの活性化には嫌気性生物の発酵に関与する酵素 pyruvate-derredocin oxidoreductase,PFORが必要
pyruvate-ferredoxin oxidoreductaseはferredoxinをreduced ferredoxinに変換するが、これに共役してメトロニダゾールがreduced metronidazole(活性型)に変換される。

PFORは宿主細胞(好気性生物)には存在しないので、原虫や嫌気性生物が特異的に障害を受ける

微生物の蛋白質、膜、DNAに傷害を与える

適応

USMLE (first aid step1 2006 p.172)

横隔膜より下の嫌気性菌に対して用いられる

原虫：Giardia, Entamoeba, Trichomonas
嫌気性菌：Bacteroides, Clostridium
細菌：Clostridium difficile, Helicobacter pylori, Gardnerella vaginalis

H. pylori：bismuth + amoxicillin/tetracycline + metronidazole

副作用

disulfiram-like reaction with alcohol; headache,metallic taste (first aid step1 2006 p.172)

「エントアメーバ」

　　[★]

ラ: Entamoeba
関: エントアメーバ属、Entamoeba属

「エントアメーバ属」

　　[★]

ラ: Entamoeba
関: エントアメーバ、Entamoeba属

「Entamoeba histolytica」

　　[★] 赤痢アメーバ

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「Entamoeba属」

　　[★]

ラ: Entamoeba
関: エントアメーバ属、エントアメーバ

「Entamoeba invadens」

　　[★]

赤痢アメーバ

関: E. histolytica、Entamoeba histolytica

[1] Lösch, F. (1875) Massenhafte Entwickelung von Amöben im Dickdarm. Virchow's Archiv 65: 196-211.

[2] Casagrandi O & Barbagallo P (1895) Ricerche biologiche e cliniche suli' Amoeba coli (Lösch). (Nota preliminare). Bull. Accad. Gioenia Sci. Nat. Catania 39: 4.

[3] Diamond LS and Clark CG (1993). "A redescription of Entamoeba histolytica Schaudinn, 1903 (emended Walker, 1911) separating it from Entamoeba dispar Brumpt, 1925". Journal of Eukaryotic Microbiology 40 (3): 1340–344. PMID 8508172.

[4] Stensvold CR, Lebbad M, and Clark CG (January 2012). "Last of the human protists: the phylogeny and genetic diversity of Iodamoeba.". Molecular Biology and Evolution. (in press) (1): 39–42. doi:10.1093/molbev/msr238. PMID 21940643.

[5] Biron D, Libros P, Sagi D, Mirelman D, Moses E (2001). "Asexual reproduction: 'Midwives' assist dividing amoebae". Nature 410 (6827): 430. doi:10.1038/35068628. PMID 11260701.

[6] Nagasaki, A and Uyeda, T., Q., P.; Chemotaxis-Mediated Scission Contributes to Efficient Cytokinesis in Dictyostelium, Cell Motility and the Cytoskeleton; Vol. 65; Issue 11; Article first published online: 7 AUG 2008

[7] Singh N, Bhattacharya S, Paul J (2010). "Entamoeba invadens: Dynamics of DNA synthesis during differentiation from trophozoite to cyst". Experimental Parasitology 127 (2): 329–33. doi:10.1016/j.exppara.2010.08.013. PMID 20727884.

[8] Singh, Nishant; Ojha, Sandeep; Bhattacharya, Alok; Bhattacharya, Sudha (2012). "Establishment of a transient transfection system and expression of firefly luciferase in Entamoeba invadens". Molecular and Biochemical Parasitology 183 (1): 90– 93. doi:10.1016/j.molbiopara.2012.01.003.

[9] Singh, Nishant; Ojha, Sandeep; Bhattacharya, Alok; Bhattacharya, Sudha (2012). "Stable transfection and continuous expression of heterologous genes in Entamoeba invadens". Molecular and Biochemical Parasitology 184 (1): 9–12. doi:10.1016/j.molbiopara.2012.02.012.

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案内

案内

Entamoeba