Occurrence of hepatic amoebiasis in rats inoculated intracaecally with a virulent strain of Entamoeba histolytica

In this paper, we attempted to define the role of phagocytosis in the virulence of Entamoeba histolytica. We have isolated, from a highly phagocytic and virulent strain, a clone deficient in phagocytosis. Trophozoites of wild-type strain HM1:IMSS were fed with Escherichia coli strain CR34-Thy- grown on 5-bromo,2'-deoxyuridine. The trophozoites that had incorporated the base analog through phagocytosis of the bacteria were killed by irradiation with 310 nm light. The survivors, presumably trophozoites defective in phagocytosis, were grown until log phase and submitted two more times to the selection procedure. Clone L-6, isolated from a subpopulation resulting from this selection procedure, showed 75-85% less erythrophagocytic activity than the wild-type strain. The virulence of clone L-6 and strain HM1:IMSS was measured. The inoculum required to induce liver abscesses in 50% of the newborn hamsters inoculated (AD50) of HM1:IMSS was 1.5 X 10(4) trophozoites. Clone L-6 trophozoites failed to induce liver abscesses in newborn hamsters even with inocula of 5 X 10(5) trophozoites. Virulence revertants were obtained by successive passage of L-6 trophozoites through the liver of young hamsters. The trophozoites that recovered the ability to produce liver abscesses simultaneously recuperate high erythrophagocytic rates. These results show that phagocytosis is involved in the aggressive mechanisms of E. histolytica.

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Virulent and avirulent Entamoeba histolytica and E. dispar differ in their cell surface phosphorylated glycolipids

Parasitology ◽

10.1017/s0031182096008396 ◽

1997 ◽

Vol 114 (2) ◽

pp. 95-104 ◽

Cited By ~ 31

Author(s):

S. MOODY ◽

S. BECKER ◽

Y. NUCHAMOWITZ ◽

D. MIRELMAN

Keyword(s):

Entamoeba Histolytica ◽

Polyclonal Antibodies ◽

Virulent Strain ◽

Flow Cytometric Analysis ◽

Structural Features ◽

Surface Distribution ◽

Flow Cytometric ◽

Virulent Strains ◽

Low Levels ◽

Modified Forms

Virulent strains of Entamoeba histolytica have been reported to produce a mixture of phosphoglycoconjugates that share some structural features with the lipophosphoglycans (LPGs) of Leishmania. Purification of these glycoconjugates is essential to their precise structural characterization. In this study we have extracted ‘LPG-like’ molecules from various virulent E. histolytica strains and purified on the basis of charge differences, 2 apparently related glycoconjugates a ‘LPG’ and a ‘lipophosphopeptidoglycan (LPPG)’. In marked contrast to the abundance of these ‘LPG’ and ‘LPPG’ molecules in the virulent strains, avirulent E. histolytica and E. dispar strains produce either very low, or no detectable levels of LPG, and either low levels or modified forms of ‘LPPG’. Monospecific polyclonal antibodies prepared against that ‘LPG’ of the virulent strain HM-1: IMSS cl6 identified epitopes shared between both the ‘LPG’ and the ‘LPPG’ of this and other virulent strains, using Western blot analysis. Flow cytometric analysis of a range of strains using these antibodies identified a surface distribution of these molecules and confirmed a correlation between surface exposure of epitopes bound by these antibodies and parasite virulence.

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Alkaline and acid phosphatase in the intestines of rats infected with a virulent strain of Entamoeba histolytica and treated with emetine and flagyl

Experimental Parasitology ◽

10.1016/0014-4894(73)90016-7 ◽

1973 ◽

Vol 33 (1) ◽

pp. 114-119 ◽

Cited By ~ 2

Author(s):

V.C Pandey ◽

G.P Dutta ◽

V.K.Mohan Rao

Keyword(s):

Acid Phosphatase ◽

Entamoeba Histolytica ◽

Virulent Strain ◽

Alkaline And Acid Phosphatase

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Entamoeba histolytica: Gene Expression Analysis of Cells Invading Tissues

The Scientific World JOURNAL ◽

10.1155/2014/364264 ◽

2014 ◽

Vol 2014 ◽

pp. 1-5 ◽

Cited By ~ 1

Author(s):

Helen C. Fernandes ◽

Ana F. Costa ◽

Michelle A. R. Freitas ◽

Almir S. Martins ◽

Jorge L. Pesquero ◽

...

Keyword(s):

Differential Expression ◽

Entamoeba Histolytica ◽

Virulent Strain ◽

Protozoan Parasite ◽

Specific Gene ◽

Future Studies ◽

Tissue Invasion ◽

Expression Of Genes ◽

Gene Transcripts ◽

Differential Expression Of Genes

Entamoeba histolyticais a protozoan parasite that presents a risk to the health of millions of people worldwide. Due to the existence of different clinical forms caused by the parasite and also different virulence levels presented by one strain, one would expect differences in the profile of gene transcripts between virulent and nonvirulent cultures. In this study we used the differential display to select gene segments related to invasiveness of amoeba. One Brazilian strain ofE. histolyticain two conditions, able or not to cause lesions in experimental animals, was used. RNA from this strain, was used to study the differential expression of genes. 29 specific gene fragments differentially expressed in the virulent strain were selected. By real-time PCR, six of these genes had confirmed their differential expression in the virulent culture. These genes may have important roles in triggering invasive amoebiasis and may be related to adaptation of trophozoites to difficulties encountered during colonization of the intestinal epithelium and liver tissue. Future studies with these genes may elucidate its actual role in tissue invasion byE. histolyticagenerating new pathways for diagnosis and treatment of amoebiasis.

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Erythrophagocytosis by Entamoeba histolytica.- Ultrastructural Study

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100094036 ◽

1972 ◽

Vol 30 ◽

pp. 156-157 ◽

Cited By ~ 1

Author(s):

Norberto Treviño ◽

Alfredo Feria-Velasco ◽

I. Ruiz de Chávez

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Entamoeba Histolytica ◽

Ultrastructural Study ◽

Saline Solution ◽

Physiological Saline ◽

Ultrastructural Level ◽

Hot Plate ◽

Physiological Saline Solution ◽

Axenic Conditions

Although erythrophagocytosis by various species of Entamoeba is a well known phenomenon this has not yet been studied in detail at the ultrastructural level. The present work deals with the description of the incorporation process of erythrocytes by trophozoites of E. histolytica. For this study, trophozoites of E. histolytica, HK-9:NIH strain cultured in axenic conditions and washed human erythrocytes were placed on a hot plate at 37°C in physiological saline solution. After 5 minutes, 2.5% glutarldehyde was added and the samples were processed according to conventional techniques for electron microscopy.Based upon light microscopy studies on living trophozoites in contact with erythrocytes, it seems that erythrophagocytosis only takes place in one pole of the parasite.

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Scanning electron microscopy of erythrophagocytosis by Entamoeba histolytica trophozoites

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012480x ◽

1992 ◽

Vol 50 (1) ◽

pp. 880-881

Author(s):

Victor Tsutsumi ◽

Adolfo Martinez-Palomo ◽

Kyuichi Tanikawa

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Red Blood Cells ◽

Entamoeba Histolytica ◽

Causative Agent ◽

Blood Cells ◽

Protozoan Parasite ◽

Complex Phenomenon ◽

Great Capacity ◽

Scanning Electron

The protozoan parasite Entamoeba histolytica is the causative agent of amebiasis in man. The trophozoite or motile form is a highly dynamic and pleomorphic cell with a great capacity to destroy tissues. Moreover, the parasite has the singular ability to phagocytize a variety of different live or death cells. Phagocytosis of red blood cells by E. histolytica trophozoites is a complex phenomenon related with amebic pathogenicity and nutrition.

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