Cyst production and transmission of Entamoeba and Endolimax (original) (raw)
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Encystation of Entamoeba histolytica in Axenic Culture
Microorganisms, 2021
Entamoeba histolytica is a parasitic protozoan that causes amoebic dysentery, which affects approximately 90 million people each year worldwide. E. histolytica is transmitted through ingestion of food and water contaminated with the cyst form, which undergoes excystation in the small intestine to the trophozoite form that colonizes the large intestine. The reptile pathogen Entamoeba invadens has served as a model for studying stage conversion between the trophozoite and cyst form due to lack of reproducible encystation of E. histolytica in the laboratory. Although much has been learned about encystation and excystation using E. invadens, the findings do not fully translate to E. histolytica due to the extensive genetic and host differences between these species. Here, we present the first reproducible encystation of E. histolytica in vitro. The cysts produced were viable and displayed the four characteristic hallmarks: round shape, chitinous cell wall, tetranucleation, and detergent...
HLA characterization in adult asymptomatic cyst passers of Entamoeba histolytica/E. dispar
Parasitology Research, 1999
The present work aimed at studying the possible association of HLA antigens with Entamoeba histolytica/E. dispar asymptomatic infection in a Mexican mestizo population. A case-control design was selected for evaluation of the role of genetic markers in parasite infection. For this purpose the HLA-A, HLA-B, and HLA-DR profiles of a population of asymptomatic E. histolytica/E. dispar adult cyst passers (cases) and a corresponding nonparasitized adult group (controls) followed for 12 months were identified. Entamoeba species were identified through zymodeme patterns and/or amplification of species-specific DNA sequences. A healthy, nonparasitized group of individuals was included as a control. Our results show that apparently, no specific HLA marker is associated with the asymptomatic cyst passers' condition. These findings have to be added to previous results in which, in contrast to a demonstrated association between HLA-DR3 and amebic liver abscess in Mexican mestizo adults and infants, no significant association with amebic rectocolitis was found.
Entamoeba histolytica cysts with a defective wall formed under axenic conditions
Parasitology Research, 1993
Axenic HK9 Entamoeba h&totytica strain amoebae, maintained in PEHS medium, displayed several cystic characteristics that involve an active process of cystic wall formation, cellular volume and density diminution, and one or two nuclear divisions. The differentiation process was asynchronic, beginning after the logarithmic growth phase. The axenic cysts, which were maintained in a 50 mOsm/kg medium at 4 ~ C for 72 h, produced growing trophozoites within 1-7 days of incubation at 36 ~ C in fresh medium. Negative results were obtained with trophozoites submitted to the above treatment, and with axenic cysts maintained in double-distilled water at 4~ for 24 h, or in 0.1% sarkosyl, for 10 min at room temperature instead of 55 mosmol/kg
Parasitology International, 2000
Entamoeba histolyticarEntamoeba dispar was isolated from 50 asymptomatic amebic cyst passers in three institutions for the mentally retarded in Kanagawa Prefecture, Japan. To distinguish between E. histolytica and E. dispar, the isolates were analyzed by PCR, reactivity to monoclonal antibodies, and zymodemes. All isolates were identified as E. histolytica. The results lead us to conceive that, in Japan, E. histolytica is predominant even in asymptomatic cyst passers.
Genetic Variation among Human Isolates of Uninucleated Cyst-Producing Entamoeba Species
2001
Twelve human infections with Entamoeba spp. producing uninucleated cysts were studied. DNA was ex- tracted from infected feces and used to amplify part of the ameba small-subunit rRNA gene. Sequence analysis identified four distinct types of Entamoeba, all of which are related to Entamoeba polecki and E. chattoni and two of which have not been reported previously. Whether these genetic
Detection and differentiation of two morphologically identical species of Entamoeba
Background: Infection with Entamoeba histolytica is a worldwide public health problem. Diagnosis of this parasite by conventional microscopy is almost impossible, because it is morphologically indistinguishable from E. dispar, which is non pathogenic. Objective: To detect and differentiate E. histolytica from E. dispar by PCR technique and to determine the prevalence of trophozoites and cysts of E. histolytica /E. dispar by microscopy of fresh stool specimen among out patients of Jimma University Hospital to provide baseline data for further study. Method: A cross-sectional study was conducted from Feb. 24 -Mar. 23, 2003 in Jimma University Hospital among patients with clinical signs and symptoms of intestinal complaints. The stool samples were examined microscopically and by PCR and Solution Hybridization Enzyme Linked Immuno assay (SHELA). Results: Out of 228 stool specimens collected, 30(13.2%) E. histolytica/E. dispar were observed by microscopic examination of which 6(2.6%) were trophozoite and 24 (10.5%) were cysts. From the total 30(13.2%) microscopically observed E. histolytica /E. dispar, PCR-SHELA detected 28(12.3%) E.dispar while no E.histolytica DNA was found. Infections with one or more intestinal parasites were common, 151 (66.2 %). By far the most common intestinal parasitic infection was Ascaris lumbricoides, 87 (38.2%) followed by Trichuria trichiura, 53(23.3%). Conclusion: Infection with E. histolytica was not found in all the stool samples examined. Neither the trophozoites nor the quadrinucleated cysts reported by microscopy were those of E. histolytica. Our finding suggests that among the patients studied, the commonly reported trophozoites and cysts belong to the non-pathogenic E. dispar, which requires no treatment at all. Therefore, the commonly reported complaints of diarrhea require alternative explanation since the routine diagnostic microscopy of amebiasis is unsatisfactory. [Ethiop.
In vitro Induction of Entamoeba histolytica Cyst-like Structures from Trophozoites
PLoS Neglected Tropical Diseases, 2010
Inhibition of encystment can be conceived as a potentially useful mechanism to block the transmission of Entamoeba histolytica under natural conditions. Unfortunately, amoeba encystment has not been achieved in vitro and drugs inhibiting the formation of cysts are not available. Luminal conditions inducing encystment in vivo are also unknown, but cellular stress such as exposure to reactive oxygen species from immune cells or intestinal microbiota could be involved. A role for certain divalent cations as cofactors of enzymes involved in excystment has also been described. In this study, we show that trophozoite cultures, treated with hydrogen peroxide in the presence of trace amounts of several cations, transform into small-sized spherical and refringent structures that exhibit resistance to different detergents. Ultrastructural analysis under scanning and transmission electron microscopy revealed multinucleated structures (some with four nuclei) with smooth, thick membranes and multiple vacuoles. Staining with calcofluor white, as well as an ELISA binding assay using wheat germ agglutinin, demonstrated the presence of polymers of N-acetylglucosamine (chitin), which is the primary component of the natural cyst walls. Over-expression of glucosamine 6-phosphate isomerase, likely to be the rate-limiting enzyme in the chitin synthesis pathway, was also confirmed by RT-PCR. These results suggest that E. histolytica trophozoites activated encystment pathways when exposed to our treatment. Citation: Aguilar-Díaz H, Díaz-Gallardo M, Laclette JP, Carrero JC (2010) In vitro Induction of Entamoeba histolytica Cyst-like Structures from Trophozoites. PLoS Negl Trop Dis 4(2): e607.