Disease relevance of Amebiasis

• Two forms of amoebiasis are recognized: luminal amoebiasis where no clinical signs or symptoms are apparent, and invasive amoebiasis where the trophozoites invade the intestinal mucosa to produce dysentery or amoeboma, and can spread in blood to give extraintestinal lesions such as liver abscess [1].
• Tinidazole has been reported to be highly effective against trichomoniasis, giardiasis and amoebiasis [2].
• These data indicate that small peptides derived from the galactose-binding adhesin administered by the parenteral or oral route can provide protection against amebic liver abscess and should be considered as components of a subunit vaccine against invasive amoebiasis [3].
• A 3-year-old boy with hepatopulmonary amebiasis treated with chloroquine phosphate for 20 days subsequently was found to have three brain abscesses and responded to prolonged combined therapy with metronidazole and chloroquine phosphate [4].
• In both tests all sera of patients with invasive amebiasis reacted to recEh-P1 whereas none of those collected from healthy controls, including individuals with noninvasive amebiasis, or from patients suffering from bacterial or protozoan infections unrelated to E. histolytica did so [5].

High impact information on Amebiasis

• Among patients with invasive amebiasis from Durban, Republic of South Africa; San Diego, Calif; Mexico City, Mexico; and St Louis, Mo, 53 (82%) of 65 had antibodies to SREHP [6].
• The observation that a histolytic cysteine proteinase gene is present only in pathogenic isolates of E. histolytica suggests that this aspect of virulence in amebiasis is genetically predetermined [7].
• Immunological studies from this population have shown that protection from amebiasis is associated with mucosal anti-E. histolytica Gal/GalNAc lectin antibodies, suggesting that a vaccine is an achievable goal [8].
• The latter assay proved capable of detecting amoebic antigens in the polyethylene glycol precipitates of sera from 21 of 21 patients with amoebiasis (and none of 22 control subjects) [9].
• Use of bisacodyl suppository in the diagnosis of amoebiasis [10].

Chemical compound and disease context of Amebiasis

• Metronidazole is currently approved for use against Trichomonas infection and amebiasis [11].
• In an attempt to investigate the relationship between the cleavage of complement components C3 and C5 and the pathogenesis of amebiasis, we investigated the production of the anaphylatoxins C3a and C5a, which have diverse effects on the host immune response [12].
• In this review, Sam Stanley Jr discusses why a vaccine for amebiasis may be feasible, and describes the recent development of several promising recombinant E. histolytica antigen-based parenteral and oral vaccine candidates [13].
• By blast search we found in Entamoeba histolytica, the protozoan responsible for human amoebiasis, two genes (Ehclc-A and Ehclc-B) encoding for putative polypeptides with 25-30% identity to ClC chloride channels of several organisms [14].
• The E. histolytica galactose/N-acetyl-D-galactosamine-inhibitable lectin (Gal-lectin), an immunogenic surface molecule involved in colonization and invasion, is a promising vaccine candidate against amoebiasis [15].

Biological context of Amebiasis

• A recombinant trpE fusion protein containing the tandem repeats of SREHP was recognized by immune serum from a patient with amebiasis, demonstrating that SREHP is a naturally immunogenic protein [16].
• In an analysis of the molecular factors triggering amebiasis, we investigated the chemotaxis of Entamoeba histolytica toward tumor necrosis factor (TNF) in vitro, using quantitative imaging techniques [17].
• Intestinal lumen and mucosal microclimate H+ and NH3 concentrations as factors in the etiology of experimental amebiasis [18].
• Crude extracts of Fasciola gigantica adult worms, when used as an antigen in indirect hemagglutination (IHA) and counterimmunoelectrophoresis (CIEP) tests, detected all independently diagnosed human F. gigantica and F. hepatica infections but cross-reacted with sera of patients with schistosomiasis and amebiasis [19].
• The complexes 2a-7a, 9a and 10a showed less IC50 value than metronidazole, the drug of choice for amoebiasis [20].

Anatomical context of Amebiasis

• The results suggest that IFN-gamma may participate in protection against amebiasis infection through the activity of mediators released by lymphocytes during infection [21].
• Anti-tag antibodies, monoclonal antibodies against the EhCP112 and sera from human patients with amoebiasis recognized rEhCP112. rEhCP112 digested gelatin, collagen type I, fibronectin and haemoglobin; it destroyed MDCK cell monolayers and bound to red blood cells [22].
• Using a histamine release assay by passive sensitized human leukocytes, a significant increase of Entamoeba histolytica induced IgE-mediated histamine liberation was found in basophils sensitized with sera from patients with amoebiasis as compared to those of control groups [23].
• As macrophages are involved in host defense in amebiasis, we determined whether soluble amebic lysates (Eh) can modulate TNF-alpha, IL-1 alpha/beta and c-fos gene expression in naive bone marrow-derived macrophages (BM delta) [24].

Gene context of Amebiasis

• These results suggest that the TNF-alpha-stimulating region of native Gal-lectin is a potent stimulus of IFN-gamma-primed BMM for NO production, which is essential for host defense against amebiasis [25].
• Entamoeba histolytica cysteine proteinases with interleukin-1 beta converting enzyme (ICE) activity cause intestinal inflammation and tissue damage in amoebiasis [26].
• The aim of this study was to characterize the specific interactions occurring between E. histolytica secreted cysteine proteinases and colonic mucin as a model to examine the initial events of invasive amebiasis [27].
• Other DQB1 and DRB1 alleles (DQB1*0202, DQB1*0301, and DRB1*0701) were not associated with any of the clinical outcomes related to amebiasis [28].
• The increase in human intestinal IL-1beta and IL-8 in response to invasive amebiasis was confirmed by enzyme-linked immunosorbent assays specific for human IL-1beta and IL-8 [29].

Analytical, diagnostic and therapeutic context of Amebiasis

• Tinidazole in the treatment of trichomoniasis, giardiasis and amoebiasis. Report of a multicentre study [30].
• Complete resolution of generalized eczema craquelé after treatment with metronidazole of occult amebiasis [31].
• Sera from patients suffering from invasive amoebiasis also immunoprecipitated 32P-labeled, purified LPG and could immunostain this molecule in Western blots [32].
• Sera of amebiasis patients and rabbits immunized with killed Entamoeba histolytica were tested for anti-amebic antibodies by the IHA test and for auto-antibodies by the complement fixation test, using the antigens prepared from extracts of human liver and rabbit liver [33].
• These results suggested that clone 1223 is promising in terms of providing a useful antigen for the accurate serodiagnosis of amoebiasis and that the gene encodes a putative alcohol dehydrogenase of E. histolytica [34].

References