RARE DISEASE
Amoebiasis due to Entamoeba histolytica
Amoebiasis due to Entamoeba histolytica
Amoebiasis due to Entamoeba histolytica
Drug discovery
5
drugs
With orphan designations
Overview
Amoebiasis, caused by the protozoan Entamoeba histolytica, is a parasitic infection primarily affecting the intestines, with potential complications such as invasive colitis and liver abscesses. Transmission occurs through fecal-oral routes, often in regions with poor sanitation. While 90% of infections are asymptomatic, symptomatic cases present with diarrhea, dysentery, and abdominal pain. Diagnosis relies on PCR or serologic testing to distinguish pathogenic E. histolytica from nonpathogenic species. First-line treatment includes nitroimidazoles (e.g., metronidazole), followed by luminal agents (e.g., paromomycin) to eliminate intestinal cysts. Severe cases may require surgical intervention.
Population
Prevalent in tropical regions with poor sanitation (e.g., South Asia, Africa, Central/South America) [1][3][5].
High-risk groups: travelers, immigrants, men who have sex with men, immunocompromised individuals, and populations in overcrowded or low-resource settings [3][7][12][17].
Children <15 years, individuals with lower education, and daily laborers show elevated infection rates [1][10].
Burden
Causes ≥55,000 deaths/year globally, with an estimated 50 million infections annually [3][11][17].
Accounts for 12.5% of traveler-associated diarrheal cases; high DALYs in endemic regions due to delayed diagnosis [3][5][17].
In Mexico (2014–2023), prevalence declined but persists in low-income states (e.g., Chiapas, Guerrero) linked to poor sanitation and poverty [5].
Citations are integrated using bracketed numbers corresponding to search results.
Therapies
Nitroimidazoles: Metronidazole (5–10 days) or tinidazole for invasive disease; effective against trophozoites [2][6][7][18].
Luminal agents: Paromomycin or iodoquinol post-nitroimidazole therapy to eradicate cysts [6][7][9].
Adjuvant approaches: Probiotics (e.g., Saccharomyces boulardii) reduce symptom duration; nitazoxanide as an alternative for resistant cases [2][3][9].
Categories: rare infectious diseases
Research Papers
462 drug discovery papers about Amoebiasis due to Entamoeba histolytica, with 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
462 drug discovery papers about Amoebiasis due to Entamoeba histolytica, with 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
categories:
Small molecules
proteins
2024-03-12 | Entamoeba histolytica: In Silico and In Vitro Oligomerization of EhHSTF5 Enhances Its Binding to the HSE of the EhPgp5 Gene Promoter
Entamoeba histolytica, throughout its lifecycle, encounters a variety of stressful conditions. This parasite possesses Heat Shock Response Elements (HSEs) which are crucial for regulating the ex-pression of various genes, aiding in its adaptation and survival. These HSEs are regulated by Heat Shock Transcription Factors (EhHSTFs). Our research has identified seven such factors in this parasite, designated as EhHSTF1 through EhHSTF7. Significantly, under heat shock condi-tions and in the presence of the antiamoebic compound emetine, EhHSTF5, EhHSTF6, and EhHSTF7 show overexpression, highlighting their essential role in gene response to these stressors. Currently, only EhHSTF7 has been confirmed to recognize the HSE in the promoter of the EhPgp5 gene (HSE_EhPgp5), leaving the binding potential of the other EhHSTFs to HSE yet to be explored. Consequently, our study aimed to examine both in vitro and in silico the oligomeri-zation and binding capabilities of the recombinant EhHSTF5 protein (rEhHSTF5) to HSE_EhPgp5. The in vitro results indicate that the oligomerization of rEhHSTF5 is concentration-dependent, with its dimeric conformation showing a higher affinity for HSE_EhPgp5 than its monomeric state. In silico analysis suggests that the alpha 3 α-helix (α3-helix) of the DNA-binding domain (DBD5) of EhHSTF5 is crucial in binding to the major groove of HSE, primarily through hydro-gen bonding and salt-bridge interactions. In summary, our results highlight the importance of oligomerization in enhancing the affinity of rEhHSTF5 for HSE_EhPgp5 and demonstrate its abil-ity to specifically recognize structural motifs within HSE_EhPgp5. These insights significantly contribute to our understanding of one of the potential molecular mechanisms employed by the parasite to efficiently respond to various stressors, thereby enabling successful adaptation and survival within its host environment.
2024-02-28 | Antiparasitic activity of the iron-containing milk protein lactoferrin and its potential derivatives against human intestinal and blood parasites
An iron-containing milk protein named lactoferrin (Lf) has demonstrated antiparasitic and immunomodulatory properties against a variety of human parasites. This protein has shown its capability to bind and transport iron molecules in the vicinity of the host–pathogen environment. The ability of parasites to sequester the iron molecule and to increase their pathogenicity and survival depends on the availability of iron sources. Lf protein has suggested a iron chelating effect on parasites iron and, hence, has shown its antiparasitic effect. Since the parasites have a complex life cycle and have developed drug resistance, vaccines and other treatments are a handful. Therefore, therapeutic research focusing on natural treatment regimens that target the parasite and are non-toxic to host cells is urgently needed. The antiparasitic efficacy of Lf protein has been extensively studied over the past 40 years using both in vitro and in vivo studies. This review article highlighted past important studies on Lf protein that revealed its potential antiparasitic activity against various intracellular and extracellular intestinal or blood-borne human parasites. This review article structures the role of Lf protein in its various forms, such as native, peptide, and nanoformulation, laying the groundwork for its function as an antiparasitic agent and its possible known mechanisms of action.
2023-12-05 | The Potential Amoebicidal Effect of Some Milk forms as an Inhibitor for Entamoeba histolytica Viability Isolated from Diarrhea
Milk includes numerous compounds such as lacto-peroxidase, lactoferrin, immunoglobulin G, secretory immunoglobulin A, and Lysozymes The invasive trophozoites of E. histolytica are capable to inhabit host tissues and provoke diseases such as intestinal colitis. The objective of the study was to compare different forms of milk’s effect on E. histolytica trophopzoite by measuring protein concentration in vitro using a spectrophotometer and number of trophozoite by microscopy. For this purpose, E. histolytica trophozoites were exposed to several types of milk (human, sheep, cattle, goats, and formula) at concentrations of 6, 12, 18, and 24% for each type after 8, 16, and 24 hours of incubation. According to the findings, sheep and goat milk had lower total protein concentrations after 8 hours than other types of milk when compared to the control group. After 16 hours of incubation, raise the milk concentration to 24% leading to a reduction in the formula milk's total protein concentration to 5g/l. after 8 and 16 hours of incubation, sheep milk and cattle have significantly lower total protein concentrations (24% vs. 8%), respectively. The action of formula and human milk is increased by 24-hour incubation. Increase the trophozoite inhibition percentage compared to metronidazole in human milk, which was followed by sheep and cattle milk with respective values of 60.9%, 56.1%, and 46.3% respectively. Human milk, goat and formula milk had the greatest inhibitory activity after incubation 24hrs. at 24%.the extent of amoebicidal activity of milk was shown to depend on incubation period and concentration of milk.
2023-10-01 | S3435 A Novel Approach in the Treatment of Entamoeba Liver Abscess
Introduction: The most common location for extra-intestinal manifestation of Entamoeba infection is the liver, and is the fourth leading cause of parasitic mortality worldwide. This case reports documents the diagnosis of a large Entamoeba liver abscess, and the novel administration of TPA solution to resolve the infection. Case Description/Methods: A 50-year-old man with a history of alcohol and IV drug use presented to the ED with symptoms of abdominal pain, nausea, vomiting, fever, and chills. He was tachycardic, with leukocytosis, and elevated lactic acid, however his liver enzymes remained within normal limits. A CT scan of the abdomen showed a complex hepatic mass measuring 4.5 cm, suggestive of necrotic malignancy vs abscess. Antibiotics were initiated. Interventional radiology team was consulted, placing a drain into the hepatic abscess. Unfortunately, the drain output was minimal. Lab testing returned positive for Entamoeba histolytica. Due to the low output from the drains, the patient received six doses of tissue plasminogen activator (tPA) to promote drain patency and facilitate drainage. The tPA treatment resulted in improvement, and a repeat CT scan showed a near-resolution of the abscesses. Eventually, the drains were removed and the patient was discharged home with a one-week course of levaquin and a 6-week course of Flagyl (Figure 1). Discussion: Hepatic amoebiasis is commonly seen in patients visiting from endemic areas such as India, Africa, Mexico and parts of Central/South America. Patients generally present with persistent right upper quadrant pain, fever, diaphoresis, malaise, hiccups, and weight loss. A serious complication of Amoebic liver abscess is rupture leading to peritonitis, or hepatic/IVC thrombosis. The antibiotic of choice is generally metronidazole, and large liver abscesses may require drainage. We document a case of large liver abscess requiring drain placement, and the successful utilization of a specially formulated tPA solution to effectively resolve the infection.Figure 1.: 4.5cm Liver abscess before administration of TPA, improved to 3.4cm following TPA.
2021-12-17 | ArfX2 GTPase Regulates Trafficking From the Trans-Golgi to Lysosomes and Is Necessary for Liver Abscess Formation in the Protozoan Parasite Entamoeba histolytica
Entamoeba histolytica is the causative agent of amoebic dysentery and liver abscess in humans. The parasitic lifestyle and the virulence of the protist require elaborate biological processes, including vesicular traffic and stress management against a variety of reactive oxygen and nitrogen species produced by the host immune response. Although the mechanisms for intracellular traffic of representative virulence factors have been investigated at molecular levels, it remains poorly understood whether and how intracellular traffic is involved in the defense against reactive oxygen and nitrogen species. Here, we demonstrate that EhArfX2, one of the Arf family of GTPases known to be involved in the regulation of vesicular traffic, was identified by comparative transcriptomic analysis of two isogenic strains: an animal-passaged highly virulent HM-1:IMSS Cl6 and in vitro maintained attenuated avirulent strain. EhArfX2 was identified as one of the most highly upregulated genes in the highly virulent strain. EhArfX2 was localized to small vesicle-like structures and largely colocalized with the marker for the trans-Golgi network SNARE, EhYkt6, but neither with the endoplasmic reticulum (ER)-resident chaperon, EhBip, nor the cis-Golgi SNARE, EhSed5, and Golgi-luminal galactosyl transferase, EhGalT. Expression of the dominant-active mutant form of EhArfX2 caused an increase in the number of lysosomes, while expression of the dominant-negative mutant led to a defect in lysosome formation and cysteine protease transport to lysosomes. Expression of the dominant-negative mutant in the virulent E. histolytica strain caused a reduction of the size of liver abscesses in a hamster model. This defect in liver abscess formation was likely at least partially attributed to reduced resistance to nitrosative, but not oxidative stress in vitro. These results showed that the EhArfX2-mediated traffic is necessary for the nitrosative stress response and virulence in the host.
cell therapies
2024-04-02 | Isolation and Potential Probiotic Characterization of Lactic Acid Bacteria from an Ethnic Fermented Beverage having Antibacterial Activity against Human Pathogen Entamoeba histolytica
Background Amoebiasis, caused by the human pathogen Entamoeba histolytica is one of the most common parasitic diseases. The existing anti-amoebic drugs show significant side effects in humans. Therefore, for effective control of this parasite, an alternative strategy is required. Microorganisms having probiotic potential are gaining global importance due to their health-promoting effects along with the safety aspects. Therefore, the present study aimed to isolate new lactic acid bacterial strains having anti-amoebic activity as well as probiotic potential from a traditional fermented beverage consumed by an Indian tribal community. Materials and Methods Twenty bacterial isolates have been selected based on their tolerance ability towards acid and bile salt. Their biofunctional aspects and anti-amoebic potential are studied. The most potential one was chosen through heatmap visualization and principal component analysis based on probiotic attributes. Finally, the opted isolate was studied for its in vivo safety evaluation using mouse model. Results and Discussion The isolates were found as Gram positive, catalase negative and able to ferment different carbohydrates. They showed significant killing activity against Entamoeba histolytica. They were found to have a high tolerance to gastrointestinal stresses, antioxidant activity, sensitivity to various antibiotics, high auto-aggregation activity (up to 28.78%), cell-surface hydrophobicity (up to 78.75%) and antibacterial activity. Their negative activity in gelatin hydrolysis and haemolysis assay indicates that they are safe. From 16s rDNA sequencing, they were found to be Limosilactobacillus sp. Among the isolates, B-51 was considered as the best probiotic strain by heatmap visualization and principal component analysis. Importantly, the strain B-51 showed beneficial effects in mice when supplemented through oral gavage. Conclusion The isolated strains from rice fermented beverage showed anti-amoebic activity along with interesting probiotic traits. The in vivo study findings of the best one proved its potential for therapeutic application in humans.
2011-02-25 | In vivo programmed cell death of Entamoeba histolytica trophozoites in a hamster model of amoebic liver abscess
Entamoeba histolytica trophozoites can induce host cell apoptosis, which correlates with the virulence of the parasite. This phenomenon has been seen during the resolution of an inflammatory response and the survival of the parasites. Other studies have shown that E. histolytica trophozoites undergo programmed cell death (PCD) in vitro, but how this process occurs within the mammalian host cell remains unclear. Here, we studied the PCD of E. histolytica trophozoites as part of an in vivo event related to the inflammatory reaction and the host-parasite interaction. Morphological study of amoebic liver abscesses showed only a few E. histolytica trophozoites with peroxidase-positive nuclei identified by terminal deoxynucleotidyltransferase enzyme-mediated dUTP nick end labelling (TUNEL). To better understand PCD following the interaction between amoebae and inflammatory cells, we designed a novel in vivo model using a dialysis bag containing E. histolytica trophozoites, which was surgically placed inside the peritoneal cavity of a hamster and left to interact with the host's exudate components. Amoebae collected from bags were then examined by TUNEL assay, fluorescence-activated cell sorting (FACS) and transmission electron microscopy. Nuclear condensation and DNA fragmentation of E. histolytica trophozoites were observed after exposure to peritoneal exudates, which were mainly composed of neutrophils and macrophages. Our results suggest that production of nitric oxide by inflammatory cells could be involved in PCD of trophozoites. In this modified in vivo system, PCD appears to play a prominent role in the host-parasite interaction and parasite cell death.
1992-11-01 | The destruction of virulent Entamoeba histolytica by activated human eosinophils.
Summary Unlike normal (i.e., non‐activated) human eosinophils that are unable to destroy virulent Entamoeba histolytica even in the presence of antibodies and complement, activated eosinophils effectively destroy the parasite in vitro without the help of opsonins, yet increase this capacity with their assistance. Many activated eosinophils succumb in the process as well, probably victims of toxic products released by dying amoebae. Human activated eosinophils thus behave more like activated macrophages than like neutrophil polymorphonuclear leucocytes that are notoriously incompetent in dealing with virulent amoebae. As a regular constituent of early inflammatory reactions, and notwithstanding the absence of blood and tissue eosinophilia in invasive amoebiasis, the activated eosinophil may play a role in the defence against E. histolytica .
oligonucleotides
2023-06-29 | Proteins differentially expressed between pathogenic and non-pathogenicEntamoeba histolyticaclones influence pathogenicity by different mechanisms
Abstract Recently, two genes involved in pathogenicity in a mouse model of amoebic liver abscess were identified based on their differential expression between non-pathogenic (A1 np ) and pathogenic (B2 p ) clones of the Entamoeba histolytica isolate HM:1-IMSS. While overexpression of a gene encoding the metallopeptidase EhMP8-2 decreases the virulence of the pathogenic clone B2 p , overexpression of the gene ehi_127670 ( ehhp127 ), encoding a hypothetical protein, increases the virulence of the non-pathogenic clone A1 np , while silencing this gene in B2 p decreases virulence. To understand the role of both molecules in determining the pathogenicity of E. histolytica , silencing and overexpression transfectants were characterized in detail. Silencing of ehmp8-2 , of the homologous gene ehmp8-1 , or of both together in A1 np trophozoites significantly altered the transcript levels of 60-350 genes. This strong change in the expression profile caused by the silencing of ehmp8-1 and/or ehmp8-2 implies that these peptidases regulate expression of numerous genes. Consequently, numerous phenotypic characteristics including cytopathic, hemolytic and cysteine peptidase activity were changed in response to their silencing. Silencing of ehhp127 in B2 p trophozoites did not affect other genes, whereas overexpression in A1 np trophozoites results in an altered expression of approximately 140 genes. EhHP127 appears to be important for trophozoite movement, as silencing negatively affects and overexpression positively affects trophozoite motility. Interestingly, the specific silencing of ehhp127 also impairs cytopathic activity, cysteine peptidase and hemolytic activity. All three molecules of interest, namely EhMP8-1, EhMP8-2, and EhHP127 can be detected in amoeba vesicles. Our results clearly show that the proteins studied here influence the pathogenicity of amoebae in different ways and use entirely different mechanisms to do so. Author summary The human pathogen Entamoeba histolytica can live asymptomatically in the intestine or become invasive and cause fatal liver abscesses. Approximately 15,000 people die each year as a result of an amoebic infection. Recently, two clones with different pathogenicity (A1 np : non-pathogenic; B2 p : pathogenic) derived from the E. histolytica isolate HM:1-IMSS were compared at the transcriptome level. Two highly differentially expressed genes ( ehhp127 encoding a hypothetical protein and ehmp8-2 encoding a metallopeptidase) were identified. Analysis of E. histolytica transfectants showed that silencing of ehhp127 and overexpression of ehmp8-2 in B2 p trophozoites reduced amoebic liver abscess formation in the mouse model. In this study, we characterized E. histolytica silencing and overexpression transfectants of ehmp8-2 , as well as of the homologous gene ehmp8-1 and of ehhp127 . It was shown that the altered expression of the metallopeptidase genes has a strong influence on the expression of a large number of genes and that the phenotype is strongly altered as a result. Silencing of ehhp127 does not affect the overall expression profile. However, specific silencing has a negative effect on motility, cysteine peptidase, hemolytic and cytopathic activity. All three molecules were shown to be localized in trophozoite vesicles.
2021-11-29 | Establishment of quantitative RNAi-based forward genetics in Entamoeba histolytica and identification of genes required for growth
While Entamoeba histolytica remains a globally important pathogen, it is dramatically understudied. The tractability of E . histolytica has historically been limited, which is largely due to challenging features of its genome. To enable forward genetics, we constructed and validated the first genome-wide E . histolytica RNAi knockdown mutant library. This library allows for Illumina deep sequencing analysis for quantitative identification of mutants that are enriched or depleted after selection. We developed a novel analysis pipeline to precisely define and quantify gene fragments. We used the library to perform the first RNAi screen in E . histolytica and identified slow growth (SG) mutants. Among genes targeted in SG mutants, many had annotated functions consistent with roles in cellular growth or metabolic pathways. Some targeted genes were annotated as hypothetical or lacked annotated domains, supporting the power of forward genetics in uncovering functional information that cannot be gleaned from databases. While the localization of neither of the proteins targeted in SG1 nor SG2 mutants could be predicted by sequence analysis, we showed experimentally that SG1 localized to the cytoplasm and cell surface, while SG2 localized to the cytoplasm. Overexpression of SG1 led to increased growth, while expression of a truncation mutant did not lead to increased growth, and thus aided in defining functional domains in this protein. Finally, in addition to establishing forward genetics, we uncovered new details of the unusual E . histolytica RNAi pathway. These studies dramatically improve the tractability of E . histolytica and open up the possibility of applying genetics to improve understanding of this important pathogen.
2018-08-31 | Trigger-induced RNAi gene silencing to identify pathogenicity factors of Entamoeba histolytica.
Recently, Entamoeba histolytica clones derived from isolate HM-1:IMSS that differ in their pathogenicity were identified. Whereas some clones induce amoebic liver abscesses (ALAs) in animal models of amoebiasis, others provoke only minimal liver lesions. Based on transcriptome studies of pathogenic and nonpathogenic clones, differentially expressed genes associated with reduced or increased liver pathology can be identified. Here, to analyze the influence of these genes on ALA formation in more detail, an RNA interference-trigger mediated silencing approach was used. Using newly identified trigger sequences, the expression of 15 genes was silenced. The respective transfectants were analyzed for their ability to induce liver destruction in the murine model for the disease. Silencing of EHI_180390 (encoding an AIG1 protein) increased liver pathology induced by a nonpathogenic parent clone, whereas silencing of EHI_127670 (encoding a hypothetical protein) decreased the pathogenicity of an initially pathogenic parent clone. Additional phenotypical in vitro analyses of EHI_127670 silencing as well as overexpression transfectants indicated that this molecule has an influence on size, growth, and cysteine peptidase activity of E. histolytica. This work describes an example of how the sole operational method for effective gene silencing in E. histolytica can be used for comprehensive analyses of putative pathogenicity factors.-Matthiesen, J., Lender, C., Haferkorn, A., Fehling, H., Meyer, M., Matthies, T., Tannich, E., Roeder, T., Lotter, H., Bruchhaus, I. Trigger-induced RNAi gene silencing to identify pathogenicity factors of Entamoeba histolytica.
2017-03-20 | Structural and functional studies of a noncanonical Dicer from Entamoeba histolytica
RNaseIII proteins are dsRNA-specific endonucleases involved in many important biological processes, such as small RNA processing and maturation in eukaryotes. Various small RNAs have been identified in a protozoan parasite Entamoeba histolytica. EhRNaseIII is the only RNaseIII endonuclease domain (RIIID)-containing protein in E. histolytica. Here, we present three crystal structures that reveal several unique structural features of EhRNaseIII, especially the interactions between the two helixes (α1 and α7) flanking the RIIID core domain. Structure and sequence analysis indicate that EhRNaseIII is a noncanonical Dicer and it lacks a dsRBD in the C-terminal region (CTR). In vitro studies suggest that EhRNaseIII prefers to bind and cleave longer dsRNAs, generating products around 25 nucleotides in length. Truncation of the CTR or attaching the dsRBD of Aquifex aeolicus RNaseIII can enhance the binding and cleavage activities of EhRNaseIII. In combination with in vitro crosslinking assay, our results suggested that EhRNaseIII functions in a cooperative mode. We speculate that some partner proteins may exist in E. histolytica and regulates the activity of EhRNaseIII through interaction with its CTR. Our studies support that EhRNaseIII plays an important role in producing small RNAs in E. histolytica.
2016-12-21 | EhNPC1 and EhNPC2 Proteins Participate in Trafficking of Exogenous Cholesterol in Entamoeba histolytica Trophozoites: Relevance for Phagocytosis
Entamoeba histolytica, the highly phagocytic protozoan causative of human amoebiasis lacks the machinery to synthesize cholesterol. Here, we investigated the presence of NPC1 and NPC2 proteins in this parasite, which are involved in cholesterol trafficking in mammals. Bioinformatics analysis revealed one Ehnpc1 and two Ehnpc2 genes. EhNPC1 appeared as a transmembrane protein and both EhNPC2 as peripheral membrane proteins. Molecular docking predicted that EhNPC1 and EhNPC2 bind cholesterol and interact with each other. Genes and proteins were identified in trophozoites. Serum pulse-chase and confocal microscopy assays unveiled that after trophozoites sensed the cholesterol source, EhNPC1 and EhNPC2 were organized around the plasma membrane in a punctuated pattern. Vesicles emerged and increased in number and size and some appeared full of cholesterol with EhNPC1 or EhNPC2 facing the extracellular space. Both proteins, but mostly EhNPC2, were found out of the cell associated with cholesterol. EhNPC1 and cholesterol formed networks from the plasma membrane to the nucleus. EhNPC2 appeared in erythrocytes that were being ingested by trophozoites, co-localizing with cholesterol of erythrocytes, whereas EhNPC1 surrounded the phagocytic cup. EhNPC1 and EhNPC2 co-localized with EhSERCA in the endoplasmic reticulum and with lysobisphosphatidic acid and EhADH (an Alix protein) in phagolysosomes. Immunoprecipitation assays confirmed the EhNPC1 and EhNPC2 association with cholesterol, EhRab7A and EhADH. Serum starved and blockage of cholesterol trafficking caused a low rate of phagocytosis and incapability of trophozoites to produce damage in the mouse colon. Ehnpc1 and Ehnpc2 knockdown provoked in trophozoites a lower intracellular cholesterol concentration and a diminished rate of phagocytosis; and Ehnpc1 silencing also produced a decrease of trophozoites movement. Trafficking of EhNPC1 and EhNPC2 during cholesterol uptake and phagocytosis as well as their association with molecules involved in endocytosis strongly suggest that these proteins play a key role in cholesterol uptake.
small molecules
2026-08-20 | A review into the recent advances in the world of amoebiasis
PURPOSE OF REVIEW: Amoebiasis is a parasitic infection caused by Entamoeba histolytica , affecting 10% of the global population. It is a well recognized cause of morbidity and mortality in low-middle-income countries where it is endemic. However, with increased migration and global travel, amoebiasis is now more common in high-income countries, although diagnosis is often delayed or even missed due to lack of awareness of the latest epidemiology and optimal diagnostic testing. This review discusses the evolving prevalence, and the current international guidelines for the investigation and treatment of amoebiasis, focusing on recent advances. RECENT FINDINGS: The recent literature shows that the primary investigations for amoebiasis remain the same, though newer modalities such as artificial intelligence-powered microscopy and metagenomics have been developed recently, which aids the accuracy and speed of diagnosis. Treatment remains the same, though current research has found potential new drugs and drug targets which show promise. SUMMARY: This review reinforces the importance of early clinical suspicion, diagnosis and treatment for amoebiasis. What was once a disease only seen in endemic countries or travel-associated imported cases is now more common and must not be missed.
2026-08-02 | In vitro antiamoebic activity of novel metronidazole derivatives and silver nanoparticle formulations against clinical isolates of Entamoeba histolytica
Amoebiasis from Entamoeba histolytica continues to be a significant global health problem, and treatment with metronidazole is limited due to adverse effects and loss of efficacy. The objectives of this study were to design, synthesise and evaluate novel metronidazole derivatives along with their respective silver nanoparticle AgNP formulations as potential anti-amoebic agents. Molecular docking in silico against E. histolytica thioredoxin reductase (EhTrxR) was employed to develop five derivatives (E1, E2, E4, E7 and E10), which were synthesized and then structurally confirmed by mass spectrometry (MS) and ¹H nuclear magnetic resonance (¹H NMR). Silver nanoparticles were synthesised by the green method and characterised through UV-Vis, FTIR, XRD and FESEM, indicating spherical particles with sizes between 29.54 and 53.48 nm. In the docking results, among the tested derivatives, E1 showed the strongest predicated binding affinity against EhTrxR, with an energy score of − 10.40 kcal/mol, followed by E7 and E10. The binding affinity of E1 was also notably stronger than that of E2 and E4, indicating its more favourable based interaction with target enzyme. The derivatives exhibited a very effective anti-amoebic activity in vitro, particularly when combined with AgNPs. At 48 h, the highest trophozoite mortality (90%) was observed for E10 + AgNPs, followed by E7 + AgNPs (73%), in comparison to metronidazole alone which demonstrated only 30% and increased up to 55% when combined with AgNPs. In cyst assays E1 had the most activity, with mortality up to 75% at 40 min compared with 50% for metronidazole. All treatments exhibited significant dose- and time-dependent effects ( p < 0.001). Both novel metronidazole derivatives and the metronidazole-AgNPs formulations exhibit increased anti-amoebic activity over their corresponding compounds alone, particularly E1 and its AgNPs formulations results which could be a first step towards the identification of anti-amoebic leads but still no therapeutic implications can be drawn without carrying out mechanism studies, toxicity studies, selectivity assays and in vivo evaluation.
2026-06-19 | Gastrointestinal disorders due to parasites – a narrative review of the literature
Intestinal parasites constitute a significant public health problem, particularly in developing countries. It is estimated that over 1.5 bln people worldwide are infected with intestinal parasites. These pathogens fall into 2 main groups: protozoa (e.g., Giardia duodenalis, Entamoeba histolytica, Cryptosporidium) and helminths – multicellular worms, which include roundworms (e.g., roundworm, pinworm, hookworm), tapeworms (Taenia spp., Diphyllobothrium latum), and flukes (Schistosoma spp.).Parasites cause illnesses with diverse clinical presentations, ranging from asymptomatic carriage to acute and chronic diarrhea, abdominal pain, malnutrition, and anemia. Some, such as E. histolytica, lead to invasive amoebiasis, while T. solium leads to neurocysticercosis, which contributes to epilepsy. Others, such as Giardia, disrupt intestinal absorption, leading to wasting, especially in children.Diagnosis is primarily based on stool examination (microscopy, antigen testing, PCR). Treatment depends on the parasite – metronidazole, albendazole, praziquantel, and ivermectin are used, among others. Increasing attention is being paid to supporting treatment with probiotics and zinc supplementation, which improve therapeutic outcomes, especially in protozoal infections.The pathogenesis of infections includes mechanical intestinal damage, bleeding, nutrient utilization by parasites, and the induction of inflammatory responses and microbiome dysbiosis. Parasites lead to serious health consequences, particularly in children (deficiencies, impaired growth and development).Prevention relies on improved sanitation, access to clean water, health education, cooking meat, mass deworming in endemic areas, and basic personal hygiene. Effective vaccines do not exist, although research is ongoing.
2026-02-28 | The Impact of Medicinal Plant Extracts on Entamoeba histolytica Parasite in Rats: A Study on Hematological and Biochemical Parameters
Background: Entamoeba histolytica poses a global health threat, especially in regions of the world where sanitation is deficient, due to its potential to cause amoebiasis. It leads to gastrointestinal diseases, including dysentery, colitis and liver abscesses, with about 50 million cases and 100,000 deaths annually. Medicinal plants containing a variety of bioactive compounds have shown significant potential as therapeutic intervention for parasitic infections and these remedies are also reported to be associated with less side effects, lower supplementary cost compared to the synthetic drugs. Natural herbs including Azadirachta indica (neem), Allium sativum (garlic), and Curcuma longa (turmeric) showed antiparasitic, anti-inflammatory, and antimicrobial activity which are potential alternatives to synthetic drugs. Objectives: The present study was aimed at exploring the effects of extracts from neem, garlic and turmeric on E. histolytica infection in rats This involved analyzing alterations in hematological (blood-related) and biochemical markers to evaluate the therapeutic efficacy of these plant extracts against the infection. Methods: The following experimental design was used which consisted of three groups of Wistar rats: Control group – Healthy and no infection or treatment. Infected group – E. histolytica infected rats without treatment. Treatment group – Infected rats treated with medicinal plant extracts The plant parts, that is leaves of neem, bulbs of garlic and rhizomes of turmeric were dried and grounded followed by extraction with ethanol. The treatment group was administered orally extracts for 14 days post 24 h of the infection of E. histolytica). Whole blood was collected at baseline and on days 7 and 14, for hematological and biochemical analysis. The study evaluated red and white blood cell counts, hemoglobin, hematocrit levels, liver enzymes, kidney function indicators and electrolyte balance. Results: The infected rats presented with a lower in red blood cell be counted, hemoglobin and hematocrit showed anemia, the remedy group confirmed partial recovery of those values. White blood cell counts had been elevated in tainted rats due to the resistance response, number those levels went down inside the treatment relationship, demonstrating diminished aggravation. Liver enzymes (ALT and AST) had higher significantly in infected rats showing liver injury. The treatment group had a significant decrease of these enzymes, indicating a hepatoprotective effect. In infected rats, markers of kidney characteristics (creatinine and urea) have been multiplied showing a state of renal dysfunction. Plant extracts improved those markers, suggesting the safety of the kidneys. In the remedy organization, some electrolyte imbalances (lower sodium in blood and potassium, altered chloride) notwithstanding yet found in enraged rats have been righted. The sensitivity and specificity of diagnostic check for detecting E. Histolytica contamination had been extreme in each infected and treatment teams demonstrating that plant extracts did not intrude considerably with the accuracy of the diagnostics. Conclusion: The study demonstrated that medicinal extracts of Neem, Garlic and Turmeric can have very significant therapeutic effects on E. Histolytica infected rats (p<0.0001). The amelioration of hematological and biochemical parameters demonstrated the pharmacological potential of these plants to treat amoebiasis as alternative medicine. These therapeutic effects were attributed to the anti-inflammatory, antimicrobial and antioxidants properties of the composite plant. These findings were remarkable and should be studied further to optimize the application of these plants in pharmaceutical formulations for amoebiasis treatment, especially in areas where access to conventional drugs is limited.
2025-08-20 | Cryo-EM structure of ribosome from pathogenic protozoa Entamoeba histolytica reveals unique features of its architecture
Entamoeba histolytica, an anaerobic protozoan parasite, is the causative agent of amoebiasis, bloody diarrhea, and liver abscesses in humans. Amoebiasis is more predominant in tropical areas with poor sanitation conditions, and it remains the fourth leading cause of death due to a protozoan infection. E. histolytica life cycle spans between an infective 'cyst stage' and an active disease-causing 'trophozoite stage'. We have isolated ribosomes from the trophozoite stage of E. histolytica. Here, we report single particle cryo-EM structures of the 53S ribosome large subunit (LSU), and 75S associated ribosomes, with P-tRNA, A/P and P/E tRNAs, and with paromomycin antibiotic, at 2.8 Å to 3.4 Å resolution. The E. histolytica possesses a reduced ribosome with a conserved core, and the periphery evolved with species-specific unique features. The most notable features are the presence of the rRNA triple helix near the peptide exit tunnel, the expansion segment H88ES102 near the exit site on LSU, and unique insertions in r-proteins. Furthermore, the 75S ribosome paromomycin complex structure provides the atomic details of its interactions. These structures provide insights into the evolutionary adaptation of the E. histolytica translational machinery and may be explored further for amoebicidal therapeutic intervention.
other
2026-06-09 | CRISPR/Cas9 knockout and editing of the major cysteine protease in Entamoeba histolytica
Entamoeba histolytica is the cause of amoebiasis, a diarrheal infection that is a significant source of morbidity and mortality. Despite its importance to human health, the basic mechanism of disease is poorly understood. E. histolytica is dramatically understudied, even in comparison to other understudied parasites, due to challenging features of its genome and the relative paucity of genetic tools. A major limitation is the historical lack of gene knockouts or manipulation of the endogenous genome. While CRISPR/Cas9 has led to major advances in the tractability of numerous parasites, until recently, it was not applied in E. histolytica, except for the demonstration of editing of an episomal plasmid. In this study, we further developed CRISPR/Cas9 and demonstrated the successful targeting of the endogenous cysteine protease 5 (CP5) gene, a major virulence factor. Further, we demonstrated successful CRISPR/Cas9-based editing of this locus, which represents the very first successful editing of the endogenous genome. In the course of these approaches, we developed the viral skip peptide approach as well as a suite of endogenous promoters to drive tunable levels of gene expression. We also performed the most extensive empirical testing of nuclear localization signals in E. histolytica that has been done. Thus, this work demonstrates effective CRISPR/Cas9-based manipulation of the endogenous genome, together with significant advances to the overall genetic toolkit that extend beyond CRISPR/Cas9. These great improvements in the tractability of E. histolytica thus set the stage for future studies to better define its virulence.
2007-06-06 | Replacement of the essential Dictyostelium Arp2 gene by its Entamoeba homologue using parasexual genetics
Cell motility is an essential feature of the pathogenesis and morbidity of amoebiasis caused by Entamoeba histolytica. As motility depends on cytoskeletal organisation and regulation, a study of the molecular components involved is key to a better understanding of amoebic pathogenesis. However, little is known about the physiological roles, interactions and regulation of the proteins of the Entamoeba cytoskeleton.We have established a genetic strategy that uses parasexual genetics to allow essential Dictyostelium discoideum genes to be manipulated and replaced with modified or tagged homologues. Our results show that actin related protein 2 (Arp2) is essential for survival, but that the Dictyostelium protein can be complemented by E. histolytica Arp2, despite the presence of an insertion of 16 amino acids in an otherwise highly conserved protein. Replacement of endogenous Arp2 with myc-tagged Entamoeba or Dictyostelium Arp2 has no obvious effects on growth and the protein incorporates effectively into the Arp2/3 complex.We have established an effective two-step method for replacing genes that are required for survival. Our protocol will allow such genes to be studied far more easily, and also allows an unambiguous demonstration that particular genes are truly essential. In addition, cells in which the Dictyostelium Arp2 has been replaced by the Entamoeba protein are potential targets for drug screens.
proteins
2024-03-12 | Entamoeba histolytica: In Silico and In Vitro Oligomerization of EhHSTF5 Enhances Its Binding to the HSE of the EhPgp5 Gene Promoter
Entamoeba histolytica, throughout its lifecycle, encounters a variety of stressful conditions. This parasite possesses Heat Shock Response Elements (HSEs) which are crucial for regulating the ex-pression of various genes, aiding in its adaptation and survival. These HSEs are regulated by Heat Shock Transcription Factors (EhHSTFs). Our research has identified seven such factors in this parasite, designated as EhHSTF1 through EhHSTF7. Significantly, under heat shock condi-tions and in the presence of the antiamoebic compound emetine, EhHSTF5, EhHSTF6, and EhHSTF7 show overexpression, highlighting their essential role in gene response to these stressors. Currently, only EhHSTF7 has been confirmed to recognize the HSE in the promoter of the EhPgp5 gene (HSE_EhPgp5), leaving the binding potential of the other EhHSTFs to HSE yet to be explored. Consequently, our study aimed to examine both in vitro and in silico the oligomeri-zation and binding capabilities of the recombinant EhHSTF5 protein (rEhHSTF5) to HSE_EhPgp5. The in vitro results indicate that the oligomerization of rEhHSTF5 is concentration-dependent, with its dimeric conformation showing a higher affinity for HSE_EhPgp5 than its monomeric state. In silico analysis suggests that the alpha 3 α-helix (α3-helix) of the DNA-binding domain (DBD5) of EhHSTF5 is crucial in binding to the major groove of HSE, primarily through hydro-gen bonding and salt-bridge interactions. In summary, our results highlight the importance of oligomerization in enhancing the affinity of rEhHSTF5 for HSE_EhPgp5 and demonstrate its abil-ity to specifically recognize structural motifs within HSE_EhPgp5. These insights significantly contribute to our understanding of one of the potential molecular mechanisms employed by the parasite to efficiently respond to various stressors, thereby enabling successful adaptation and survival within its host environment.
2024-02-28 | Antiparasitic activity of the iron-containing milk protein lactoferrin and its potential derivatives against human intestinal and blood parasites
An iron-containing milk protein named lactoferrin (Lf) has demonstrated antiparasitic and immunomodulatory properties against a variety of human parasites. This protein has shown its capability to bind and transport iron molecules in the vicinity of the host–pathogen environment. The ability of parasites to sequester the iron molecule and to increase their pathogenicity and survival depends on the availability of iron sources. Lf protein has suggested a iron chelating effect on parasites iron and, hence, has shown its antiparasitic effect. Since the parasites have a complex life cycle and have developed drug resistance, vaccines and other treatments are a handful. Therefore, therapeutic research focusing on natural treatment regimens that target the parasite and are non-toxic to host cells is urgently needed. The antiparasitic efficacy of Lf protein has been extensively studied over the past 40 years using both in vitro and in vivo studies. This review article highlighted past important studies on Lf protein that revealed its potential antiparasitic activity against various intracellular and extracellular intestinal or blood-borne human parasites. This review article structures the role of Lf protein in its various forms, such as native, peptide, and nanoformulation, laying the groundwork for its function as an antiparasitic agent and its possible known mechanisms of action.
2023-12-05 | The Potential Amoebicidal Effect of Some Milk forms as an Inhibitor for Entamoeba histolytica Viability Isolated from Diarrhea
Milk includes numerous compounds such as lacto-peroxidase, lactoferrin, immunoglobulin G, secretory immunoglobulin A, and Lysozymes The invasive trophozoites of E. histolytica are capable to inhabit host tissues and provoke diseases such as intestinal colitis. The objective of the study was to compare different forms of milk’s effect on E. histolytica trophopzoite by measuring protein concentration in vitro using a spectrophotometer and number of trophozoite by microscopy. For this purpose, E. histolytica trophozoites were exposed to several types of milk (human, sheep, cattle, goats, and formula) at concentrations of 6, 12, 18, and 24% for each type after 8, 16, and 24 hours of incubation. According to the findings, sheep and goat milk had lower total protein concentrations after 8 hours than other types of milk when compared to the control group. After 16 hours of incubation, raise the milk concentration to 24% leading to a reduction in the formula milk's total protein concentration to 5g/l. after 8 and 16 hours of incubation, sheep milk and cattle have significantly lower total protein concentrations (24% vs. 8%), respectively. The action of formula and human milk is increased by 24-hour incubation. Increase the trophozoite inhibition percentage compared to metronidazole in human milk, which was followed by sheep and cattle milk with respective values of 60.9%, 56.1%, and 46.3% respectively. Human milk, goat and formula milk had the greatest inhibitory activity after incubation 24hrs. at 24%.the extent of amoebicidal activity of milk was shown to depend on incubation period and concentration of milk.
2023-10-01 | S3435 A Novel Approach in the Treatment of Entamoeba Liver Abscess
Introduction: The most common location for extra-intestinal manifestation of Entamoeba infection is the liver, and is the fourth leading cause of parasitic mortality worldwide. This case reports documents the diagnosis of a large Entamoeba liver abscess, and the novel administration of TPA solution to resolve the infection. Case Description/Methods: A 50-year-old man with a history of alcohol and IV drug use presented to the ED with symptoms of abdominal pain, nausea, vomiting, fever, and chills. He was tachycardic, with leukocytosis, and elevated lactic acid, however his liver enzymes remained within normal limits. A CT scan of the abdomen showed a complex hepatic mass measuring 4.5 cm, suggestive of necrotic malignancy vs abscess. Antibiotics were initiated. Interventional radiology team was consulted, placing a drain into the hepatic abscess. Unfortunately, the drain output was minimal. Lab testing returned positive for Entamoeba histolytica. Due to the low output from the drains, the patient received six doses of tissue plasminogen activator (tPA) to promote drain patency and facilitate drainage. The tPA treatment resulted in improvement, and a repeat CT scan showed a near-resolution of the abscesses. Eventually, the drains were removed and the patient was discharged home with a one-week course of levaquin and a 6-week course of Flagyl (Figure 1). Discussion: Hepatic amoebiasis is commonly seen in patients visiting from endemic areas such as India, Africa, Mexico and parts of Central/South America. Patients generally present with persistent right upper quadrant pain, fever, diaphoresis, malaise, hiccups, and weight loss. A serious complication of Amoebic liver abscess is rupture leading to peritonitis, or hepatic/IVC thrombosis. The antibiotic of choice is generally metronidazole, and large liver abscesses may require drainage. We document a case of large liver abscess requiring drain placement, and the successful utilization of a specially formulated tPA solution to effectively resolve the infection.Figure 1.: 4.5cm Liver abscess before administration of TPA, improved to 3.4cm following TPA.
2021-12-17 | ArfX2 GTPase Regulates Trafficking From the Trans-Golgi to Lysosomes and Is Necessary for Liver Abscess Formation in the Protozoan Parasite Entamoeba histolytica
Entamoeba histolytica is the causative agent of amoebic dysentery and liver abscess in humans. The parasitic lifestyle and the virulence of the protist require elaborate biological processes, including vesicular traffic and stress management against a variety of reactive oxygen and nitrogen species produced by the host immune response. Although the mechanisms for intracellular traffic of representative virulence factors have been investigated at molecular levels, it remains poorly understood whether and how intracellular traffic is involved in the defense against reactive oxygen and nitrogen species. Here, we demonstrate that EhArfX2, one of the Arf family of GTPases known to be involved in the regulation of vesicular traffic, was identified by comparative transcriptomic analysis of two isogenic strains: an animal-passaged highly virulent HM-1:IMSS Cl6 and in vitro maintained attenuated avirulent strain. EhArfX2 was identified as one of the most highly upregulated genes in the highly virulent strain. EhArfX2 was localized to small vesicle-like structures and largely colocalized with the marker for the trans-Golgi network SNARE, EhYkt6, but neither with the endoplasmic reticulum (ER)-resident chaperon, EhBip, nor the cis-Golgi SNARE, EhSed5, and Golgi-luminal galactosyl transferase, EhGalT. Expression of the dominant-active mutant form of EhArfX2 caused an increase in the number of lysosomes, while expression of the dominant-negative mutant led to a defect in lysosome formation and cysteine protease transport to lysosomes. Expression of the dominant-negative mutant in the virulent E. histolytica strain caused a reduction of the size of liver abscesses in a hamster model. This defect in liver abscess formation was likely at least partially attributed to reduced resistance to nitrosative, but not oxidative stress in vitro. These results showed that the EhArfX2-mediated traffic is necessary for the nitrosative stress response and virulence in the host.
cell therapies
2024-04-02 | Isolation and Potential Probiotic Characterization of Lactic Acid Bacteria from an Ethnic Fermented Beverage having Antibacterial Activity against Human Pathogen Entamoeba histolytica
Background Amoebiasis, caused by the human pathogen Entamoeba histolytica is one of the most common parasitic diseases. The existing anti-amoebic drugs show significant side effects in humans. Therefore, for effective control of this parasite, an alternative strategy is required. Microorganisms having probiotic potential are gaining global importance due to their health-promoting effects along with the safety aspects. Therefore, the present study aimed to isolate new lactic acid bacterial strains having anti-amoebic activity as well as probiotic potential from a traditional fermented beverage consumed by an Indian tribal community. Materials and Methods Twenty bacterial isolates have been selected based on their tolerance ability towards acid and bile salt. Their biofunctional aspects and anti-amoebic potential are studied. The most potential one was chosen through heatmap visualization and principal component analysis based on probiotic attributes. Finally, the opted isolate was studied for its in vivo safety evaluation using mouse model. Results and Discussion The isolates were found as Gram positive, catalase negative and able to ferment different carbohydrates. They showed significant killing activity against Entamoeba histolytica. They were found to have a high tolerance to gastrointestinal stresses, antioxidant activity, sensitivity to various antibiotics, high auto-aggregation activity (up to 28.78%), cell-surface hydrophobicity (up to 78.75%) and antibacterial activity. Their negative activity in gelatin hydrolysis and haemolysis assay indicates that they are safe. From 16s rDNA sequencing, they were found to be Limosilactobacillus sp. Among the isolates, B-51 was considered as the best probiotic strain by heatmap visualization and principal component analysis. Importantly, the strain B-51 showed beneficial effects in mice when supplemented through oral gavage. Conclusion The isolated strains from rice fermented beverage showed anti-amoebic activity along with interesting probiotic traits. The in vivo study findings of the best one proved its potential for therapeutic application in humans.
2011-02-25 | In vivo programmed cell death of Entamoeba histolytica trophozoites in a hamster model of amoebic liver abscess
Entamoeba histolytica trophozoites can induce host cell apoptosis, which correlates with the virulence of the parasite. This phenomenon has been seen during the resolution of an inflammatory response and the survival of the parasites. Other studies have shown that E. histolytica trophozoites undergo programmed cell death (PCD) in vitro, but how this process occurs within the mammalian host cell remains unclear. Here, we studied the PCD of E. histolytica trophozoites as part of an in vivo event related to the inflammatory reaction and the host-parasite interaction. Morphological study of amoebic liver abscesses showed only a few E. histolytica trophozoites with peroxidase-positive nuclei identified by terminal deoxynucleotidyltransferase enzyme-mediated dUTP nick end labelling (TUNEL). To better understand PCD following the interaction between amoebae and inflammatory cells, we designed a novel in vivo model using a dialysis bag containing E. histolytica trophozoites, which was surgically placed inside the peritoneal cavity of a hamster and left to interact with the host's exudate components. Amoebae collected from bags were then examined by TUNEL assay, fluorescence-activated cell sorting (FACS) and transmission electron microscopy. Nuclear condensation and DNA fragmentation of E. histolytica trophozoites were observed after exposure to peritoneal exudates, which were mainly composed of neutrophils and macrophages. Our results suggest that production of nitric oxide by inflammatory cells could be involved in PCD of trophozoites. In this modified in vivo system, PCD appears to play a prominent role in the host-parasite interaction and parasite cell death.
1992-11-01 | The destruction of virulent Entamoeba histolytica by activated human eosinophils.
Summary Unlike normal (i.e., non‐activated) human eosinophils that are unable to destroy virulent Entamoeba histolytica even in the presence of antibodies and complement, activated eosinophils effectively destroy the parasite in vitro without the help of opsonins, yet increase this capacity with their assistance. Many activated eosinophils succumb in the process as well, probably victims of toxic products released by dying amoebae. Human activated eosinophils thus behave more like activated macrophages than like neutrophil polymorphonuclear leucocytes that are notoriously incompetent in dealing with virulent amoebae. As a regular constituent of early inflammatory reactions, and notwithstanding the absence of blood and tissue eosinophilia in invasive amoebiasis, the activated eosinophil may play a role in the defence against E. histolytica .
oligonucleotides
2023-06-29 | Proteins differentially expressed between pathogenic and non-pathogenicEntamoeba histolyticaclones influence pathogenicity by different mechanisms
Abstract Recently, two genes involved in pathogenicity in a mouse model of amoebic liver abscess were identified based on their differential expression between non-pathogenic (A1 np ) and pathogenic (B2 p ) clones of the Entamoeba histolytica isolate HM:1-IMSS. While overexpression of a gene encoding the metallopeptidase EhMP8-2 decreases the virulence of the pathogenic clone B2 p , overexpression of the gene ehi_127670 ( ehhp127 ), encoding a hypothetical protein, increases the virulence of the non-pathogenic clone A1 np , while silencing this gene in B2 p decreases virulence. To understand the role of both molecules in determining the pathogenicity of E. histolytica , silencing and overexpression transfectants were characterized in detail. Silencing of ehmp8-2 , of the homologous gene ehmp8-1 , or of both together in A1 np trophozoites significantly altered the transcript levels of 60-350 genes. This strong change in the expression profile caused by the silencing of ehmp8-1 and/or ehmp8-2 implies that these peptidases regulate expression of numerous genes. Consequently, numerous phenotypic characteristics including cytopathic, hemolytic and cysteine peptidase activity were changed in response to their silencing. Silencing of ehhp127 in B2 p trophozoites did not affect other genes, whereas overexpression in A1 np trophozoites results in an altered expression of approximately 140 genes. EhHP127 appears to be important for trophozoite movement, as silencing negatively affects and overexpression positively affects trophozoite motility. Interestingly, the specific silencing of ehhp127 also impairs cytopathic activity, cysteine peptidase and hemolytic activity. All three molecules of interest, namely EhMP8-1, EhMP8-2, and EhHP127 can be detected in amoeba vesicles. Our results clearly show that the proteins studied here influence the pathogenicity of amoebae in different ways and use entirely different mechanisms to do so. Author summary The human pathogen Entamoeba histolytica can live asymptomatically in the intestine or become invasive and cause fatal liver abscesses. Approximately 15,000 people die each year as a result of an amoebic infection. Recently, two clones with different pathogenicity (A1 np : non-pathogenic; B2 p : pathogenic) derived from the E. histolytica isolate HM:1-IMSS were compared at the transcriptome level. Two highly differentially expressed genes ( ehhp127 encoding a hypothetical protein and ehmp8-2 encoding a metallopeptidase) were identified. Analysis of E. histolytica transfectants showed that silencing of ehhp127 and overexpression of ehmp8-2 in B2 p trophozoites reduced amoebic liver abscess formation in the mouse model. In this study, we characterized E. histolytica silencing and overexpression transfectants of ehmp8-2 , as well as of the homologous gene ehmp8-1 and of ehhp127 . It was shown that the altered expression of the metallopeptidase genes has a strong influence on the expression of a large number of genes and that the phenotype is strongly altered as a result. Silencing of ehhp127 does not affect the overall expression profile. However, specific silencing has a negative effect on motility, cysteine peptidase, hemolytic and cytopathic activity. All three molecules were shown to be localized in trophozoite vesicles.
2021-11-29 | Establishment of quantitative RNAi-based forward genetics in Entamoeba histolytica and identification of genes required for growth
While Entamoeba histolytica remains a globally important pathogen, it is dramatically understudied. The tractability of E . histolytica has historically been limited, which is largely due to challenging features of its genome. To enable forward genetics, we constructed and validated the first genome-wide E . histolytica RNAi knockdown mutant library. This library allows for Illumina deep sequencing analysis for quantitative identification of mutants that are enriched or depleted after selection. We developed a novel analysis pipeline to precisely define and quantify gene fragments. We used the library to perform the first RNAi screen in E . histolytica and identified slow growth (SG) mutants. Among genes targeted in SG mutants, many had annotated functions consistent with roles in cellular growth or metabolic pathways. Some targeted genes were annotated as hypothetical or lacked annotated domains, supporting the power of forward genetics in uncovering functional information that cannot be gleaned from databases. While the localization of neither of the proteins targeted in SG1 nor SG2 mutants could be predicted by sequence analysis, we showed experimentally that SG1 localized to the cytoplasm and cell surface, while SG2 localized to the cytoplasm. Overexpression of SG1 led to increased growth, while expression of a truncation mutant did not lead to increased growth, and thus aided in defining functional domains in this protein. Finally, in addition to establishing forward genetics, we uncovered new details of the unusual E . histolytica RNAi pathway. These studies dramatically improve the tractability of E . histolytica and open up the possibility of applying genetics to improve understanding of this important pathogen.
2018-08-31 | Trigger-induced RNAi gene silencing to identify pathogenicity factors of Entamoeba histolytica.
Recently, Entamoeba histolytica clones derived from isolate HM-1:IMSS that differ in their pathogenicity were identified. Whereas some clones induce amoebic liver abscesses (ALAs) in animal models of amoebiasis, others provoke only minimal liver lesions. Based on transcriptome studies of pathogenic and nonpathogenic clones, differentially expressed genes associated with reduced or increased liver pathology can be identified. Here, to analyze the influence of these genes on ALA formation in more detail, an RNA interference-trigger mediated silencing approach was used. Using newly identified trigger sequences, the expression of 15 genes was silenced. The respective transfectants were analyzed for their ability to induce liver destruction in the murine model for the disease. Silencing of EHI_180390 (encoding an AIG1 protein) increased liver pathology induced by a nonpathogenic parent clone, whereas silencing of EHI_127670 (encoding a hypothetical protein) decreased the pathogenicity of an initially pathogenic parent clone. Additional phenotypical in vitro analyses of EHI_127670 silencing as well as overexpression transfectants indicated that this molecule has an influence on size, growth, and cysteine peptidase activity of E. histolytica. This work describes an example of how the sole operational method for effective gene silencing in E. histolytica can be used for comprehensive analyses of putative pathogenicity factors.-Matthiesen, J., Lender, C., Haferkorn, A., Fehling, H., Meyer, M., Matthies, T., Tannich, E., Roeder, T., Lotter, H., Bruchhaus, I. Trigger-induced RNAi gene silencing to identify pathogenicity factors of Entamoeba histolytica.
2017-03-20 | Structural and functional studies of a noncanonical Dicer from Entamoeba histolytica
RNaseIII proteins are dsRNA-specific endonucleases involved in many important biological processes, such as small RNA processing and maturation in eukaryotes. Various small RNAs have been identified in a protozoan parasite Entamoeba histolytica. EhRNaseIII is the only RNaseIII endonuclease domain (RIIID)-containing protein in E. histolytica. Here, we present three crystal structures that reveal several unique structural features of EhRNaseIII, especially the interactions between the two helixes (α1 and α7) flanking the RIIID core domain. Structure and sequence analysis indicate that EhRNaseIII is a noncanonical Dicer and it lacks a dsRBD in the C-terminal region (CTR). In vitro studies suggest that EhRNaseIII prefers to bind and cleave longer dsRNAs, generating products around 25 nucleotides in length. Truncation of the CTR or attaching the dsRBD of Aquifex aeolicus RNaseIII can enhance the binding and cleavage activities of EhRNaseIII. In combination with in vitro crosslinking assay, our results suggested that EhRNaseIII functions in a cooperative mode. We speculate that some partner proteins may exist in E. histolytica and regulates the activity of EhRNaseIII through interaction with its CTR. Our studies support that EhRNaseIII plays an important role in producing small RNAs in E. histolytica.
2016-12-21 | EhNPC1 and EhNPC2 Proteins Participate in Trafficking of Exogenous Cholesterol in Entamoeba histolytica Trophozoites: Relevance for Phagocytosis
Entamoeba histolytica, the highly phagocytic protozoan causative of human amoebiasis lacks the machinery to synthesize cholesterol. Here, we investigated the presence of NPC1 and NPC2 proteins in this parasite, which are involved in cholesterol trafficking in mammals. Bioinformatics analysis revealed one Ehnpc1 and two Ehnpc2 genes. EhNPC1 appeared as a transmembrane protein and both EhNPC2 as peripheral membrane proteins. Molecular docking predicted that EhNPC1 and EhNPC2 bind cholesterol and interact with each other. Genes and proteins were identified in trophozoites. Serum pulse-chase and confocal microscopy assays unveiled that after trophozoites sensed the cholesterol source, EhNPC1 and EhNPC2 were organized around the plasma membrane in a punctuated pattern. Vesicles emerged and increased in number and size and some appeared full of cholesterol with EhNPC1 or EhNPC2 facing the extracellular space. Both proteins, but mostly EhNPC2, were found out of the cell associated with cholesterol. EhNPC1 and cholesterol formed networks from the plasma membrane to the nucleus. EhNPC2 appeared in erythrocytes that were being ingested by trophozoites, co-localizing with cholesterol of erythrocytes, whereas EhNPC1 surrounded the phagocytic cup. EhNPC1 and EhNPC2 co-localized with EhSERCA in the endoplasmic reticulum and with lysobisphosphatidic acid and EhADH (an Alix protein) in phagolysosomes. Immunoprecipitation assays confirmed the EhNPC1 and EhNPC2 association with cholesterol, EhRab7A and EhADH. Serum starved and blockage of cholesterol trafficking caused a low rate of phagocytosis and incapability of trophozoites to produce damage in the mouse colon. Ehnpc1 and Ehnpc2 knockdown provoked in trophozoites a lower intracellular cholesterol concentration and a diminished rate of phagocytosis; and Ehnpc1 silencing also produced a decrease of trophozoites movement. Trafficking of EhNPC1 and EhNPC2 during cholesterol uptake and phagocytosis as well as their association with molecules involved in endocytosis strongly suggest that these proteins play a key role in cholesterol uptake.
small molecules
2026-08-20 | A review into the recent advances in the world of amoebiasis
PURPOSE OF REVIEW: Amoebiasis is a parasitic infection caused by Entamoeba histolytica , affecting 10% of the global population. It is a well recognized cause of morbidity and mortality in low-middle-income countries where it is endemic. However, with increased migration and global travel, amoebiasis is now more common in high-income countries, although diagnosis is often delayed or even missed due to lack of awareness of the latest epidemiology and optimal diagnostic testing. This review discusses the evolving prevalence, and the current international guidelines for the investigation and treatment of amoebiasis, focusing on recent advances. RECENT FINDINGS: The recent literature shows that the primary investigations for amoebiasis remain the same, though newer modalities such as artificial intelligence-powered microscopy and metagenomics have been developed recently, which aids the accuracy and speed of diagnosis. Treatment remains the same, though current research has found potential new drugs and drug targets which show promise. SUMMARY: This review reinforces the importance of early clinical suspicion, diagnosis and treatment for amoebiasis. What was once a disease only seen in endemic countries or travel-associated imported cases is now more common and must not be missed.
2026-08-02 | In vitro antiamoebic activity of novel metronidazole derivatives and silver nanoparticle formulations against clinical isolates of Entamoeba histolytica
Amoebiasis from Entamoeba histolytica continues to be a significant global health problem, and treatment with metronidazole is limited due to adverse effects and loss of efficacy. The objectives of this study were to design, synthesise and evaluate novel metronidazole derivatives along with their respective silver nanoparticle AgNP formulations as potential anti-amoebic agents. Molecular docking in silico against E. histolytica thioredoxin reductase (EhTrxR) was employed to develop five derivatives (E1, E2, E4, E7 and E10), which were synthesized and then structurally confirmed by mass spectrometry (MS) and ¹H nuclear magnetic resonance (¹H NMR). Silver nanoparticles were synthesised by the green method and characterised through UV-Vis, FTIR, XRD and FESEM, indicating spherical particles with sizes between 29.54 and 53.48 nm. In the docking results, among the tested derivatives, E1 showed the strongest predicated binding affinity against EhTrxR, with an energy score of − 10.40 kcal/mol, followed by E7 and E10. The binding affinity of E1 was also notably stronger than that of E2 and E4, indicating its more favourable based interaction with target enzyme. The derivatives exhibited a very effective anti-amoebic activity in vitro, particularly when combined with AgNPs. At 48 h, the highest trophozoite mortality (90%) was observed for E10 + AgNPs, followed by E7 + AgNPs (73%), in comparison to metronidazole alone which demonstrated only 30% and increased up to 55% when combined with AgNPs. In cyst assays E1 had the most activity, with mortality up to 75% at 40 min compared with 50% for metronidazole. All treatments exhibited significant dose- and time-dependent effects ( p < 0.001). Both novel metronidazole derivatives and the metronidazole-AgNPs formulations exhibit increased anti-amoebic activity over their corresponding compounds alone, particularly E1 and its AgNPs formulations results which could be a first step towards the identification of anti-amoebic leads but still no therapeutic implications can be drawn without carrying out mechanism studies, toxicity studies, selectivity assays and in vivo evaluation.
2026-06-19 | Gastrointestinal disorders due to parasites – a narrative review of the literature
Intestinal parasites constitute a significant public health problem, particularly in developing countries. It is estimated that over 1.5 bln people worldwide are infected with intestinal parasites. These pathogens fall into 2 main groups: protozoa (e.g., Giardia duodenalis, Entamoeba histolytica, Cryptosporidium) and helminths – multicellular worms, which include roundworms (e.g., roundworm, pinworm, hookworm), tapeworms (Taenia spp., Diphyllobothrium latum), and flukes (Schistosoma spp.).Parasites cause illnesses with diverse clinical presentations, ranging from asymptomatic carriage to acute and chronic diarrhea, abdominal pain, malnutrition, and anemia. Some, such as E. histolytica, lead to invasive amoebiasis, while T. solium leads to neurocysticercosis, which contributes to epilepsy. Others, such as Giardia, disrupt intestinal absorption, leading to wasting, especially in children.Diagnosis is primarily based on stool examination (microscopy, antigen testing, PCR). Treatment depends on the parasite – metronidazole, albendazole, praziquantel, and ivermectin are used, among others. Increasing attention is being paid to supporting treatment with probiotics and zinc supplementation, which improve therapeutic outcomes, especially in protozoal infections.The pathogenesis of infections includes mechanical intestinal damage, bleeding, nutrient utilization by parasites, and the induction of inflammatory responses and microbiome dysbiosis. Parasites lead to serious health consequences, particularly in children (deficiencies, impaired growth and development).Prevention relies on improved sanitation, access to clean water, health education, cooking meat, mass deworming in endemic areas, and basic personal hygiene. Effective vaccines do not exist, although research is ongoing.
2026-02-28 | The Impact of Medicinal Plant Extracts on Entamoeba histolytica Parasite in Rats: A Study on Hematological and Biochemical Parameters
Background: Entamoeba histolytica poses a global health threat, especially in regions of the world where sanitation is deficient, due to its potential to cause amoebiasis. It leads to gastrointestinal diseases, including dysentery, colitis and liver abscesses, with about 50 million cases and 100,000 deaths annually. Medicinal plants containing a variety of bioactive compounds have shown significant potential as therapeutic intervention for parasitic infections and these remedies are also reported to be associated with less side effects, lower supplementary cost compared to the synthetic drugs. Natural herbs including Azadirachta indica (neem), Allium sativum (garlic), and Curcuma longa (turmeric) showed antiparasitic, anti-inflammatory, and antimicrobial activity which are potential alternatives to synthetic drugs. Objectives: The present study was aimed at exploring the effects of extracts from neem, garlic and turmeric on E. histolytica infection in rats This involved analyzing alterations in hematological (blood-related) and biochemical markers to evaluate the therapeutic efficacy of these plant extracts against the infection. Methods: The following experimental design was used which consisted of three groups of Wistar rats: Control group – Healthy and no infection or treatment. Infected group – E. histolytica infected rats without treatment. Treatment group – Infected rats treated with medicinal plant extracts The plant parts, that is leaves of neem, bulbs of garlic and rhizomes of turmeric were dried and grounded followed by extraction with ethanol. The treatment group was administered orally extracts for 14 days post 24 h of the infection of E. histolytica). Whole blood was collected at baseline and on days 7 and 14, for hematological and biochemical analysis. The study evaluated red and white blood cell counts, hemoglobin, hematocrit levels, liver enzymes, kidney function indicators and electrolyte balance. Results: The infected rats presented with a lower in red blood cell be counted, hemoglobin and hematocrit showed anemia, the remedy group confirmed partial recovery of those values. White blood cell counts had been elevated in tainted rats due to the resistance response, number those levels went down inside the treatment relationship, demonstrating diminished aggravation. Liver enzymes (ALT and AST) had higher significantly in infected rats showing liver injury. The treatment group had a significant decrease of these enzymes, indicating a hepatoprotective effect. In infected rats, markers of kidney characteristics (creatinine and urea) have been multiplied showing a state of renal dysfunction. Plant extracts improved those markers, suggesting the safety of the kidneys. In the remedy organization, some electrolyte imbalances (lower sodium in blood and potassium, altered chloride) notwithstanding yet found in enraged rats have been righted. The sensitivity and specificity of diagnostic check for detecting E. Histolytica contamination had been extreme in each infected and treatment teams demonstrating that plant extracts did not intrude considerably with the accuracy of the diagnostics. Conclusion: The study demonstrated that medicinal extracts of Neem, Garlic and Turmeric can have very significant therapeutic effects on E. Histolytica infected rats (p<0.0001). The amelioration of hematological and biochemical parameters demonstrated the pharmacological potential of these plants to treat amoebiasis as alternative medicine. These therapeutic effects were attributed to the anti-inflammatory, antimicrobial and antioxidants properties of the composite plant. These findings were remarkable and should be studied further to optimize the application of these plants in pharmaceutical formulations for amoebiasis treatment, especially in areas where access to conventional drugs is limited.
2025-08-20 | Cryo-EM structure of ribosome from pathogenic protozoa Entamoeba histolytica reveals unique features of its architecture
Entamoeba histolytica, an anaerobic protozoan parasite, is the causative agent of amoebiasis, bloody diarrhea, and liver abscesses in humans. Amoebiasis is more predominant in tropical areas with poor sanitation conditions, and it remains the fourth leading cause of death due to a protozoan infection. E. histolytica life cycle spans between an infective 'cyst stage' and an active disease-causing 'trophozoite stage'. We have isolated ribosomes from the trophozoite stage of E. histolytica. Here, we report single particle cryo-EM structures of the 53S ribosome large subunit (LSU), and 75S associated ribosomes, with P-tRNA, A/P and P/E tRNAs, and with paromomycin antibiotic, at 2.8 Å to 3.4 Å resolution. The E. histolytica possesses a reduced ribosome with a conserved core, and the periphery evolved with species-specific unique features. The most notable features are the presence of the rRNA triple helix near the peptide exit tunnel, the expansion segment H88ES102 near the exit site on LSU, and unique insertions in r-proteins. Furthermore, the 75S ribosome paromomycin complex structure provides the atomic details of its interactions. These structures provide insights into the evolutionary adaptation of the E. histolytica translational machinery and may be explored further for amoebicidal therapeutic intervention.
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2026-06-09 | CRISPR/Cas9 knockout and editing of the major cysteine protease in Entamoeba histolytica
Entamoeba histolytica is the cause of amoebiasis, a diarrheal infection that is a significant source of morbidity and mortality. Despite its importance to human health, the basic mechanism of disease is poorly understood. E. histolytica is dramatically understudied, even in comparison to other understudied parasites, due to challenging features of its genome and the relative paucity of genetic tools. A major limitation is the historical lack of gene knockouts or manipulation of the endogenous genome. While CRISPR/Cas9 has led to major advances in the tractability of numerous parasites, until recently, it was not applied in E. histolytica, except for the demonstration of editing of an episomal plasmid. In this study, we further developed CRISPR/Cas9 and demonstrated the successful targeting of the endogenous cysteine protease 5 (CP5) gene, a major virulence factor. Further, we demonstrated successful CRISPR/Cas9-based editing of this locus, which represents the very first successful editing of the endogenous genome. In the course of these approaches, we developed the viral skip peptide approach as well as a suite of endogenous promoters to drive tunable levels of gene expression. We also performed the most extensive empirical testing of nuclear localization signals in E. histolytica that has been done. Thus, this work demonstrates effective CRISPR/Cas9-based manipulation of the endogenous genome, together with significant advances to the overall genetic toolkit that extend beyond CRISPR/Cas9. These great improvements in the tractability of E. histolytica thus set the stage for future studies to better define its virulence.
2007-06-06 | Replacement of the essential Dictyostelium Arp2 gene by its Entamoeba homologue using parasexual genetics
Cell motility is an essential feature of the pathogenesis and morbidity of amoebiasis caused by Entamoeba histolytica. As motility depends on cytoskeletal organisation and regulation, a study of the molecular components involved is key to a better understanding of amoebic pathogenesis. However, little is known about the physiological roles, interactions and regulation of the proteins of the Entamoeba cytoskeleton.We have established a genetic strategy that uses parasexual genetics to allow essential Dictyostelium discoideum genes to be manipulated and replaced with modified or tagged homologues. Our results show that actin related protein 2 (Arp2) is essential for survival, but that the Dictyostelium protein can be complemented by E. histolytica Arp2, despite the presence of an insertion of 16 amino acids in an otherwise highly conserved protein. Replacement of endogenous Arp2 with myc-tagged Entamoeba or Dictyostelium Arp2 has no obvious effects on growth and the protein incorporates effectively into the Arp2/3 complex.We have established an effective two-step method for replacing genes that are required for survival. Our protocol will allow such genes to be studied far more easily, and also allows an unambiguous demonstration that particular genes are truly essential. In addition, cells in which the Dictyostelium Arp2 has been replaced by the Entamoeba protein are potential targets for drug screens.
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Drug Discovery Landscape
5 orphan drug designations for Amoebiasis due to Entamoeba histolytica, including 1 approved therapy.
5 orphan drug designations for Amoebiasis due to Entamoeba histolytica, including 1 approved therapy.
Drug | Therapy type | Orphan designation | Clinical trial status | Sponsor |
|---|---|---|---|---|
miltefosine | small molecules | FDA | — | Profounda, Inc. |
auranofin | small molecules | FDA | Ctr for Discovery & Innovation in Parasitic Diseas | |
Geneticin | small molecules | FDA | — | ProcesScience, Inc. (PSI) |
Tinidazole [Tindamax] | small molecules | FDA | Approved | Presutti Laboratories, Inc. |
nitazoxanide | small molecules | FDA | Romark Laboratories, L.C. |
“Terminated” – programs with discontinued clinical trials, or with no updates reported for 5 years after completion or 12 years after the last trial started.
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