Entamoeba histolytica Cytotoxin: Purification, Characterization, Strain Virulence, and Protease Activity

McGowan, Katherine; Deneke, Carl F.; Thorne, Grace M.; Gorbach, Sherwood L.

doi:10.1093/infdis/146.5.616

Cited by 53 publications

(18 citation statements)

References 30 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In contrast to the marked inhibitory effect on the phagocytosis induced by HM1:IMSS toxin, the toxin of the less virulent strain NIH:200 did not produce a significant inhibitory effect on the activity of PMNs. This is in agreement with the report by McGowan et al [12] who demonstrated that strain HM1:IMSS possessed marked cytotoxic activity on PMNs while strain NIH:200 exhibited a moderate activity.…”

Section: Discussionsupporting

confidence: 93%

See 1 more Smart Citation

Effect ofEntamoeba HistolyticaToxins on Isolated Human Polymorphonuclear Leukocytes' Phagocytic Function

Al-Tuwaijri

1992

Ann Saudi Med

View full text Add to dashboard Cite

This study was undertaken to investigate the effect of Entamoeba histolytica toxin (Ehp/t) obtained from HM1:IMSS strain on human polymorphonuclear leukocytes (PMNs) phagocytic function. A less virulent strain, i.e., NIH:200 was also used in this study for comparison. The results revealed that the toxin obtained from the strain HM1:IMSS inhibited the phagocytic activity of PMNs as measured by yeast uptake or chemiluminescence response while the toxin of strain NIH:200 did not show any significant effect. On the other hand, washing of PMNs that had been pre-exposed to the toxin of strain HM1:IMSS failed to reverse the effect of the toxin on PMNs. Heat inactivation of the toxin failed to alter its effect on PMNs. Addition of N-acetyl-D-galactosamine (GalNAc) to the PMNs did not alter the activity of Ehp/t toxin. These findings suggested that Ehp/t toxin might induce similar effect on PMNs of patients infected with ameba. ' Phagocytic Function. 1992; 12(4): 372-376 Entamoeba histolytica is a protozoan parasite of the large intestine of man which has a worldwide distribution. About 10% of the world population is estimated to be infected with the parasite [1]. This infection is mostly associated in communities where the standard of sanitation is poor [2]. A relatively high proportion of infected people usually develop amebiasis which is a type of disease resulting from the invasion of the parasite to the large intestine of the host. AS Al-Tuwaijri, Effect of Entamoeba Histolytica Toxins on Isolated Human Polymorphonuclear LeukocytesAlthough several studies have been performed in an attempt to understand the host-parasite interaction in amebic infection, the exact mechanism of tissue damage is not as yet fully understood [3]. Both the toxin of the ameba parasite and host factors such as polymorphonuclear leukocytes (PMNs) have been implicated in the early events of the invasion by the ameba parasites [4,5]. The oxygen-free radicals released from PMNs upon stimulation may play a vital role in the severity of the tissue damage and in cecal tissue invasion in experimental amebic colitis [6].Results obtained in this laboratory have shown that E. histolytica toxin (Ehp/t) depresses the luminol-dependent chemiluminescence responses of human PMNs in vitro [7]. Conversely, Salata and Ravdin [3] reported that the destruction of liver cell monolayers by E. histolytica was enhanced by lysed PMNs. These authors suggested that the tissue damage was not likely to be mediated by oxygen-free radicals released from stimulated PMNs. To further shed some light on the possible mechanisms of the pathogenesis of amebiasis, the present study was undertaken to examine the effect of a toxin obtained from a virulent strain of E. histolytica, i.e, HM1:IMSS, on the phagocytic activity of human PMNs. The luminol-dependent chemiluminescence (CL) responses and opsonized yeast uptake were utilized to assess the effect of Ehp/t toxins on phagocytosis. A less virulent strain NIH:200 was included in the study for comparison.

show abstract

Section: Discussionsupporting

confidence: 93%

“…histolytica toxin (Ehp/t) was obtained from the virulent strain HM1:IMSS was kindly provided by Dr. Pittman (USA). Toxin of strain NIH:200 was prepared from axenic trophozoites as described by McGowan et al [12].…”

Section: Entamoeba Histolytica Toxinmentioning

confidence: 99%

Effect ofEntamoeba HistolyticaToxins on Isolated Human Polymorphonuclear Leukocytes' Phagocytic Function

Al-Tuwaijri

1992

Ann Saudi Med

View full text Add to dashboard Cite

show abstract

“…The analysis revealed that we could successfully differentiate the genotypes of E. histolytica and E. dispar. Additionally, strain EH (Rahman), a less virulent strain as assessed by decreased monolayer destruction, disease in animal models, cytotoxicity, and the only EH strain isolated from an asymptomatic individual was the most divergent of the EH strains and clustered separately from the virulent EH strains with significant bootstrap values (13,27,(48)(49)(50)(51). The separation of the EH (Rahman) strain from the other EH strains could also reflect the geographic origins of the strains and be unrelated to parasite phenotypes.…”

Section: Vol 4 2005 Genotypes Of Entamoeba Correlate With Virulencementioning

confidence: 99%

Comparative Genomic Hybridizations ofEntamoebaStrains Reveal Unique Genetic Fingerprints That Correlate with Virulence

et al. 2005

View full text Add to dashboard Cite

Variable phenotypes have been identified for Entamoeba species. Entamoeba histolytica is invasive and causes colitis and liver abscesses but only in ϳ10% of infected individuals; 90% remain asymptomatically colonized. Entamoeba dispar, a closely related species, is avirulent. To determine the extent of genetic diversity among Entamoeba isolates and potential genotype-phenotype correlations, we have developed an E. histolytica genomic DNA microarray and used it to genotype strains of E. histolytica and E. dispar. On the basis of the identification of divergent genetic loci, all strains had unique genetic fingerprints. Comparison of divergent genetic regions allowed us to distinguish between E. histolytica and E. dispar, identify novel genetic regions usable for strain and species typing, and identify a number of genes restricted to virulent strains. Among the four E. histolytica strains, a strain with attenuated virulence was the most divergent and phylogenetically distinct strain, raising the intriguing possibility that genetic subtypes of E. histolytica may be partially responsible for the observed variability in clinical outcomes. This microarray-based genotyping assay can readily be applied to the study of E. histolytica clinical isolates to determine genetic diversity and potential genotypic-phenotypic associations.Entamoeba histolytica causes amebic colitis and liver abscesses. Worldwide, 50 million people have invasive E. histolytica, and 100,000 die each year, making it the second most common cause of parasitic death in humans (71). In Dhaka, Bangladesh, where diarrheal diseases are the leading cause of death in children less than 6 years old, ϳ50% of children have serological evidence of exposure to E. histolytica by age 5 (34, 35). Infected children suffer from significant morbidity with malnourishment and growth delays. A number of interesting epidemiologic trends have been identified for amebic disease. The data, although limited, indicate that a minority (ϳ10%) of individuals who become infected with E. histolytica progress to clinically overt disease; others remain asymptomatically colonized (29). In individuals with invasive disease, occurrence of amebic liver abscess (ALA) is 5 to 50 times less common than diarrhea (65). Geographically variable disease predilections have been observed, and invasive disease predominantly affects men (1, 2, 11, 61).The extent of genetic diversity among E. histolytica clinical isolates is unclear. Studies have analyzed a small number of highly repetitive and polymorphic genetic loci by techniques, such as randomly amplified polymorphic DNA (RAPD), RNA arbitrarily primed PCR, and restriction fragment length polymorphism (RFLP), to conclude that there is significant genetic diversity (7,18,23,31,33,64,72,73). Contradictory data were obtained by two studies; in one study, the lectin gene was sequenced, and in the other study, the intergenic region between the superoxide dismutase gene and the actin 3 gene was analyzed (9, 30). These studies found minimal genetic diversi...

show abstract

“…Interstrain variations in the adhesion of E. histolytica trophozoites to human epithelium have been demonstrated for two E. histolytica strains (1,10), in which underrepresentation of the 35-kDa light subunit of the Gal-GalNAc lectin in the avirulent Rahman strain was shown to be correlated with a lack of cytopathic activity (1). Variations in cysteine proteinase expression between highly virulent and avirulent strains were also reported (23). In addition, marked differences in the levels of lipophosphoglycan-like and lipophosphopeptidoglycan molecules were demonstrated between virulent and avirulent strains of E. histolytica (24).…”

mentioning

confidence: 93%

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

et al. 2003

View full text Add to dashboard Cite

It has been known that only 5 to 10% of those infected with Entamoeba histolytica develop symptomatic disease. However, the parasite and the host factors that determine the onset of disease remain undetermined. Molecular typing by using polymorphic genetic loci has been proven to aid in the close examination of the population structure of E. histolytica field isolates in nature. In the present study, we analyzed the genetic polymorphisms of two noncoding loci (locus 1-2 and locus 5-6) and two protein-coding loci (chitinase and serine-rich E. histolytica protein [SREHP]) among 79 isolates obtained from different geographic regions, mainly Japan, Thailand, and Bangladesh. When the genotypes of the four loci were combined for all isolates that we have analyzed so far (overlapping isolates from mass infection events were excluded), a total of 53 different genotypes were observed among 63 isolates. The most remarkable and extensive variations among the four loci was found in the SREHP locus; i.e., 34 different genotypes were observed among 52 isolates. These results demonstrate that E. histolytica has an extremely complex genetic structure independent of geographic location. Our results also show that, despite the proposed transmission of other sexually transmitted diseases, including human immunodeficiency virus infection, from Thailand to Japan, the spectra of the genotypes of the E. histolytica isolates from these two countries are distinct, suggesting that the major E. histolytica strains prevalent in Japan at present were likely introduced from countries other than Thailand. Although the genetic polymorphism of the SREHP locus was previously suggested to be closely associated with the clinical presentation, e.g., colitis or dysentery and liver abscess, no association between the clinical presentation and the SREHP genotype at either the nucleotide or the predicted amino acid level was demonstrated.

show abstract

Entamoeba histolytica Cytotoxin: Purification, Characterization, Strain Virulence, and Protease Activity

Cited by 53 publications

References 30 publications

Effect ofEntamoeba HistolyticaToxins on Isolated Human Polymorphonuclear Leukocytes' Phagocytic Function

Effect ofEntamoeba HistolyticaToxins on Isolated Human Polymorphonuclear Leukocytes' Phagocytic Function

Comparative Genomic Hybridizations ofEntamoebaStrains Reveal Unique Genetic Fingerprints That Correlate with Virulence

Geographic Diversity among Genotypes of Entamoeba histolytica Field Isolates

Contact Info

Product

Resources

About