Abstract
For over 30 years it has been established that the Entamoeba histolytica protozoan included two biologically and genetically different species, one with a pathogenic phenotype called E. histolytica and the other with a non-pathogenic phenotype called Entamoeba dispar. Both of these amoebae species can infect humans. E. histolytica has been considered as a potential pathogen that can cause serious damage to the large intestine (colitis, dysentery) and other extraintestinal organs, mainly the liver (amebic liver abscess), whereas E. dispar is a species that interacts with humans in a commensal relationship, causing no symptoms or any tissue damage. This paradigm, however, should be reconsidered or re-evaluated. In the present work, we report the detection and genotyping of E. dispar sequences of DNA obtained from patients with amebic liver abscesses, including the genotyping of an isolate obtained from a Brazilian patient with a clinical diagnosis of intestinal amebiasis that was previously characterized as an E. dispar species. The genetic diversity and phylogenetic analysis performed by our group has shown the existence of several different genotypes of E. dispar that can be associated to, or be potentiality responsible for intestinal or liver tissue damage, similar to that observed with E. histolytica.
Highlights
Entamoeba histolytica is the etiological agent of human amebiasis
Extraction and PCR amplification of polymorphic regions of non-transcribed intergenic regions associated with tRNA genes using both E. histolytica and E. dispar specific primers
We made four different groups for diversity genetics analysis: sequences of E. dispar obtained from liver abscesses analyzed in the present study, all sequences of the species E. dispar available in GenBank data base, sequences of E. histolytica obtained from liver abscesses in this study and the total sample of sequences from E. histolytica accessed in GenBank
Summary
Entamoeba histolytica is the etiological agent of human amebiasis. The most common clinical forms of disease are amebic colitis and amebic liver abscess. Recent studies on the genetic diversity in both the E. histolytica and E. dispar species, detected in infected individuals presenting with different outcomes of the infection (i.e., asymptomatic or invasive disease), has unveiled the extraordinary polymorphism of both Entamoeba species [8,9,10,11,12]. These studies analyzed the coding and non-coding DNA regions of these species, allowing a better understanding of the heterogeneous character of the parasite infection sources as well as the complexity of the human. The phylogenetic relations of the DNA sequences obtained in our study are discussed
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