Genetic diversity inEntamoeba histolytica

Entamoeba dispar strains: analysis of polymorphism in Tunisian isolates

The ability to detect intra-species polymorphism in Entamoeba histolytica and Entamoeba dispar is an important tool for studying geographic distribution and transmission mechanisms. E. dispar and E. histolytica share the same mechanism for transmission among human hosts, and so after differentiation between these species. We studied the intra-species variation and distribution of E. dispar strains obtained from cyst passers, specifically from African students and Tunisian food handlers. We analyzed the polymorphic region of the chitinase protein gene in 13 individuals infected with E. dispar, of which 9 were from Tunisia and 4 from other African countries. We identified 7 different chitinase patterns in Tunisians while the 4 isolates from other countries each had a distinct pattern. Two of the patterns we found have been reported in studies from Mexico and India, possibly indicating worldwide spread of certain strains.

High genetic diversity among Iranian Entamoeba dispar isolates based on the noncoding short tandem repeat locus D-A

This study has identified and characterized the structure of locus D-A, a noncoding short tandem repeat (STR) region, also known as locus 1-2, in Iranian Entamoeba dispar isolates. This polymorphic locus has been shown to be potentially useful in investigating the molecular epidemiology of Entamoeba histolytica and E. dispar. The genetic polymorphisms in locus D-A in 28 isolates of E. dispar from three different geographic regions of Iran were distinguished using PCR and sequencing, and the results were compared with the E. dispar gene sequences available in GenBank. In all microscopy-positive E. histolytica/E. dispar samples, PCR with species-specific primers was used to amplify a 477-531 bp product, identifying the samples that had E. dispar. Analysis of the sequences revealed a remarkable degree of genetic diversity with regard to size, number and organization of the repeat units among the E. dispar isolates. The sequenced products showed 12 novel E. dispar genotypes, which have been submitted to the GenBank/EMBL/DDBJ database under accession numbers AB354125-AB354136.