Evolutionary genomics and population structure of Entamoeba histolytica

Abstract

Amoebiasis caused by the gastrointestinal parasite Entamoeba histolytica has diverse disease outcomes. Study of genome and evolution of this fascinating parasite will help us to understand the basis of its virulence and explain why, when and how it causes diseases. In this review, we have summarized current knowledge regarding evolutionary genomics of E. histolytica and discussed their association with parasite phenotypes and its differential pathogenic behavior. How genetic diversity reveals parasite population structure has also been discussed. Queries concerning their evolution and population structure which were required to be addressed have also been highlighted. This significantly large amount of genomic data will improve our knowledge about this pathogenic species of Entamoeba.

Keywords: Disease outcome; Genetic polymorphism; Genetic recombination; Genotyping; Short tandem repeat loci; Single nucleotide polymorphism.

Fig. 1

E. histolytica isolates remaining asymptomatic are genetically closer to those causing liver abscess: depicted by (A) phylogenetic tree, (B) graphical representation. Phylogeny was based on tRNA linked N-K2 (STR) locus. The sequences of all (a total of 22) representative STR patterns from N-K2 locus, obtained from the genetic analysis of 51 study isolates were aligned using ClustalW multiple alignment program of MEGA Version 4 software. Phylogenetic tree was constructed from the alignment through “Generalized Time Reversal (GTR) + gamma” substitution model of SeaView Graphical Interface Version 4 software using a maximum likelihood matrix algorithm. One distinct “D” group, one distinct “LA” group and one mixed “AS + LA” group can be assigned. ‘D’ group contains STR patterns found exclusively in diarrheal outcome. ‘LA’ group contains STR patterns found only in liver abscess outcome. ‘AS + LA’ group contains STR patterns exclusive for asymptomatic (AS) and liver abscess (LA) outcome.