Chitinase-gene-based analysis of the genetic variability among the clinical isolates of Entamoeba dispar from Puducherry, India

INTRODUCTION: Amebiasis is known to be caused by the protozoan parasite Entamoeba histolytica. Entamoeba dispar is considered to be a sibling species of E. histolytica, as the two are phylogenetically closest. There are reports that certain strains of E. dispar isolated were capable of causing hepatic lesions in the experimental animal models. The intra-/inter-species genetic variation has been found to have profound implication in the invasiveness of the disease. Thus, studying polymorphism in E. dispar aids to improve our perspective related to the variability in the genome of the parasite. MATERIALS AND METHODS: The highly polymorphic region of the gene encoding the enzyme chitinase was targeted for the strain variation analysis in E. dispar. Isolates from the stool and liver abscess aspirate were subjected to the polymerase chain reaction (PCR) for the amplification of the targeted polymorphic loci. The PCR products were sequenced, and genetic variability analysis was carried out. RESULTS: A total of 23 samples in the stool and 1 sample from liver abscess pus were positive for E. dispar by nested multiplex PCR which was confirmed by sequencing. Of these positive samples, 13 amplified for chitinase gene by PCR. We observed seven genotypes in our study isolates, of which four were found to be distinct. CONCLUSION: This study shows that high degree of genetic variation exists among the clinical isolates of E. dispar in our location. The future studies including the analysis of other genetic makers such as serine-rich E. dispar protein or other loci have to be carried out to get an idea about the distribution of the different strains of E. dispar.