Genetic Characterization of Echinococcus granulosus Strain Causing for Cystic Echinococcosis in Human

Abstract Background: Cystic echinococcosis is caused by the larval stage of Echinococcus granulosus . Humans become infected by ingestion of parasite eggs with contaminated water and food or by direct contact with definitive hosts. Molecular studies have identified 10 genotypes (G1–G10) within E. granulosus . Objectives: The current study is conducted to determine genotypes (strains) of E . granulosus that cause cystic echinococcosis in humans in Thi-Qar province, Iraq, using polymerase chain reaction (PCR) technique and sequence analysis of the mt 12S rRNA gene. Materials and Methods: The molecular study was conducted on 15 hydatid cysts isolated from 15 patients with cystic echinococcosis who underwent surgical operations at the Imam Hussein Teaching Hospital, located in the center of the Al-Nasiriyah city, Thi-Qar province, Iraq, using PCR technique and sequencing of the mt 12S rRNA gene. Results: The PCR technique was utilized for amplifying a single fragment of 254 bp length of the mt 12S rRNA gene in all hydatid cysts. Sequence analysis of mt 12S rRNA gene showed the presence of E . granulosus genotype G1 (Sheep strain) in human hydatid cysts when compared with selected sequences in the present study with the reference sequences of E . granulosus genotype G1 in GenBank database. In addition, five sequences in the present study were registered in GenBank database for the first time under accession numbers (LC712863, LC712864, LC712865, LC712866, and LC712867). Genetic variation within genotype G1 (the G1 variant G163T) was observed in a hydatid cyst sample isolated from the human kidney with accession number LC712863.1. Conclusion: The current results concluded that the E. granulosus genotype G1 is responsible for human cystic echinococcosis in Thi-Qar province.