Molecular Differentiation of Fasciola Species and Characteriza¬tion of Genetic Diversity of F. gigantica Using NADH Dehy¬drogenase I (ND1) Gene in the Endemic Areas of Iran

Fasciola hepatica and F. gigantica are the causative agents of fasciolosis in domestic animals and humans. Based on the morphometric criteria, differential diagnosis between them is problematic. In addition, intermediate forms of Fasciola have been found in Iran, which makes the differentiation more difficult. The aim of the present study was to provide molecular evidence for the existence of F. gigantica in Iran using sequencing analysis of ND1 and PCR-RFLP analysis of ITS2 regions and to study the intraspecies variations of F. gigantica based on mitochondrial ND1 gene polymorphism. Forty Fasciola spp. samples collected from four distinct provinces (Fars, Khuzestan, Gilan, Khorasan Razavi) in Iran were collected for morphological and molecular characterization. In molecular method, PCR-RFLP analysis of ITS2 us­ing pagI restriction enzyme was used as a screening approach for F. gigantica differentia­tion. Then mitochondrial DNA sequence variations in the ND1 gene were used for phylogenetic analysis. Based on the morphometric criteria and RFLP analysis, 14 parasitic sam­ples were initially identified to be F. gigantica. Phylogenetic results showed that there are at least 10 different genotypes of F. gigantica in Iran, which are different from those existing in the GenBank. Twenty-six points out of 410 base pairs of se­quenced ND1 gene in 10 varieties of F. gigantica were diagnosed to be polymorphic. From 26 points of polymorphism, only eight resulted in the post-translational amino acid changes in ND1 gene product structure. Data revealed noticeable genetic diversity (up to 4.63%) between different varieties of F. gigantica in Iran.