Characterization of Fasciola hepatica genotypes from cattle and sheep in Iran using cytochrome C oxidase gene (CO1)

The present study compared the genetic variation among 19 different isolates of Fasciola hepatica from cattle and sheep in different areas of Iran using sequence data for mitochondrial DNA gene, the subunit 1 of cytochrome C oxidase gene (CO1). Four different CO1 genotypes were detected among F. hepatica isolates that showed five variable nucleotide positions (accession nos.; GQ398051, GQ398052, GQ398053, GQ398054). Nucleotide sequence variation among 19 isolates for CO1 analyzed in this study ranged from 0% to 0.98% in Iran. Among the five polymorphism sites identified in this study, only one (T to G at position 51 in 5'end of GQ175362) resulted in putative amino acid alteration of phenylalanine (TTT) to leucine (TTG) in CO1. A phylogenetic analysis of the sequence data revealed that host associations and geographic location are likely not useful markers for Fasciola genotype classification. In addition, morphological analysis showed that the ratios of body length and body width of some (n = 5) of the 19 examined F. hepatica isolates were intermediate between F. hepatica and Fasciola gigantica, representing the substantial polymorphism of the F. hepatica species and the difficulty in the accurate recognition based on morphological features. In conclusion, Iranian F. hepatica exhibited the presence of considerable genetic diversity at CO1.