Molecular characterization of Fasciola spp. from ruminants in Duhok province using the ITS1 ribosomal DNA marker

Abstract

This study aimed to characterize and identify the genotypes of Fasciola spp. isolated from sheep, goats, and cattle in Duhok province based on the ITS1 region of rDNA. About 54 adult Fasciola flukes were individually isolated from the livers of naturally infected ruminants. After morphological identification, the genomic DNA of 54 isolated Fasciola spp. was successfully extracted, and the ITS1segment (518 bp) of rDNA was amplified. The amplicons were confirmed by gel electrophoresis and yielded mono cleared bands. Five amplicons from these samples (2 sheep, 2 cattle, and 1 goat) were selected for sequencing and then compared with NCBI-GenBank sequences for genotyping and phylogenetic analysis. Sequencing analysis and the BLAST results revealed that 3/5 of the resultant sequences were F. hepatica and 2/5 were F. gigantica. The ITS1 sequences were submitted to NCBI-GenBank with accession numbers: OM920533, OM920534, OM948733, OM948683, and OM918714. Alignment analysis of the current study and GenBank ITS1 sequences showed the presence of nucleotide variations between F. hepatica and F. gigantica species (interspecific), which were enough to separate them. At the same time, they were not observed within the same species of Fasciola (intraspecific). The pairwise identity percentage of intraspecific and interspecific Fasciola isolates was 100% and 99.2-99.6%, respectively. Phylogenetic analysis of the ITS1 sequences demonstrated that the Fasciola isolates of this study were clustered into two clades (hepatica and gigantica clades). The present study concluded that both Fasciola spp. (F. hepatica and F. gigantica) existed among the infected ruminants in Duhok province, and are closely related to intraspecific Fasciola isolates from different countries in the Middle East, Asia, Europe, and Africa.