Genetic Characterization of Fasciola spp. from Tonekabon City (Northern Iran) Based on the Ribosomal Internal Transcribed Spacer Regions

Fasciolosis caused by Fasciola spp. (Platyhelminthes: Trematoda: Digenea) is considered the most important helminth infection of ruminants in tropical countries, causing considerable socioeconomic problems. In the endemic regions of the North of Iran, Fasciola hepatica and F. gigantica have been previously characterized on the basis of morphometric differences, but the use of molecular markers is necessary to distinguish exactly between species and intermediate forms. Samples identified morphologically as Fasciola sp. in buffaloes and goats from Tonekabon city (northern Iran) were genetically characterised by sequences of the first (ITS-1), the 5.8S, and second (ITS-2) Internal Transcribed Spacers (ITS) of nuclear ribosomal DNA (rDNA). Comparison of the ITS of the North Iranian samples with sequences of Fasciola spp. from GenBank showed that the specimens examined had sequences identical to those of F. hepatica (n=22, 45.83%) and F. gigantica (n=17, 35.42%), which differed from each other in different variable nucleotide positions of ITS region sequences, and their intermediate forms (n=9, 18.75%), which had nucleotides overlapped between the two Fasciola species in all the positions. The nucleotide sequencing of ITS rDNA of F. hepatica and F. gigantica from Tonekabon city showed no nucleotide variation in the ITS-1 and ITS-2 rDNA sequences, versus two ITS-2 haplotypes in standard F. hepatica reported in GenBank. The intergenic transcribed spacers ITS-1 and ITS-2 showed to allow a reliable approach for the genetic differentiation of Fasciola spp., providing foundation for further studies on F. hepatica, F. gigantica and their intermediate forms in the endemic areas.