title: Genetic analysis of Fasciola isolates from cattle in Korea based on second internal transcribed spacer (ITS-2) sequence of nuclear ribosomal DNA.
abstract: Nuclear ribosomal DNA sequence of the second internal transcribed spacer (ITS-2) has been used efficiently to identify the liver fluke species collected from different hosts and various geographic regions. ITS-2 sequences of 19 Fasciola samples collected from Korean native cattle were determined and compared. Sequence comparison including ITS-2 sequences of isolates from this study and reference sequences from Fasciola hepatica and Fasciola gigantica and intermediate Fasciola in Genbank revealed seven identical variable sites of investigated isolates. Among 19 samples, 12 individuals had ITS-2 sequences completely identical to that of pure F. hepatica, five possessed the sequences identical to F. gigantica type, whereas two shared the sequence of both F. hepatica and F. gigantica. No variations in length and nucleotide composition of ITS-2 sequence were observed within isolates that belonged to F. hepatica or F. gigantica. At the position of 218, five Fasciola containing a single-base substitution (C>T) formed a distinct branch inside the F. gigantica-type group which was similar to those of Asian-origin isolates. The phylogenetic tree of the Fasciola spp. based on complete ITS-2 sequences from this study and other representative isolates in different locations clearly showed that pure F. hepatica, F. gigantica type and intermediate Fasciola were observed. The result also provided additional genetic evidence for the existence of three forms of Fasciola isolated from native cattle in Korea by genetic approach using ITS-2 sequence.
authors.affiliation: National Veterinary Research and Quarantine Service (NVRQS), 480 Anyang6 dong, Anyang City 420-480, South Korea.
authors.forename: Se-Eun
authors.initials: SE
authors.lastname: Choe
authors.forename: Thuy Thi-Dieu
authors.initials: TT
authors.lastname: Nguyen
authors.forename: Tae-Gyu
authors.initials: TG
authors.lastname: Kang
authors.forename: Chang-Hee
authors.initials: CH
authors.lastname: Kweon
authors.forename: Seung-Won
authors.initials: SW
authors.lastname: Kang
mesh_terms: D000818:Animals; D002417:Cattle; D002418:Cattle Diseases / Q000469:parasitology*; D016000:Cluster Analysis; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000737:chemistry / Q000235:genetics; D005209:Fasciola / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D005211:Fascioliasis / Q000469:parasitology / Q000662:veterinary*; D008969:Molecular Sequence Data; D010802:Phylogeny; D056910:Republic of Korea; D017422:Sequence Analysis, DNA
chemical_list: D018509:DNA, Helminth; D004275:DNA, Ribosomal; D021903:DNA, Ribosomal Spacer