title: Mitochondrial genomic comparison of Clonorchis sinensis from South Korea with other isolates of this species.
abstract: Clonorchiasis is a neglected tropical disease that affects >35 million people mainly in China, Vietnam, South Korea and some parts of Russia. The disease-causing agent, Clonorchis sinensis, is a liver fluke of humans and other piscivorous animals, and has a complex aquatic life cycle involving snails and fish intermediate hosts. Chronic infection in humans causes liver disease and associated complications including malignant bile duct cancer. Central to control and to understanding the epidemiology of this disease is knowledge of the specific identity of the causative agent as well as genetic variation within and among populations of this parasite. Although most published molecular studies seem to suggest that C. sinensis represents a single species and that genetic variation within the species is limited, karyotypic variation within C. sinensis among China, Korea (2n=56) and Russian Far East (2n=14) suggests that this taxon might contain sibling species. Here, we assessed and applied a deep sequencing-bioinformatic approach to sequence and define a reference mitochondrial (mt) genome for a particular isolate of C. sinensis from Korea (Cs-k2), to confirm its specific identity, and compared this mt genome with homologous data sets available for this species. Comparative analyses revealed consistency in the number and structure of genes as well as in the lengths of protein-coding genes, and limited genetic variation among isolates of C. sinensis. Phylogenetic analyses of amino acid sequences predicted from mt genes showed that representatives of C. sinensis clustered together, with absolute nodal support, to the exclusion of other liver fluke representatives, but sub-structuring within C. sinensis was not well supported. The plan now is to proceed with the sequencing, assembly and annotation of a high quality draft nuclear genome of this defined isolate (Cs-k2) as a basis for a detailed investigation of molecular variation within C. sinensis from disparate geographical locations in parts of Asia and to prospect for cryptic species.
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Daxi
authors.initials: D
authors.lastname: Wang
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Neil D
authors.initials: ND
authors.lastname: Young
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Anson V
authors.initials: AV
authors.lastname: Koehler
authors.affiliation: Cancer and Stem Cell Biology, Duke-NUS Graduate Medical School, Republic of Singapore.
authors.forename: Patrick
authors.initials: P
authors.lastname: Tan
authors.affiliation: Department of Parasitology and Tropical Medicine, and Institute of Health Sciences, Gyeongsang National University, School of Medicine, Jinju, Republic of Korea.
authors.forename: Woon-Mok
authors.initials: WM
authors.lastname: Sohn
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia.
authors.forename: Pasi K
authors.initials: PK
authors.lastname: Korhonen
authors.affiliation: Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Parkville, Victoria, Australia. Electronic address: robinbg@unimelb.edu.au.
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
mesh_terms: D000818:Animals; D001483:Base Sequence; D002681:China / Q000453:epidemiology; D003003:Clonorchiasis / Q000453:epidemiology* / Q000469:parasitology; D003004:Clonorchis sinensis / Q000145:classification / Q000235:genetics* / Q000302:isolation & purification; D050259:Genes, Mitochondrial; D014644:Genetic Variation; D054629:Genome, Mitochondrial; D059014:High-Throughput Nucleotide Sequencing; D006801:Humans; D010802:Phylogeny; D018510:RNA, Helminth / Q000235:genetics*; D056910:Republic of Korea / Q000453:epidemiology; D012426:Russia / Q000453:epidemiology
chemical_list: D018510:RNA, Helminth
keywords: Clonorchis sinensis; Genetic variation; Mitochondrial genome