title: The Mitochondrial Genomes of the Zoonotic Canine Filarial Parasites Dirofilaria (Nochtiella) repens and Candidatus Dirofilaria (Nochtiella) hongkongensis Provide Evidence for Presence of Cryptic Species.
abstract: Cutaneous dirofilariosis is a canine mosquito-borne zoonosis that can cause larva migrans disease in humans. Dirofilaria repens is considered an emerging pathogen occurring with high prevalence in Mediterranean areas and many parts of tropical Asia. In Hong Kong, a second species, Candidatus Dirofilaria hongkongensis, has been reported. The present study aimed to compare mitochondrial genomes from these parasites and to obtain population genetic information.
  
  
  
  Complete mitochondrial genomes were obtained by PCR and Sanger sequencing or ILLUMINA sequencing for four worms. Cytochrome oxidase subunit 1 sequences identified three as D. repens (all from Europe) and one as C. D. hongkongensis (from India). Mitochondrial genomes have the same organization as in other spirurid nematodes but a higher preference for thymine in the coding strand. Phylogenetic analysis was in contradiction to current taxonomy of the Onchocercidae but in agreement with a recent multi-locus phylogenetic analysis using both mitochondrial and nuclear markers. D. repens and C. D. hongkongensis sequences clustered together and were the common sister group to Dirofilaria immitis. Analysis of a 2.5 kb mitochondrial genome fragment from macrofilaria or canine blood samples from Europe (42), Thailand (2), India (1) and Vietnam (1) revealed only small genetic differences in the D. repens samples including all European and the Vietnam sample. The Indian C. D. hongkongensis and the two Thai samples formed separate clusters and differences were comparatively large.
  
  
  
  Genetic differences between Dirofilaria spp. causing cutaneous disease can be considerable whereas D. repens itself was genetically quite homogenous. C. D. hongkongensis was identified for the first time from the Indian subcontinent. The full mitochondrial genome sequence strengthens the hypothesis that it represents an independent species and the Thai samples might represent another cryptic species, Candidatus Dirofilaria sp. 'Thailand II', or a quite divergent population of C. D. hongkongensis.
authors.affiliation: Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Esra
authors.initials: E
authors.lastname: Yilmaz
authors.affiliation: Institute of Medical Microbiology, Justus-Liebig-University, Giessen, Germany; German Center for Infection Research (DZIF), Partner site Giessen-Marburg-Langen, Campus Giessen, Giessen, Germany.
authors.forename: Moritz
authors.initials: M
authors.lastname: Fritzenwanker
authors.affiliation: IDEXX Laboratories, Ludwigsburg, Germany.
authors.forename: Nikola
authors.initials: N
authors.lastname: Pantchev
authors.affiliation: Institut für Parasitologie, Universität Leipzig, Leipzig, Germany.
authors.forename: Mathias
authors.initials: M
authors.lastname: Lendner
authors.affiliation: Department of Parasitology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Sirichit
authors.initials: S
authors.lastname: Wongkamchai
authors.affiliation: Department of Veterinary Medicine, University of Bari, Bari, Italy.
authors.forename: Domenico
authors.initials: D
authors.lastname: Otranto
authors.affiliation: Division of Infectious Diseases and Tropical Medicine, Medical Centre of the University of Munich (LMU); German Center for Infection Research (DZIF), Partner site Munich, Germany.
authors.forename: Inge
authors.initials: I
authors.lastname: Kroidl
authors.affiliation: Section Clinical Tropical Medicine, Department of Infectious Diseases, Heidelberg University Hospital, Heidelberg, Germany.
authors.forename: Martin
authors.initials: M
authors.lastname: Dennebaum
authors.affiliation: Immunology Department, Institute of Biotechnology, Ha Noi, Viet Nam.
authors.forename: Thanh Hoa
authors.initials: TH
authors.lastname: Le
authors.affiliation: Department of Parasitology, Viet Nam Veterinary Medical University, Ha Noi, Viet Nam.
authors.forename: Tran
authors.initials: T
authors.lastname: Anh Le
authors.affiliation: Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Sabrina
authors.initials: S
authors.lastname: Ramünke
authors.affiliation: Bayer Animal Health GmbH, Monheim, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Schaper
authors.affiliation: Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: von Samson-Himmelstjerna
authors.affiliation: University Medical Center, Hamburg-Eppendorf, Germany.
authors.forename: Sven
authors.initials: S
authors.lastname: Poppert
authors.affiliation: Institute for Parasitology and Tropical Veterinary Medicine, Freie Universität Berlin, Berlin, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Krücken
mesh_terms: D000818:Animals; D001208:Asia / Q000453:epidemiology; D009033:Culicidae / Q000469:parasitology; D004182:Dirofilaria / Q000235:genetics* / Q000302:isolation & purification*; D060348:Dirofilaria repens / Q000235:genetics* / Q000302:isolation & purification; D004184:Dirofilariasis / Q000453:epidemiology / Q000469:parasitology*; D004283:Dog Diseases / Q000453:epidemiology / Q000469:parasitology; D004285:Dogs; D003576:Electron Transport Complex IV / Q000235:genetics; D005060:Europe / Q000453:epidemiology; D054629:Genome, Mitochondrial; D006801:Humans; D007194:India / Q000453:epidemiology; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D013785:Thailand / Q000453:epidemiology; D014744:Vietnam / Q000453:epidemiology
chemical_list: D003576:Electron Transport Complex IV