title: Genetic characterization of three unique operational taxonomic units of Eimeria from chickens in Australia based on nuclear spacer ribosomal DNA.
abstract: Coccidiosis of chickens is one of the commonest and economically most important parasitic diseases of poultry worldwide. Given the limitations of traditional approaches, molecular tools have been developed for the specific diagnosis of coccidiosis. Recently, a polymerase chain reaction (PCR)-based capillary electrophoresis (CE) method, employing genetic markers in the second internal transcribed spacer (ITS-2) of nuclear ribosomal DNA, was established for both analytical and diagnostic purposes. The application of this method to investigate the epidemiology of coccidiosis and genetic structures of Eimeria populations on commercial chicken establishments has discovered genetic variants of Eimeria (i.e., new operational taxonomic units OTU-X, OTU-Y and OTU-Z) which were (based on CE analysis) distinct from those of species of Eimeria identified previously in chickens in Australia. The present characterization of these OTUs, based on their ITS-2 sequences and phylogenetic analyses of selected sequence data, provides first evidence to support that OTU-X represents a population variant of Eimeria maxima, and that OTU-Y and OTU-Z represent cryptic species of Eimeria. Further biological and genetic studies are needed to rigorously test these proposals and establish the specific status of these OTUs and their importance as pathogens in chickens. An understanding of the epidemiology of these population variants or cryptic species in Australia is central to designing and implementing effective vaccination and control strategies.
authors.affiliation: Department of Veterinary Science, The University of Melbourne, 250 Princes Highway, Werribee, Victoria 3030, Australia.
authors.forename: Cinzia
authors.initials: C
authors.lastname: Cantacessi
authors.forename: Shane
authors.initials: S
authors.lastname: Riddell
authors.forename: Genevieve M
authors.initials: GM
authors.lastname: Morris
authors.forename: Timothy
authors.initials: T
authors.lastname: Doran
authors.forename: Wayne G
authors.initials: WG
authors.lastname: Woods
authors.forename: Domenico
authors.initials: D
authors.lastname: Otranto
authors.forename: Robin B
authors.initials: RB
authors.lastname: Gasser
mesh_terms: D000818:Animals; D001315:Australia / Q000453:epidemiology; D001483:Base Sequence; D002645:Chickens / Q000469:parasitology*; D003048:Coccidiosis / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology / Q000662:veterinary*; D016054:DNA, Protozoan / Q000737:chemistry / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics*; D004539:Eimeria / Q000145:classification / Q000235:genetics; D019075:Electrophoresis, Capillary / Q000379:methods / Q000662:veterinary; D014644:Genetic Variation; D008969:Molecular Sequence Data; D010802:Phylogeny; D016133:Polymerase Chain Reaction / Q000379:methods / Q000662:veterinary; D011201:Poultry Diseases / Q000175:diagnosis / Q000453:epidemiology / Q000469:parasitology*; D016415:Sequence Alignment
chemical_list: D016054:DNA, Protozoan; D021903:DNA, Ribosomal Spacer