title: First Molecular Characterization of Theileria ornithorhynchi Mackerras, 1959: yet Another Challenge to the Systematics of the Piroplasms.
abstract: Piroplasms, tick-transmitted Apicomplexa of the genera Theileria, Babesia and Cytauxzoon, are blood-borne parasites of clinical and veterinary importance. The order Piroplasmida shows a puzzling systematics characterized by multiple clades, soft polytomies and paraphyletic/polyphyletic genera. In the present study, screening of platypuses (Ornithorhynchus anatinus), was performed to infer the parasite molecular phylogeny. DNA was extracted from blood, ectoparasites and tick eggs and the 18S rRNA- hsp70-genes were used for the phylogenetic reconstructions. Microscopic analyses detected pleomorphic intra-erythrocytic organisms and tetrads consistent with previous descriptions of Theileria ornithorhynchi Mackerras, 1959, but observation of possible schizonts could not be confirmed. DNA sequences obtained from blood and ticks allowed resolving the systematics of the first piroplasm infecting a monotreme host. Molecularly, T. ornithorhynchi formed a novel monophyletic group, basal to most known piroplasms' clades. The ancestral position of this clade, isolated from an ancient lineage of mammalian host appears particularly fascinating. The present paper discusses the inadequacies of the current molecular systematics for the Piroplasmida and the consequences of incomplete sampling, morphology-based classification and ambiguous microscopic identifications. Likely when the current sampling bias is rectified and more sequence data is made available, the phylogenetic position of T. ornithorhynchi will be further contextualized without ambiguity.
authors.affiliation: Vector- and Water-Borne Pathogen Research Group, School of Veterinary & Life Sciences, Molecular and Biomedical Sciences, Murdoch University, Murdoch WA, 6150, Australia. Electronic address: a.paparini@murdoch.edu.au.
authors.forename: Andrea
authors.initials: A
authors.lastname: Paparini
authors.affiliation: College of Veterinary Medicine, School of Veterinary and Life Sciences, Murdoch University, 90 South Street, Murdoch, Western Australia, 6150.
authors.forename: James
authors.initials: J
authors.lastname: Macgregor
authors.affiliation: Vector- and Water-Borne Pathogen Research Group, School of Veterinary & Life Sciences, Molecular and Biomedical Sciences, Murdoch University, Murdoch WA, 6150, Australia.
authors.forename: Una M
authors.initials: UM
authors.lastname: Ryan
authors.affiliation: Vector- and Water-Borne Pathogen Research Group, School of Veterinary & Life Sciences, Molecular and Biomedical Sciences, Murdoch University, Murdoch WA, 6150, Australia.
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Irwin
mesh_terms: D000818:Animals; D016054:DNA, Protozoan / Q000235:genetics; D005260:Female; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D018884:Ixodes / Q000469:parasitology*; D008969:Molecular Sequence Data; D010802:Phylogeny; D010987:Platypus / Q000469:parasitology*; D015800:Protozoan Proteins / Q000235:genetics; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000662:veterinary; D013648:Tasmania; D016794:Theileria / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D013801:Theileriasis / Q000469:parasitology
chemical_list: D016054:DNA, Protozoan; D018840:HSP70 Heat-Shock Proteins; D015800:Protozoan Proteins; D012337:RNA, Ribosomal, 18S
keywords: 18S rDNA; Bayesian analysis; Piroplasmida.; Platypus; molecular phylogeny; systematics