Abstract
SUMMARYPartial mitochondrial cytochromecoxidase subunit I (mt COI) sequences were generated from:Toxoplasma gondii(strains CTG, GTI, MAS, ME49, PTG, TgCatBr5, TgCat, Br64, TgCgCal, TgToucan);Neospora caninum(Strain NC1);Hammondia hammondi(Strain H.H–20);H. heydorni; H. cf.triffittae; Cystoisospora felis; C. suis; C. canis; C. rivolta; C. cf.ohioensis; Caryospora bigenetica; Sarcocystis rileyi; andS. neurona. Nuclear 18S rDNA sequences were generated forH. heydorni, H. hammondi, C. suis, C. canis, C. felis, C. rivolta, C. cf.ohioensis, S. neurona, andS. rileyi. Aligned, concatenated 18S rDNA and COI sequences were Bayesian analysed using partitioned nucleotide substitution models [HKY + I + G for 18S; GTR + I + G codon (code = metmt) for COI]. Phylogenetic hypotheses supported a monophyletic Sarcocystidae and its subfamilie with two major clades within the Toxoplasmatinae: (1) a monophyletic clade ofCystoisosporaspp. withNephroisospora eptesici; and (2) a clade ofToxoplasma, NeosporaandHammondia. Within the latter,Hammondiawas shown to be paraphyletic;H. heydorniandH. triffittaewere monophyletic withN. caninum[canine definitive hosts (DHs)], whereasH. hammondiwas monophyletic withT. gondii(feline DHs). A new genus is erected to resolve the paraphyly of the genusHammondiaconfirmed using mt COI and combined 18S/COI sequence datasets.
Highlights
Coccidia in the family Sarcocystidae, the tissue coccidia, are important pathogens of many vertebrates, including humans (Velmurugan and Dubey, 2008)
Fecal specimens containing oocysts of C. felis, C. suis, C. cf. ohioensis, C. canis and H. heydorni were obtained from diagnostic fecal specimens submitted to the Animal Health Laboratory, Laboratory Services Division, University of Guelph (Guelph, ON, Canada)
Pairs of degenerate coccidia- and Sarcocystidaespecific primers designed to amplify a portion of the mitochondrial cytochrome c oxidase subunit I (mt COI) gene produced PCR products that ranged from 418 to 848 bp in length; translations of all sequences indicated that no indels existed within the region amplified by any of these primers from the sarcocystid parasites
Summary
Coccidia in the family Sarcocystidae, the tissue coccidia, are important pathogens of many vertebrates, including humans (Velmurugan and Dubey, 2008). Many species within the subfamily Toxoplasmatinae (e.g. Toxoplasma gondii, Neospora caninum, Hammondia heydorni and Hammondia hammondi) exhibit facultative or obligatory heteroxenous life cycles. Coprological identification of N. caninum, T. gondii, H. heydorni and H. hammondi is difficult because their unsporulated oocysts are morphologically indistinguishable for all practical purposes (Frenkel and Dubey, 1975; Dubey and Lindsay, 1996; Lindsay et al 1997). There are seven described genera recognized in the subfamily: Hyaloklossia Labbé 1896; Toxoplasma Nicolle & Manceaux 1908; Besnoitia Henry 1913; Cystoisospora Frenkel 1977; Hammondia Frenkel and Dubey 1975; Neospora Dubey et al 1988; and Nephroisospora Wünschmann et al 2010. Toxoplasma gondii was described from tissue cysts (bradyzoites) observed in rodents in 1908.
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