title: Phylogenetic relationship of Sarcocystis neurona to other members of the family Sarcocystidae based on small subunit ribosomal RNA gene sequence.
abstract: Sarcocystis neurona is a coccidial parasite that causes a neurologic disease of horses in North and South America. The natural host species are not known and classification is based on ultrastructural analysis. The small subunit ribosomal RNA (SSURNA) gene of S. neurona was amplified using polymerase chain reaction techniques and sequenced by Sanger sequencing reactions. The sequence was compared with partial sequences of S. muris, S. gigantea, S. tenella, S. cruzi, S. arieticanis, S. capracanis, Toxoplasma gondii, Eimeria tenella, and Cryptosporidium parvum. Alignments of available sites for all 10 species and alignments of the entire SSURNA sequence of S. neurona, S. muris, S. cruzi, T. gondii, and C. parvum were performed. Alignments were analyzed using maximum parsimony and maximum likelihood methods to determine relative phylogeny of these organisms. These analyses confirmed placement of S. neurona in the genus Sarcocystis and suggested a close relationship to S. muris, S. gigantea, and T. gondii. Molecular phylogeny suggests that Sarcocystis spp., which utilize the dog (Canis familiaris) as the definitive host, evolved from a common ancestor, whereas those species (including T. gondii) that utilize the cat (Felis domesticus) as the definitive host evolved from another common ancestor. This suggests a possible definitive host for S. neurona.
authors.affiliation: Department of Veterinary Sciences, University of Kentucky, Lexington 40546.
authors.forename: C K
authors.initials: CK
authors.lastname: Fenger
authors.forename: D E
authors.initials: DE
authors.lastname: Granstrom
authors.forename: J L
authors.initials: JL
authors.lastname: Langemeier
authors.forename: A
authors.initials: A
authors.lastname: Gajadhar
authors.forename: G
authors.initials: G
authors.lastname: Cothran
authors.forename: R R
authors.initials: RR
authors.lastname: Tramontin
authors.forename: S
authors.initials: S
authors.lastname: Stamper
authors.forename: J P
authors.initials: JP
authors.lastname: Dubey
mesh_terms: D000818:Animals; D001483:Base Sequence; D016384:Consensus Sequence; D017931:DNA Primers / Q000737:chemistry; D016054:DNA, Protozoan / Q000737:chemistry*; D004679:Encephalomyelitis / Q000469:parasitology / Q000662:veterinary; D017125:Genes, Protozoan; D006734:Horse Diseases / Q000469:parasitology; D006736:Horses; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D010802:Phylogeny; D016133:Polymerase Chain Reaction; D016053:RNA, Protozoan / Q000737:chemistry / Q000235:genetics; D012335:RNA, Ribosomal / Q000737:chemistry / Q000235:genetics*; D012522:Sarcocystis / Q000145:classification* / Q000235:genetics; D012523:Sarcocystosis / Q000469:parasitology / Q000662:veterinary; D016415:Sequence Alignment
chemical_list: D017931:DNA Primers; D016054:DNA, Protozoan; D016053:RNA, Protozoan; D012335:RNA, Ribosomal