title: New molecular evidence that Teladorsagia circumcincta (Nematoda: Trichostrongylidea) is a species complex.
abstract: In the polymorphic Teladorsagia circumcincta (morphs circumcincta and trifurcata), a sheep and goat line (SGL) and a goat line (GL) have been previously described on the basis of the malate dehydrogenase allozyme polymorphism (MDH-2) and of the morphology of the dorsal ray. The GL were never found alone in 1 host, so the status of species was not given to these 2 lines. To investigate further whether there are other genetic markers that will delineate them, we collected T. circumcincta worms from goat and sheep at 8 farms in Touraine (west-central France). The worms were identified individually as being SGL or GL on the basis of MDH-2 polymorphism. This distinctiveness was corroborated by sequences of the beta-tubulin isotype I gene, the second internal transcribed spacer (ITS2) of their rDNA, and the nicotinamide dehydrogenase (ND4) gene of their mDNA. The extent of the divergence in the 3 additional genetic markers was such that SGL and GL may be considered as 2 species. A third putative species was found in the SGL line based exclusively on the ND4 gene. These findings suggest that T. circumcincta is a species complex and that further investigation is required on a wider geographic scale.
authors.affiliation: INRA, Station de Pathologie Aviaire et de Parasitologie, Nouzilly, France.
authors.forename: Vincent
authors.initials: V
authors.lastname: Leignel
authors.forename: Jacques
authors.initials: J
authors.lastname: Cabaret
authors.forename: Jean F
authors.initials: JF
authors.lastname: Humbert
mesh_terms: D000818:Animals; D001483:Base Sequence; D018509:DNA, Helminth / Q000032:analysis / Q000235:genetics; D021903:DNA, Ribosomal Spacer; D015511:Goat Diseases / Q000469:parasitology; D006041:Goats / Q000469:parasitology*; D008291:Malate Dehydrogenase / Q000235:genetics; D008297:Male; D008969:Molecular Sequence Data; D009245:NADH Dehydrogenase / Q000235:genetics; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D012756:Sheep / Q000469:parasitology*; D012757:Sheep Diseases / Q000469:parasitology; D014251:Trichostrongyloidea / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D014252:Trichostrongyloidiasis / Q000469:parasitology / Q000662:veterinary*; D014404:Tubulin / Q000235:genetics
chemical_list: D018509:DNA, Helminth; D021903:DNA, Ribosomal Spacer; C098483:NADH dehydrogenase subunit 4; D014404:Tubulin; D008291:Malate Dehydrogenase; D009245:NADH Dehydrogenase