title: Adaptation of Neospora caninum isolates to cell-culture changes: an argument in favor of its clonal population structure.
abstract: Neospora caninum, a recently recognized protozoan parasite of animals, is considered to be a major cause of bovine abortion worldwide. Although its life cycle is not completely known, recent studies suggest that the sexual stage occurs in dogs. The prevalence of sexual reproduction in N. caninum, however, is unknown. We investigated the ability of 3 N. caninum isolates (NC-1, NC-SweB1, and NC-Liverpool) to propagate asexually for approximately 250 parasite generations in a cell line in which they had not been cultured previously. The malthusian parameter of fitness was estimated for each isolate from 10 independent replicates of tachyzoites at the beginning as well as at the end of the experimental period. Derived and ancestral values for mean fitness were compared both within and among NC-1, NC-SweB1, and NC-Liverpool isolates. Results showed a significant increase in mean fitness for the 3 N. caninum isolates at the end of the experimental period. These findings indicate that N. caninum can adapt to new environmental conditions without the help of sexual recombination, supporting the idea that this parasite has, at least potentially, the capacity for maintaining clonal propagation in nature.
authors.affiliation: Departamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Ciudad Universitaria s/n, 28040 Madrid, Spain.
authors.forename: F J
authors.initials: FJ
authors.lastname: Pérez-Zaballos
authors.forename: L M
authors.initials: LM
authors.lastname: Ortega-Mora
authors.forename: G
authors.initials: G
authors.lastname: Alvarez-García
authors.forename: E
authors.initials: E
authors.lastname: Collantes-Fernández
authors.forename: V
authors.initials: V
authors.lastname: Navarro-Lozano
authors.forename: L
authors.initials: L
authors.lastname: García-Villada
authors.forename: E
authors.initials: E
authors.lastname: Costas
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D002522:Chlorocebus aethiops; D046508:Culture Techniques / Q000379:methods; D018688:Neospora / Q000254:growth & development / Q000502:physiology*; D012100:Reproduction, Asexual / Q000502:physiology*; D012692:Serial Passage / Q000662:veterinary; D014709:Vero Cells