RESUMO
Neospora caninum is one of the most important causes of bovine abortion, but isolation of live parasites from infected tissue is difficult. The aims of the present study were to obtain new isolates of N. caninum from congenitally infected asymptomatic newborn cattle in Argentina and to perform characterization by multilocus-microsatellite analysis. Five clinically normal born calves, with demonstrable N. caninum antibodies in precolostrum serum by indirect fluorescent antibody test, were euthanized and their brain samples were processed for histopathological, immunohistochemical, polymerase chain reaction (PCR) analysis, and for bioassay in γ-interferon knockout (GKO) mice. Although N. caninum DNA was detected in brain from all the calves by PCR, viable N. caninum was isolated in GKO mice from only one calf. Neospora caninum tachyzoites of this Argentinean isolate, designated NC-Argentina LP1, were propagated in VERO cell cultures seeded with tachyzoites from the infected GKO mice tissues. Multilocus-microsatellite typing on DNA derived from cell cultured tachyzoites revealed a unique genetic pattern, different from reported isolates. This is the first bovine isolation and genetic characterization of N. caninum in Argentina.
Assuntos
Doenças dos Bovinos/parasitologia , Coccidiose/veterinária , Neospora/isolamento & purificação , Animais , Animais Recém-Nascidos , Anticorpos Antiprotozoários/sangue , Argentina/epidemiologia , Bioensaio/veterinária , Encéfalo/parasitologia , Bovinos , Doenças dos Bovinos/epidemiologia , Coccidiose/epidemiologia , Coccidiose/parasitologia , Feminino , Técnica Indireta de Fluorescência para Anticorpo/veterinária , Imuno-Histoquímica/veterinária , Masculino , Camundongos , Camundongos Knockout , Repetições de Microssatélites , Dados de Sequência Molecular , Tipagem de Sequências Multilocus/veterinária , Neospora/genética , Neospora/imunologia , Reação em Cadeia da Polimerase , Estudos SoroepidemiológicosRESUMO
Bovine neosporosis is an important disease in dairy herds in Argentina. Embryo transfer (ET) technology offers the opportunity to minimize vertical transmission of neosporosis. The objective of this work was to compare the serological status and the incidence of abortion between heifers obtained via natural service and heifers obtained by ET from Neospora-infected cows. Progeny from eight Neospora-infected cows belonging to a commercial dairy farm where ET was routinely performed were studied. Between 1996 and 2001, 16 and 15 heifers were obtained by natural service and ET, respectively. Serostatus and reproductive performance were recorded in both progeny. Serostatus was determined by indirect fluorescent antibody test (IFAT). All heifers obtained by natural service were seropositive and six of 16 pregnancies ended in abortion. All heifers obtained by ET were seronegative and only two abortions of 15 pregnancies were recorded.