In vitroisolation and characterization of aNeospora sp. from aborted bovine foetuses

Abstract

SUMMARYANeospora sp. was isolated from the brains of two aborted bovine foetuses and grown continuouslyin vitroin bovine cell cultures. A comparison of the antigenic reactivity ofin vitrocultivated tachyzoites with polyclonal antisera toNeospora caninum, Hammondia hammondi or Toxoplasma gondiirevealed that the bovine protozoal isolates were similar toN. caninumand antigenically distinct fromT. gondii. Tachyzoites of both bovine isolates had similar ultrastructural features, including an apical polar ring, conoid, electron-dense rhoptries and micronemes. The orientation of the micronemes, presence of micropores and a large number of electron-dense granules in the posterior portion of the bovine isolate tachyzoites differed from previous descriptions ofN. caninum in vivo. Tachyzoites of the bovine isolates were ultrastructurally more similar toin vitrocultivatedN. caninumtachyzoites than to tachyzoites ofT. gondiiorH. hammondi. The antigenic and ultrastructural similarities betweenN. caninumand the protozoal parasites isolated from aborted bovine foetuses in this study support the proposition that these parasites belong to the genusNeospora.