In vitro development of Neospora caninum (Protozoa: Apicomplexa) from dogs.

The development of Neospora caninum isolated from naturally infected dogs was examined in mammalian cell cultures. Tachyzoites developed by endodyogeny when inoculated onto bovine monocyte or bovine cardiopulmonary artery endothelial cell cultures. Tachyzoites were 5.0 by 2.0 microns and had a posteriorly located nucleus. Cytopathogenic effects of parasite development consisted of the formation of holes in the cell monolayer associated with the rupture of infected host cells. Serial passage of tachyzoites was achieved by subinoculation of tachyzoites onto non-infected bovine monocyte cell cultures. It appears that N. caninum can be continuously grown in cell cultures.