Tissue Culture and Explant Approaches to Studying and VisualizingNeospora caninumand Its Interactions with the Host Cell

Abstract

Neospora caninumis an apicomplexan parasite first mentioned in 1984 as a causative agent of neuromuscular disease in dogs. It is closely related toToxoplasma gondiiandHammondia heydorni, and its subsequent description in 1988 has been, and still is, accompanied by discussions on the true phylogenetical status of the genusNeospora.N. caninumexhibits features that clearly distinguish this parasite from other members of the Apicomplexa, including distinct ultrastructural properties, genetic background, antigenic composition, host cell interactions, and the definition of the dog as a final host. Most importantly,N. caninumhas a particular significance as a cause of abortion in cattle.In vitroculture has been indispensable for the isolation of this parasite and for investigations on the ultrastructural, cellular, and molecular characteristics of the different stages ofN. caninum. Tissue culture systems include maintenance ofN. caninumtachyzoites, which represent the rapidly proliferating stage in a large number of mammalian host cells, culture of parasites in organotypic brain slice cultures as a tool to investigate cerebral infection byN. caninum, and the use of techniques to induce the stage conversion from the tachyzoite stage to the slowly proliferating and tissue cyst-forming bradyzoite stage. This review will focus on the use of these tissue culture models as well as light- and electron-microscopical techniques for studies onN. caninumtachyzoites and bradyzoites, and on the physical interactions between parasites and host cells.