title: Neospora caninum and Toxoplasma gondii: a novel adhesion/invasion assay reveals distinct differences in tachyzoite-host cell interactions.
abstract: This paper describes an adhesion/invasion assay, based on combined pyrrolidine dithiocarbamate (PDTC) and antibody treatment of parasites followed by quantitative real-time PCR. This PDTC-PCR assay can be used to comparatively assess the participation of host cell- and parasite-associated components during host cell adhesion and entry by Neospora caninum and Toxoplasma gondii tachyzoites, respectively, and is potentially applicable to any other apicomplexan parasite. The assay allows to determine the parasite invasion rate in relation to the overall number of parasites which interact with host cells in any given experiment, and thus represents a significant improvement to conventional microscopic assays in terms of accuracy and reproducibility. Using this assay it was possible to show that adhesion and invasion of N. caninum tachyzoites are two distinct and separated events, in that N. caninum tachyzoites preferentially utilise host cell surface chondroitin sulphates for adhesion, but not for the host cell invasion process. Application of the PDTC-PCR assay also demonstrated that N. caninum and T. gondii tachyzoites differ largely with regard to the functional involvement of proteases in adhesion and invasion of host cells. Thus, although phylogenetically closely related, N. caninum and T. gondii are biologically quite different and exhibit distinct dissimilarities with regard to host cell interactions.
authors.affiliation: Institute of Parasitology, University of Bern, Laenggass-Strasse 122, CH-3012 Bern, Switzerland. nagul@ipa.unibe.ch
authors.forename: Arunasalam
authors.initials: A
authors.lastname: Naguleswaran
authors.forename: Norbert
authors.initials: N
authors.lastname: Müller
authors.forename: Andrew
authors.initials: A
authors.lastname: Hemphill
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D002448:Cell Adhesion / Q000502:physiology; D002522:Chlorocebus aethiops; D005455:Fluorescent Antibody Technique; D006025:Glycosaminoglycans / Q000502:physiology; D006790:Host-Parasite Interactions / Q000502:physiology; D007106:Immune Sera / Q000276:immunology; D008854:Microscopy, Electron; D018688:Neospora / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011480:Protease Inhibitors / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D011817:Rabbits; D013859:Thiocarbamates / Q000494:pharmacology; D014122:Toxoplasma / Q000187:drug effects / Q000276:immunology / Q000502:physiology*; D014709:Vero Cells
chemical_list: D000975:Antioxidants; D006025:Glycosaminoglycans; D007106:Immune Sera; D011480:Protease Inhibitors; D011759:Pyrrolidines; D013859:Thiocarbamates; C020972:pyrrolidine dithiocarbamic acid