Model Systems for Studying Mechanisms of Ocular Toxoplasmosis

The most common human disease caused by infection with Toxoplasma gondii is ocular toxoplasmosis, which typically is manifest as recurrent attacks of necrotizing retinal inflammation with subsequent scarring. The multilayered retina contains specialized cell populations, including endothelial cells, epithelial cells, neurons and supporting cells, all of which may be involved in this condition. In vitro investigations of basic mechanisms operating in human ocular toxoplasmosis use cellular and molecular methods that are common to the study of many pathological processes, and the novel aspect of this research is the use of human retinal cell subsets. Most in vivo research on ocular toxoplasmosis is conducted in the laboratory mouse. Experimental models involve local or systemic inoculation of parasites to induce acute disease, or sequential systemic and local parasite inoculations to trigger recurrent disease. We present methods for in vitro and in vivo studies of ocular toxoplasmosis, including dissection of the human eye, and culture and infection of differentiated cell populations from the retina, as well as induction of mouse ocular toxoplasmosis by intraocular, or sequential systemic and intraocular, inoculations, and imaging of toxoplasmic retinal lesions.