Experimental Study Of Murine Ocular Toxoplasmosis Model

BackgroundToxoplasma gondii is an ubiquitous obligate intracellular parasite, which infects both humans and warm-blooded animals as a zoonotic pathogen widespread in nature. According to statistics, approximately one-third of humans worldwide are estimated to be chronically infected with Toxoplasma gondii. The prevalence of disease and the source of the infection in different geographic areas each are not identical, with different climate, eating habits and health status and so on. Ocular toxoplasmosis is damaged by toxoplasma, understanding of the disease is less in China, the pathogenesis of ocular toxoplasmosis by toxoplasma infection is not very clear, the basis of related research is rare.Abroad on the study of the disease, mostly concentrated in the study of the disease of acute infection, and for chronic infection is less. Many clinical doctor know less for the development and evolution of fundus after chronic infection by Toxoplasma gondii, so, we want to find a good method to establish model for ocular toxoplasmosis and observe the fundus and pathological changes in eyes, thus to provide certain basis for the diagnosis and treatment of ocular toxoplasmosis, the study intends to establish murine model for ocular toxoplasmosis by the method of oral infection, simulating toxoplasma chronic infection in mice, and observe the fundus and the pathological changes, provide a certain basis for further research.ObjectiveTo establish murine model for ocular toxoplasmosis and observe the fundus and pathological changes in eyes.Methods20 BALB/C mice were randomly divided into control group and the experimental group with 10 mice per group. Mice in the experimental group were fed orally with toxoplasma type II PRU strains cyst. Fundus changes were observed daily and fundus photography and fundus fluorescence angiography(FFA) were taken after 1 month,2 months and 3 months later respectively. After 3 months, serum IgG of the mice was detected by ELISA assays. The mice were killed and the eyes were exacted. Pathology damage of retina and choroid tissue was observed after HE and IHC staining.ResultsAfter three weeks, in the experimental group, fundus inflammation was found, including optic disc edema, retinal angioplerosis, edema and hemorrhage along with retinal vascular, from the beginning of the optic disc area gradually expanded to the surrounding blood vessels. These changes aggravated with time. Fundus fluorescein angiography showed the experimental group mice retinal vascular venous filling, capillary network were damaged, Leakage of fluorescein and blood vessels without filling areathese could be found, these changes aggravated with time. Significant titers change in serum IgG, significant higher than the control group (p<0.001), from the retinal and choroid tissue slice of the experimental group mice, we could see the retinal and choroid apparent edema, the gap between the organization was loose, lacuna was formed,inflammatory cell infiltration was found in tissue of retinal and choroid. From the retinal tissue slice of the experimental group mice, specific staining of Toxoplasma gondii cysts were found.ConclusionInfected mice with type II toxoplasma PRU strains via oral route could be a good way to establish animal model for ocular toxoplasmosis. We prove that acquired toxoplasmosis can also causes retinal vascular filling, retinal edema, hemorrhage, etc of inflammation of the choroid and retinal, The serum levels of IgG in the experimental group produced a humoral immune response, it is significant for further study of ocular toxoplasmosis.