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J. D. Pena, E. C. Mastrantonio, C. D. Lopes, N. M. Silva, M. M. Tannus, E. A. V. Ferro; Invasion of Retinal Cells by Toxoplasma gondii. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2671.
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© ARVO (1962-2015); The Authors (2016-present)
To analyze, in an in vitro model, the influence of the presence and distribution of heparin, one of the putative T. gondii receptors, in retinal cells as a possible cause of increased susceptibility of retinal cells to infection by Toxoplasma gondii.
Retinal cells were obtained from the eyes of E8 and E11"White Leghorn" chicken embryos by enzymatic dissociation with trypsin. The cells were plated in coverslips and after that, infected with T. gondii tachyzoites, RH strain, in a proportion of one parasite per cell. After three hours of infection, the culture medium with free parasites was removed and the cells were incubated for 18 hours in fresh medium. Chicken fibroblasts were used as controls and cultured as above. The number of cells infected with T. gondii was determined by counting 200 cells in each experimental condition, after the coverslips had been fixed with 4% paraformaldehyde and stained with Giemsa. Immunofluorescence staining with a monoclonal anti-heparin antibody was performed to determine the distribution of heparin on the surface of retinal cells as well as fibroblasts.
Our results showed that 13.25% of fibroblasts were infected (mean 3.0 SD 0.4 parasites/cell) while 25% of E11 retinal cells (mean 4.41 SD 0.41 parasites/cell), and 91,33% of E8 retinal cell (mean 18.33 SD 4.04 parasites/cell) were infected. Pre-treatement of the parasites with heparin decreased in 79% the number of infected cells and in 60% the number of parasites/cell. Immunofluorescence staining using anti-heparin antibody showed intense labeling of retinal cells, while in fibroblasts there was a more discrete staining for heparin.
In the model studied, retinal cells were more susceptible to infection by T. gondii than fibroblasts, especially E8-derived cells. Moreover, a differential distribution of heparin on the surface of these cells may facilitate adhesion and invasion by T. gondii.
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