In Astrocytes the Accumulation of the Immunity-Related GTPases Irga6 and Irgb6 at the Vacuole of Toxoplasma gondii Is Dependent on the Parasite Virulence
Figure 1
Growth of different T. gondii strains in IFNγ-stimulated astrocytes. ((a)–(e)) Astrocytes were prestimulated with the indicated IFNγ concentrations and infected for 72 h with different T. gondii strains (MOI: 1). T. gondii growth was measured by incorporation of 3H-uracile for the last 24 h of culture using the fact that T. gondii is able to incorporate uracile selectively, while in host cells the necessary enzyme is lacking [28]. Uracile incorporation after infection with the different T. gondii strains in unstimulated astrocytes was set to 100%, and incorporation in stimulated astrocytes was calculated accordingly. Depicted is mean ± standard error of mean (SEM) of four independent experiments with triplicates (; ). Avirulent T. gondii strains (white; (a)–(c)) were tested as well as virulent strains (black; (d), (e)). (f) Astrocytes were prestimulated with 100 U/mL IFNγ and pulse-infected with the indicated T. gondii strains (MOI: 10). After an incubation time of 48 h, infected cells were fixed and tachyzoites per PV were counted by identification of DAPI-labelled T. gondii nuclei (mean ± SEM, ). ((g)-(h)) Astrocytes were prestimulated with 100 U/mL IFNγ and infected with T. gondii (MOI: 10), and after the indicated time points the vacuoles per 100 cells were identified via GRA7 staining. Depicted is mean ± SEM for three independent infection experiments for every strain in duplicates with the averaged results over the avirulent strains (ME49 and NTE, white) and virulent strains (BK and RH, black).
