Figure 4: IFNγ-induced IDO protein has a minimal effect on virus replication. (a) SNB19 or U251 cells were pretreated with varying concentrations of IFNγ (0–500 U/mL) in media supplemented with 100 μg/mL of L tryptophan. After 3 days of incubation, IDO activity was measured by determining kynurenine content in the cell supernatants. (b) U251 or SNB19 cell lines were pretreated or mock treated with IFNγ (500 U/mL) with or without 1-MT (300 μM) 24 h prior to infection with JD0G or KOS virus, and the supernatants were titered at 24 hpi. The data represent the average of two independent infections, and the error bars represent the standard deviation; these data are representative of replicate experiments.