Role of Indoleamine-2,3-Dioxygenase in Alpha/Beta and Gamma Interferon-Mediated Antiviral Effects against Herpes Simplex Virus Infections

Gamma interferon (IFN-γ)-mediated indoleamine-2,3-dioxygenase (IDO) activity in human astrocytoma cells and in native astrocytes was found to be responsible for the inhibition of herpes simplex virus replication. The effect is abolished in the presence of excess amounts ofl-tryptophan. Both IFN-α and IFN-β restricted herpes simplex virus replication in both cell types, but (in contrast to the results seen with IFN-γ) the addition of an excess amount ofl-tryptophan did not inhibit the induced antiviral effect.