Fig. 3.

IFN-γ inhibits viral replication in glial-derived cultures. (A) Differentiated progenitor cultures were infected with JHMV and subsequently treated with recombinant mouse IFN-g (10 (100 U/ml). Viral titers were determined in culture supernatants at 12, 24, and 48 h p.i. IFN-γ-treated cultures had significantly (p ≤ 0.05) reduced viral titers at all time points examined. (B) Titration of IFN-γ revealed a concentration-dependent anti-viral effect with significant (p ≤ 0.05) inhibition in viral replication occurring with IFN-γ treatment of 100 or 10 U/ml. Viral titers were determined at 24 h p.i. (C) Pre-treatment of cultures with IFN-γ (100 U/ml, 24 h) enhanced anti-viral effect as demonstrated by significant reduction in viral titers at 24 h p.i. compared to cultures treated with IFN-γ at the time of infection. (D–F) Staining for viral antigen in IFN-γ-treated cultures at 24 h p.i. revealed limited syncytia formation (D, 100× magnification) and viral antigen detected in single cells (E, 200× magnification). In contrast, media controls exhibited extensive viral replication and syncytium (F, 200× magnification). ⁎p ≤ 0.05, ⁎⁎p ≤ 0.001.