Interferon-gamma induces resistance in primary monocytes against human immunodeficiency virus type-1 infection

Treatment of monocytes with interferon-gamma 1 day before, or at the time of infection with human immunodeficiency virus type-1 (HIV-1) induced complete resistance in monocytes against HIV-1 infection. There was no evidence of viral RNA, proviral DNA, p24 antigen, or reverse transcriptase activity through 2 weeks after inoculation. Ultrastructural examination of these cells showed no detectable virus particles. When interferon-gamma was added to monocytes 1 to 3 days post-infection, virus integration occurred, but the viral expression was either ablated (1 day post-infection) or significantly inhibited (3 days post-infection). Treatment of monocytes with interferon-gamma before or after infection with HIV-1 produced significantly higher levels of tumor necrosis factor-alpha and interleukin-8 than untreated or uninfected monocytes. These results suggest that altered regulation of cytokines may mediate antiviral activity of interferon-gamma in monocytes.