OAS and PKR Are Not Required for the Antiviral Effect of Ad:IFN-γAgainst Acute HSV-1 in Primary Trigeminal Ganglia Cultures

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Abstract
Three interferon-γ (IFN-γ)-induced antiviral pathways have been reported. Involved antiviral proteins include: Mx, RNase L/2′,5′-OAS, and protein kinase R (PKR). Involvement of OAS and PKR in IFN-γ-induced anti-herpes simplex virus-1 (HSV-1) pathways has not been reported previously, but IFN-γ induces OAS and PKR when other viruses invade the nervous system. The aim of the current study was to determine if the absence of intact OAS and PKR antiviral pathways affects the antiviral activity of IFN-γ during acute HSV-1 infection within the trigeminal ganglia (TG). To investigate this, primary TG cultures were established using TGs removed from C57BL/6 (wild-type), RNase L knockout, and RNase L/PKR double knockout mice. Each dissociated TG was transduced with an adenoviral vector containing an IFN-γ transgene or vector alone. Viral titers after HSV-1 infection of primary TG cell cultures were determined. Significant differences in viral titer for Ad:Null-transduced vs. Ad:IFN-γ-tranduced TG were found in each genotype. However, the effectiveness of Ad:IFN-γ was not reduced in the absence of both OAS and PKR pathways or OAS alone. Recombinant IFN-γ also exhibited anti-HSV-1 activity. The effectiveness of the IFN-γ transgene was lost in primary TG cells from IFN-γ receptor knockout mice. The data suggest that novel anti-HSV-1 mechanisms are induced by IFN-γ.