Distinctive Roles for Type I and Type II Interferons and Interferon Regulatory Factors in the Host Cell Defense against Varicella-zoster Virus.

Both type I and type II interferons (IFNs) have been implicated in the host defense against varicella zoster virus (VZV)， a common human herpesvirus that causes varicella and zoster. The purpose of this study was to compare their contributions to the control of VZV replication， to identify the signaling pathways that are critical for mediating their antiviral activity， and to define mechanisms by which the virus counteracts their effects. IFNγ was much more potent than IFNα in blocking VZV infection， which was associated with a differential induction of the interferon regulatory factor (IRF) proteins， IRF1 and IRF9， respectively. These observations account for the clinical experience that while the formation of VZV skin lesions is controlled initially by local immunity， adaptive virus-specific T cell responses are required to prevent life-threatening VZV infections.While both Type I and Type II IFNs are involved in the control of herpesvirus infections in the human host， to our knowledge， their relative contributions to the restriction of viral replication and spread have not been assessed. We report that IFNγ has more potent activity than IFNα against VZV. Findings from this comparative analysis show that the IFNα-IRF9 axis functions as a first line of defense to delay the onset of viral replication and spread whereas the IFNγ-IRF1 axis has the capacity to block the infectious process. Our findings underscore the importance of IRFs in IFN regulation of herpesvirus infection and account for the clinical experience of initial control of VZV skin infection， attributable to IFNα production， together the requirement for induction of adaptive IFNγ-producing VZV specific T cells to resolve the infection.