title: Modulation of human herpesvirus 8/Kaposi's sarcoma-associated herpesvirus replication and transcription activator transactivation by interferon regulatory factor 7.
abstract: Human herpesvirus 8 (HHV-8)/Kaposi's sarcoma-associated herpesvirus infection goes through lytic and latent phases that are regulated by viral gene products, but very little is known about the involvement of host proteins. The replication and transcription activator (RTA) is a viral protein sufficient to initiate lytic replication by activating downstream genes, including the viral early gene open reading frame 57 (ORF 57), which codes for a posttranscriptional activator. In this study, we demonstrate that cellular interferon regulatory factor 7 (IRF-7) negatively regulates this process by competing with RTA for binding to the RTA response element in the ORF 57 promoter to down-regulate RTA-induced gene expression. We also show that alpha interferon represses RTA-mediated transactivation and that repression involves IRF-7. Our study indicates that upon HHV-8 infection, the host responds by suppression of lytic gene expression through binding of IRF-7 to the lytic viral gene promoter. These findings suggest that HHV-8 has developed a novel mechanism to induce but then subvert the innate antiviral response, specifically the interferon-signaling pathway, to regulate RTA activity and ultimately the viral latent/lytic replicative cycle.
authors.affiliation: Nebraska Center for Virology and School of Biological Sciences, University of Nebraska--Lincoln, 1901 Vine St., Lincoln, NE 68588-0666, USA.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Wang
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Luwen
authors.initials: L
authors.lastname: Zhang
authors.forename: William
authors.initials: W
authors.lastname: Harrington
authors.forename: John T
authors.initials: JT
authors.lastname: West
authors.forename: Charles
authors.initials: C
authors.lastname: Wood
mesh_terms: D004268:DNA-Binding Proteins / Q000378:metabolism / Q000502:physiology*; D015967:Gene Expression Regulation, Viral; D019288:Herpesvirus 8, Human / Q000502:physiology*; D006801:Humans; D017874:Immediate-Early Proteins / Q000378:metabolism*; D050839:Interferon Regulatory Factor-7; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*; D014764:Viral Proteins / Q000378:metabolism*; D014779:Virus Replication / Q000502:physiology
chemical_list: D004268:DNA-Binding Proteins; C494234:IRF7 protein, human; D017874:Immediate-Early Proteins; D050839:Interferon Regulatory Factor-7; C417604:Rta protein, Human herpesvirus 8; D015534:Trans-Activators; D014764:Viral Proteins