title: ICP0 inhibits the decrease of HSV amplicon-mediated transgene expression.
abstract: The herpes simplex virus (HSV) amplicon vector produces an initial host response that limits transgene expression. In this study, we hypothesized that restoration of the HSV gene infected cell protein (ICP0) into the amplicon could circumvent this host response and thus overcome silencing of encoded transgenes. To test this, we constructed an amplicon vector that encodes the ICP0 under control of its native promoter (ICP0+ amplicon). Expression of ICP0 was transient and, at a multiplicity of infection (MOI) of 1, did not significantly alter interferon (IFN)-based responses against the vector or cell kinetics/apoptosis of infected cells. Chromatin immunoprecipitation (ChIP) PCR analysis revealed that conventional amplicon DNA became associated with histone deacetylase 1 (HDAC1) immediately after infection, whereas ICP0+ amplicon DNA remained relatively unbound by HDAC1 for at least 72 hours after infection. Mice administered systemic ICP0+ amplicon exhibited significantly greater and more sustained transgene expression in their livers than did those receiving conventional amplicon, likely due to increased transcriptional or post-transcriptional activity rather than increased copy numbers of vector DNA. These findings indicate that restoration of ICP0 expression may be employed within HSV amplicon constructs to decrease transgene silencing in vitro and in vivo.
authors.affiliation: Dardinger Laboratory for Neuro-oncology and Neurosciences, Department of Neurological Surgery, James Comprehensive Cancer Center and The Ohio State University Medical Center, Columbus, Ohio 43210, USA.
authors.forename: Masataka
authors.initials: M
authors.lastname: Suzuki
authors.forename: Kazue
authors.initials: K
authors.lastname: Kasai
authors.forename: Akihiro
authors.initials: A
authors.lastname: Ohtsuki
authors.forename: Jakub
authors.initials: J
authors.lastname: Godlewski
authors.forename: Michal O
authors.initials: MO
authors.lastname: Nowicki
authors.forename: E Antonio
authors.initials: EA
authors.lastname: Chiocca
authors.forename: Yoshinaga
authors.initials: Y
authors.lastname: Saeki
mesh_terms: D000818:Animals; D001483:Base Sequence; D047369:Chromatin Immunoprecipitation; D017931:DNA Primers; D004279:DNA, Viral / Q000235:genetics; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases / Q000378:metabolism; D017874:Immediate-Early Proteins / Q000502:physiology*; D051379:Mice; D016133:Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018139:Simplexvirus / Q000235:genetics / Q000502:physiology*; D019076:Transgenes; D044767:Ubiquitin-Protein Ligases / Q000502:physiology*
chemical_list: D017931:DNA Primers; D004279:DNA, Viral; D017874:Immediate-Early Proteins; D044767:Ubiquitin-Protein Ligases; C051804:Vmw110 protein, Human herpesvirus 1; C484389:Hdac1 protein, mouse; D056284:Histone Deacetylase 1; D006655:Histone Deacetylases