title: Replication of subgenomic hepatitis C virus replicons in mouse fibroblasts is facilitated by deletion of interferon regulatory factor 3 and expression of liver-specific microRNA 122.
abstract: Hepatitis C virus (HCV) infection causes significant morbidity, and efficient mouse models would greatly facilitate virus studies and the development of effective vaccines and new therapeutic agents. Entry factors, innate immunity, and host factors needed for viral replication represent the initial barriers that restrict HCV infection of mouse cells. Experiments in this paper consider early postentry steps of viral infection and investigate the roles of interferon regulatory factors (IRF-3 and IRF-9) and microRNA (miR-122) in promoting HCV replication in mouse embryo fibroblasts (MEFs) that contain viral subgenomic replicons. While wild-type murine fibroblasts are restricted for HCV RNA replication, deletion of IRF-3 alone can facilitate replicon activity in these cells. This effect is thought to be related to the inactivation of the type I interferon synthesis mediated by IRF-3. Additional deletion of IRF-9 to yield IRF-3(-/-) IRF-9(-/-) MEFs, which have blocked type I interferon signaling, did not increase HCV replication. Expression of liver-specific miR-122 in MEFs further stimulated the synthesis of HCV replicons in the rodent fibroblasts. The combined effects of miR-122 expression and deletion of IRF-3 produced a cooperative stimulation of HCV subgenome replication. miR-122 and IRF-3 are independent host factors that are capable of influencing HCV replication, and our findings could help to establish mouse models and other cell systems that support HCV growth and particle formation.
authors.affiliation: Department of Microbiology & Immunology, Dalhousie University, 5850 College St., Halifax, Nova Scotia, Canada B3H 1X5.
authors.forename: Liang-Tzung
authors.initials: LT
authors.lastname: Lin
authors.forename: Ryan S
authors.initials: RS
authors.lastname: Noyce
authors.forename: Tram N Q
authors.initials: TN
authors.lastname: Pham
authors.forename: Joyce A
authors.initials: JA
authors.lastname: Wilson
authors.forename: Gary R
authors.initials: GR
authors.lastname: Sisson
authors.forename: Thomas I
authors.initials: TI
authors.lastname: Michalak
authors.forename: Karen L
authors.initials: KL
authors.lastname: Mossman
authors.forename: Christopher D
authors.initials: CD
authors.lastname: Richardson
mesh_terms: D000818:Animals; D005347:Fibroblasts / Q000821:virology*; D016174:Hepacivirus / Q000276:immunology* / Q000502:physiology*; D050838:Interferon Regulatory Factor-3 / Q000172:deficiency* / Q000276:immunology; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit / Q000172:deficiency / Q000276:immunology; D051379:Mice; D018345:Mice, Knockout; D035683:MicroRNAs / Q000096:biosynthesis*; D017384:Sequence Deletion; D014779:Virus Replication
chemical_list: D050838:Interferon Regulatory Factor-3; D050834:Interferon-Stimulated Gene Factor 3, gamma Subunit; C494233:Irf3 protein, mouse; C494228:Isgf3g protein, mouse; D035683:MicroRNAs; C544354:Mirn122 microRNA, mouse