New antiviral pathway that mediates hepatitis C virus replicon interferon sensitivity through ADAR1.
While many clinical hepatitis C virus (HCV) infections are resistant to alpha interferon (IFN-alpha) therapy, subgenomic in vitro self-replicating HCV RNAs (HCV replicons) are characterized by marked IFN-alpha sensitivity. IFN-alpha treatment of replicon-containing cells results in a rapid loss of viral RNA via translation inhibition through double-stranded RNA-activated protein kinase (PKR) and also through a new pathway involving RNA editing by an adenosine deaminase that acts on double-stranded RNA (ADAR1). More than 200 genes are induced by IFN-alpha, and yet only a few are attributed with an antiviral role. We show that inhibition of both PKR and ADAR1 by the addition of adenovirus-associated RNA stimulates replicon expression and reduces the amount of inosine recovered from RNA in replicon cells. Small inhibitory RNA, specific for ADAR1, stimulated the replicon 40-fold, indicating that ADAR1 has a role in limiting replication of the viral RNA. This is the first report of ADAR's involvement in a potent antiviral pathway and its action to specifically eliminate HCV RNA through adenosine to inosine editing. These results may explain successful HCV replicon clearance by IFN-alpha in vitro and may provide a promising new therapeutic strategy for HCV as well as other viral infections.
Taylor
Deborah R
DR
CBER/FDA, HFM-448, 8800 Rockville Pike, Bethesda, MD 20892, USA. taylord@cber.fda.gov
Puig
Montserrat
M
Darnell
Miriam E R
ME
Mihalik
Kathleen
K
Feinstone
Stephen M
SM
D000241:Adenosine / Q000378:metabolism; D045744:Cell Line, Tumor; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D006526:Hepatitis C / Q000821:virology*; D006801:Humans; D007288:Inosine / Q000378:metabolism; D016898:Interferon-alpha / Q000494:pharmacology*; D017393:RNA Editing; D012367:RNA, Viral / Q000235:genetics; D012093:Replicon / Q000502:physiology*; D014779:Virus Replication / Q000276:immunology
D016898:Interferon-alpha; D012367:RNA, Viral; D007288:Inosine; D000241:Adenosine