Expression of hepatitis C virus NS5A natural mutants in a hepatocytic cell line inhibits the antiviral effect of interferon in a PKR-independent manner.
The impact of hepatitis C virus NS5A protein mutations on interferon alfa (IFN-alpha) signaling pathway, cell proliferation, and viability is an important issue that is still under debate. We have therefore combined transient and stable expression in a human hepatocytic cell line (Huh7) of 3 full-length NS5A sequences, isolated from patients with or without response to IFN-alpha therapy. Expression of all 3 NS5A-reduced IFN-alpha global antiviral activity on both vesicular stomatitis virus (VSV) and encephalomyocarditis virus (EMCV) replication. We did not show, however, an effect of these 3 NS5A proteins on double-stranded RNA-dependent kinase (PKR) expression and activity as well as colocalization and coimmunoprecipitation between NS5A and PKR. We also failed to show an effect of the 3 NS5A mutants tested on cell proliferation and viability. Overall, our results support an important role of NS5A in controlling IFN-alpha antiviral activity; they show, however, that PKR-independent mechanisms are implicated, at least in liver-derived cells.
Podevin
P
P
INSERM U370, Necker Institute, Paris, France.
Sabile
A
A
Gajardo
R
R
Delhem
N
N
Abadie
A
A
Lozach
P Y
PY
Beretta
L
L
Bréchot
C
C
D015088:2',5'-Oligoadenylate Synthetase / Q000235:genetics; D016475:3T3 Cells; D000595:Amino Acid Sequence / Q000235:genetics; D000818:Animals; D000998:Antiviral Agents / Q000037:antagonists & inhibitors*; D002455:Cell Division / Q000502:physiology; D002460:Cell Line; D002470:Cell Survival / Q000502:physiology; D019204:GTP-Binding Proteins; D015870:Gene Expression; D022781:Hepatocytes / Q000502:physiology*; D006801:Humans; D016898:Interferon-alpha / Q000037:antagonists & inhibitors*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics*; D064547:Myxovirus Resistance Proteins; D011233:Precipitin Tests; D011506:Proteins / Q000235:genetics; D051381:Rats; D014018:Tissue Distribution; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism*; D019892:eIF-2 Kinase / Q000235:genetics / Q000502:physiology*; D012324:RNA-Dependent RNA Polymerase
D015088:2',5'-Oligoadenylate Synthetase; D000998:Antiviral Agents; D019204:GTP-Binding Proteins; D016898:Interferon-alpha; D064547:Myxovirus Resistance Proteins; D011506:Proteins; D017361:Viral Nonstructural Proteins; D019892:eIF-2 Kinase; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase