Lack of clinical evidence for involvement of hepatitis C virus interferon-alpha sensitivity-determining region variability in RNA-dependent protein kinase-mediated cellular antiviral responses.
The hepatitis C virus (HCV) interferon-alpha (IFN-alpha) sensitivity-determining region (ISDR) has been shown to suppress double-stranded RNA-dependent protein kinase (PKR) activity in vitro in a yeast PKR expression system. Since variability of ISDR was shown to correlate with nonresponsiveness to IFN-alpha therapy in chronically HCV-infected patients, it has been suggested that prototype ISDR might be a viral inhibitor of cellular PKR. The present study evaluates the biological significance of ISDR variability in situ, relating it to PKR-mediated cellular antiviral responses within the liver. ISDR variability was determined in patients chronically infected with HCV genotypes 1a, 1b, and 3a by direct sequencing using liver-derived RNA preparations as starting material. As surrogate parameters for PKR-mediated cellular responses, hepatic endogenous IFN-alpha gene expression as well as MxA expression were analysed by a competitive, quantitative reverse transcription-polymerase chain reaction technique. Irrespectively of intra- or intergenotypic ISDR amino acid substitutions, ISDR variability was found not to correlate with endogenous hepatic IFN-alpha or with hepatic MxA gene expression. The data suggest that at least two prominent PKR-mediated cellular responses might be largely unaffected by HCV ISDR variability.
Mihm
S
S
Department of Internal Medicine, Georg-August-Universität, Göttingen, Germany. smihm@med.uni-goettingen.de
Monazahian
M
M
Grethe
S
S
Meier
V
V
Thomssen
R
R
Ramadori
G
G
D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000998:Antiviral Agents / Q000235:genetics / Q000378:metabolism; D005260:Female; D019204:GTP-Binding Proteins; D015967:Gene Expression Regulation, Viral; D014644:Genetic Variation; D016174:Hepacivirus / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D019698:Hepatitis C, Chronic / Q000378:metabolism / Q000821:virology*; D006801:Humans; D016898:Interferon-alpha / Q000235:genetics* / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D064547:Myxovirus Resistance Proteins; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D020539:Sequence Analysis, Protein; D019892:eIF-2 Kinase / Q000378:metabolism*
D000998:Antiviral Agents; D016898:Interferon-alpha; C579071:MX1 protein, human; D064547:Myxovirus Resistance Proteins; D011506:Proteins; D019892:eIF-2 Kinase; D019204:GTP-Binding Proteins