Mutations in the E2-PePHD and NS5A region of hepatitis C virus type 1 and the dynamics of hepatitis C viremia decline during interferon alfa treatment.
Both a double-stranded RNA-dependent protein kinase (PKR)-phosphorylation homology domain (PePHD) within the E2 protein and a PKR-binding domain within the nonstructural 5A (NS5A) protein of hepatitis C virus (HCV) genotype 1 isolates inhibit the function of the interferon alfa (IFN-alpha)-induced antiviral effector protein PKR in vitro. We investigated whether the mutational pattern of the E2 region (codons 618-681, including PePHD) of 81 HCV genotype 1-infected patients (HCV-1b [n = 54], HCV-1a [n = 27]) influences the response to IFN-alpha. Initial viral decline (DeltaHCV RNA) was determined at week 1 hereby covering the effector reactions of IFN-alpha-mediated first phase and the immune-mediated second phase. DeltaHCV RNA less than 50% (group 1); DeltaHCV RNA greater than 50% but less than 90% (group 2); and DeltaHCV RNA > or =90% (group 3) were differentiated. The PePHD region was highly conserved; the few mutations (5 patients) did not correlate with DeltaHCV RNA or sustained virologic response to IFN-alpha. Within the flanking regions before and after PePHD (codons 618-681) 72 of 81 patients (89%) had 2.6+/-0.17 mutations (median, 3; range, 1-8) that did not correlate with treatment response. Sequence analysis of the NS5A protein (codons 2,209-2,274, including interferon sensitivity determining region [ISDR]) in 39 of 81 patients showed a higher mean number of mutations in the ISDR (codons 2,209-2,248) in groups 2 (1.28+/- 0.43 [n = 18]) and 3 (1.89+/-0.54 [n = 9]) than in group 1 (0.67+/- 0.19 [n = 12]; P =.049 group 1 vs. 3) and a mutant type ISDR (e.g., > or =4 mutations) was significantly more frequent in sustained virologic responders than in nonresponders or relapsers (2 of 4 [50%] vs. 2 of 35 [6%]; P =.045). Thus, NS5A appears to be functionally relevant in IFN-alpha-induced effector reactions.
Berg
T
T
Medizinische Klinik mit Schwerpunkt Hepatologie und Gastroenterologie, Universitätsklinikum Charité, Campus Virchow-Klinikum, Humboldt-Universität, Berlin, Germany. thomas.berg@charite.de
Mas Marques
A
A
Höhne
M
M
Wiedenmann
B
B
Hopf
U
U
Schreier
E
E
D000595:Amino Acid Sequence / Q000235:genetics; D000998:Antiviral Agents / Q000627:therapeutic use*; D005260:Female; D005787:Gene Frequency; D016174:Hepacivirus / Q000235:genetics* / Q000302:isolation & purification; D006526:Hepatitis C / Q000188:drug therapy* / Q000821:virology; D006801:Humans; D016898:Interferon-alpha / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation / Q000235:genetics*; D010446:Peptide Fragments / Q000235:genetics; D010802:Phylogeny; D017433:Protein Structure, Secondary; D013997:Time Factors; D014759:Viral Envelope Proteins / Q000235:genetics*; D017361:Viral Nonstructural Proteins / Q000235:genetics* / Q000378:metabolism; D014766:Viremia / Q000821:virology*; D019892:eIF-2 Kinase / Q000378:metabolism; D012324:RNA-Dependent RNA Polymerase
D000998:Antiviral Agents; D016898:Interferon-alpha; D010446:Peptide Fragments; D014759:Viral Envelope Proteins; D017361:Viral Nonstructural Proteins; D019892:eIF-2 Kinase; C091015:glycoprotein E2, Hepatitis C virus; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase