Sequence variation in hepatitis C virus nonstructural protein 5A predicts clinical outcome of pegylated interferon/ribavirin combination therapy.
A substantial proportion of hepatitis C virus (HCV)-1b-infected patients still do not respond to interferon-based therapy. This study aims to explore a predictive marker for the ultimate virological response of HCV-1b-infected patients treated with pegylated interferon/ribavirin (PEG-IFN/RBV) combination therapy. Nonstructural protein 5A (NS5A) sequences of HCV in the pretreated sera of 45 patients infected with HCV-1b were analyzed. The mean number of mutations in the variable region 3 (V3) plus its upstream flanking region of NS5A (amino acid 2334-2379), referred to as IFN/RBV resistance-determining region (IRRDR), was significantly higher for HCV isolates obtained from patients who later achieved sustained virological response (SVR) by PEG-IFN/RBV than for those in patients undergoing non-SVR. The receiver operating characteristic curve analysis estimated six mutations in IRRDR as the optimal threshold for SVR prediction. Indeed, 16 (76%) of 21 SVR, but only 2 (8%) of 24 non-SVR, had HCV with six or more mutations in IRRDR (IRRDR > or = 6) (P < 0.0001). All of 18 patients infected with HCV of IRRDR of 6 or greater examined showed a significant (> or =1 log) reduction or disappearance of serum HCV core antigen titers within 24 hours after initial dose of PEG-IFN/RBV, whereas 10 (37%) of 27 patients with HCV of IRRDR of 5 or less did (P < 0.0001). The positive predictive value of IRRDR of 6 or greater for SVR was 89% (16/18; P = 0.0007), with its negative predictive value for non-SVR being 81% (22/27; P = 0.0008).


CONCLUSIONS
A high degree (> or =6) of sequence variation in IRRDR would be a useful marker for predicting SVR, whereas a less diverse (< or =5) IRRDR sequence predicts non-SVR.
Division of Microbiology, Kobe University Graduate School of Medicine, Kobe, Japan.
Ahmed
A
El-Shamy
Motoko
M
Nagano-Fujii
Noriko
N
Sasase
Susumu
S
Imoto
Soo-Ryang
SR
Kim
Hak
H
Hotta
D000368:Aged; D000998:Antiviral Agents / Q000627:therapeutic use*; D016384:Consensus Sequence; D004359:Drug Therapy, Combination; D005260:Female; D014644:Genetic Variation; D005838:Genotype; D016174:Hepacivirus / Q000187:drug effects / Q000235:genetics; D019698:Hepatitis C, Chronic / Q000188:drug therapy*; D006801:Humans; D000077190:Interferon alpha-2; D016898:Interferon-alpha / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011092:Polyethylene Glycols; D011237:Predictive Value of Tests; D011994:Recombinant Proteins; D012254:Ribavirin / Q000627:therapeutic use*; D016896:Treatment Outcome; D017361:Viral Nonstructural Proteins / Q000235:genetics*; D012324:RNA-Dependent RNA Polymerase
D000998:Antiviral Agents; D000077190:Interferon alpha-2; D016898:Interferon-alpha; D011092:Polyethylene Glycols; D011994:Recombinant Proteins; D012254:Ribavirin; D017361:Viral Nonstructural Proteins; C087036:NS-5 protein, hepatitis C virus; D012324:RNA-Dependent RNA Polymerase; C417083:peginterferon alfa-2b