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The hepatitis C virus genotype is considered to be the most important baseline predictor of a sustained virological response in patients with chronic hepatitis C treated with pegylated interferon and ribavirin. The influence of the subtype on the sustained virological response was investigated in patients infected with genotypes 1, 4, 5, or 6. This study was done on 597 patients with chronic hepatitis C who were given pegylated interferon and ribavirin for 48 weeks. The overall rate of sustained virological response in the 597 patients was 37.8%. Univariate analysis indicated that the sustained virological response of patients infected with subtype 1b (39%) tended to be higher than that of patients infected with subtype 1a (30.6%; P = 0.06) and it was similar to those patients infected with subtypes 4a (51.3%; P = 0.12) or 4d (51.7%; P = 0.16). Multivariate analysis indicated that five factors were independently associated with sustained virological response: the age (OR 0.97; 95% CI = 0.95-0.99), absence of cirrhosis (OR: 2.92; 95% CI = 1.7-5.0; P < 0.01), absence of HIV co-infection (OR: 2.08; 95% CI = 1.2-3.5; P < 0.01), low baseline plasma HCV RNA concentration (OR: 1.74; 95% CI = 1.2-2.6; P < 0.01), and the subtype 1b (OR: 1.61; 95% CI = 1.0-2.5; P = 0.04) or subtypes 4a and 4d (OR: 2.03; 95% CI = 1.1-3.8; P = 0.03). In conclusion, among difficult-to-treat genotypes, the subtype 1a is associated with a lower response to anti-HCV therapy than subtypes 1b, 4a, and 4d., ((c) 2009 Wiley-Liss, Inc.)

Aim: To evaluate the implication of substitutions in the hepatitis C virus (HCV) non-structural 5A (NS5A) protein in the resistance of HCV during mono-interferon (IFN) or combined IFN-ribavirin (IFN-R) therapy. Although NS5A has been reported to interact with the HCV RNA-dependent RNA polymerase, NS5B, as well as with many cellular proteins, the function of NS5A in the life cycle of HCV remains unclear., Methods: HCV quasispecies were studied by cloning and sequencing of sequential isolates from patients infected by HCV genotype 1b. Patients were treated by IFN-alpha2b for 3 mo followed by IFN-alpha2b alone or combined IFN-R therapy for 9 additional months. Patients were categorized into two groups based on their response to the treatments: 7 with sustained virological response (SVR) (quasispecies = 150) and 3 non-responders (NR) to IFN-R (quasispecies = 106)., Results: Prior to treatment, SVR patients displayed a lower complexity of quasispecies than NR patients. Most patients had a decrease in the complexity of quasispecies during therapy. Analysis of amino acids substitutions showed that the degree of the complexity of the interferon sensitivity-determining region (ISDR) and the V3 domain of NS5A protein was able to discriminate the two groups of patients. Moreover, SVR patients displayed more variability in the NS5A region than NR patients., Conclusion: These results suggest that detailed molecular analysis of the NS5A region may be important for understanding its function in IFN response during HCV 1b infection.

The hepatitis C virus (HCV) envelope protein 2 (E2) interacts in vitro with the interferon alpha (IFN-alpha)-inducible double-stranded RNA-activated protein kinase, suggesting a possible mechanism by which HCV may evade the antiviral effects of IFN-alpha. Variability in the part of the HCV E2 gene encoding the carboxy-terminal part of the protein, which includes the interaction domain (E2-PePHD), was explored in 25 patients infected with HCV genotype 1b and receiving IFN-alpha therapy. PCR products were generated and sequenced for 15 patients with a sustained response and for 10 patients with no virological response after treatment with IFN-alpha and ribavirin. PePHD amino acid sequences were obtained for isolates from serum collected before and during treatment, after 2 months in responders, and after 6 months in nonresponders. Quasispecies analysis of the pretreatment PePHD region was performed for isolates from patients displaying amino acid substitutions in this domain on direct sequencing. The E2-PePHD sequence was highly conserved in both resistant and susceptible genotype 1b strains and was identical to the prototype HCV type J sequence. No significant emergence of PePHD mutants during therapy was observed in our clonal analysis, and sporadic mutations and treatment outcomes were not found to be correlated. The PePHD sequence before or during treatment cannot be used to predict reliably the outcome of treatment in HCV type 1b-infected patients.

Aim of the Study: The hepatitis C virus (HCV) non-structural NS5A protein has been controversially implicated in the resistance of HCV to interferon therapy in clinical studies. In Japan, mutations in the interferon sensitivity-determining region (ISDR) in the NS5A gene were associated with response to interferon therapy in patients infected with genotype 1b. In contrast, studies from Europe did not confirm such association. More recently, it has been suggested that the V3 domain outside the putative ISDR might also have amino acids changes that may be involved in the resistance to IFN. In this study, the relationship between NS5A mutations in ISDR and V3 domains and virological response to therapy were investigated., Materials and Methods: The NS5A gene was sequenced from 35 HCV genotype 1b infected patients at D0 of a prospective clinical trial of interferon therapy and interferon plus Ribavirin combination therapy., Results: In the ISDR domain, we did not observe any significant differences in amino acids changes between responders (1.7 +/- 1.8, n = 19, range 0-6) and non-responders (1.1 +/- 0.8, n = 14, range: 0-3), (P = 0.483), to therapy before the beginning of treatment. In the V3 domain, we found more mutations in responders (6.5 +/- 1.9, range: 2-11) than in non-responders (4.7 +/- 1.2, range: 3-8) (P = 0.0013), before the beginning of treatment., Conclusion: Our results confirm that, in Europe, the ISDR domain is not predictive for treatment success but suggest that the V3 domain have greater variability in responders than non-responders.