Hepatitis C Virus Genotype 1b-infected Patients Research Articles

NS5A Gene Analysis by Next Generation Sequencing in HCV Nosocomial Transmission Clusters of HCV Genotype 1b Infected Patients.

Background: The aim of the study was to investigate the intra-host variability through next-generation-sequencing (NGS) of the NS5A-gene in nosocomial transmission-clusters observed in two Italian hospitals among hepatitis C virus (HCV)-genotype-1b infected patients. Methods: HCV-sequencing was performed by Sanger-sequencing (NS3 + NS5A + NS5B) and by NGS (NS5A, MiSeq-Illumina) in 15 HCV-1b infected patients [five acute with onco-hematologic-disease and 10 (4/6 acute/chronic) with β-thalassemia]. Resistance-associated-substitutions (RAS) were analysed by Geno2pheno-algorithm. Nucleotide-sequence-variability (NSV, at 1%, 2%, 5%, 10% and 15% NGS-cutoffs) and Shannon entropy were estimated. Phylogenetic analysis was performed by Mega6-software and Bayesian-analysis. Results: Phylogenetic analysis showed five transmission-clusters: one involving four HCV-acute onco-hematologic-patients; one involving three HCV-chronic β-thalassemia-patients and three involving both HCV-acute and chronic β-thalassemia-patients. The NS5A-RAS Y93H was found in seven patients, distributed differently among chronic/acute patients involved in the same transmission-clusters, independently from the host-genetic IL-28-polymorphism. The intra-host NSV was higher in chronic-patients versus acute-patients, at all cutoffs analyzed (p < 0.05). Even though Shannon-entropy was higher in chronic-patients, significantly higher values were observed only in chronic β-thalassemia-patients versus acute β-thalassemia-patients (p = 0.01). Conclusions: In nosocomial HCV transmission-clusters, the intra-host HCV quasispecies divergence in patients with acute-infection was very low in comparison to that in chronic-infection. The NS5A-RAS Y93H was often transmitted and distributed differently within the same transmission-clusters, independently from the IL-28-polymorphism.

Efficacy of direct-acting antiviral treatment in patients with compensated liver cirrhosis: A multicenter study.

Although the development of new direct-acting antivirals (DAAs) for the treatment of chronic hepatitis C virus (HCV) infection has markedly advanced, the effects of cirrhosis on DAA treatment remain unclear. We aimed to clarify the impact of cirrhosis on DAA treatment of patients infected with HCV. This large-scale, multicenter, retrospective study consisted of 2130 HCV genotype 1b-infected patients who were treated with one of the following DAA combination therapies: asunaprevir/daclatasvir (ASV/DCV), ledipasvir/sofosbuvir (LDV/SOF), or paritaprevir/ombitasvir/ritonavir (PTV/OBV/r). Ninety-two patients (4.3%) previously received DAA-based treatment. Seven hundred and forty-five patients (34.9%) had cirrhosis. Overall, the sustained virologic response (SVR) rate was 93.0%. The SVR rates in patients who received ASV/DCV, LDV/SOF, or PTV/OBV/r were 90.0%, 96.9%, and 97.6%, respectively. The SVR rate in patients with cirrhosis (89.1%) was significantly lower than that in patients without cirrhosis (95.1%, P = 6.94 × 10-7 ). In the multivariate analysis for the overall cohort, absence of cirrhosis (P = 1.26 × 10-3 ), no previous DAA-based treatment (P = 2.54 × 10-14 ), low HCV-RNA levels (P = 1.64 × 10-6 ), wild-type non-structural protein 5A L31/Y93 (P = 7.33 × 10-13 ), and DAA regimen (LDV/SOF or PTV/OBV/r) (P = 1.92 × 10-14 ) were independent factors contributing to SVR. Except for patients with DAA-based treatment history, absence of cirrhosis (P = 2.15 × 10-3 ; odds ratio, 2.51) was an independent factor contributing to SVR in 2038 DAA-naïve patients. This study suggests that the presence of cirrhosis reduces the SVR rate of DAA treatment, regardless of the type of DAA treatment.

Baseline Intrahepatic and Peripheral Innate Immunity are Associated with Hepatitis C Virus Clearance During Direct-Acting Antiviral Therapy.

Hepatitis C virus (HCV) infection induces interferon (IFN)-stimulated genes (ISGs) and downstream innate immune responses. This study investigated whether baseline and on-treatment differences in these responses predict response versus virological breakthrough during therapy with direct-acting antivirals (DAAs). Thirteen HCV genotype 1b-infected patients who had previously failed a course of pegylated IFN/ribavirin were retreated with asunaprevir/daclatasvir for 24 weeks. After pretreatment biopsy, patients were randomized to undergo a second biopsy at week 2 or 4 on therapy. Microarray and NanoString analyses were performed on paired liver biopsies and analyzed using linear mixed models. As biomarkers for peripheral IFN responses, peripheral blood natural killer cells were assessed for phosphorylated signal transducer and activator of transcription 1 (pSTAT1) and tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) expression and degranulation. Nine of 13 (69%) patients achieved sustained virological response at 12 weeks off therapy (SVR12), and 4 experienced virological breakthroughs between weeks 4 and 12. Patients who achieved SVR12 displayed higher ISG expression levels in baseline liver biopsies and a higher frequency of pSTAT1 and TRAIL-expressing, degranulating natural killer cells in baseline blood samples than those who experienced virological breakthrough. Comparing gene expression levels from baseline and on-therapy biopsies, 408 genes (±1.2-fold, P < 0.01) were differentially expressed. Genes down-regulated on treatment were predominantly ISGs. Down-regulation of ISGs was rapid and correlated with HCV RNA suppression. Conclusion: An enhanced IFN signature is observed at baseline in liver and blood of patients who achieve SVR12 compared to those who experience a virological breakthrough; the findings suggest that innate immunity may contribute to clearance of HCV during DAA therapy by preventing the emergence of resistance-associated substitutions that lead to viral breakthrough during DAA therapy.

Daclatasvir and asunaprevir combination therapy for patients with chronic hepatitis C virus genotype 1b infection in real world.

Background/AimsPrevious studies have reported a high rate of sustained virologic response (SVR) and a low rate of serious adverse events with the use of daclatasvir (DCV) and asunaprevir (ASV) combination therapy. We evaluated the efficacy and safety of DCV and ASV combination therapy for patients with chronic hepatitis C virus (HCV) genotype 1b infection in real world.MethodsWe enrolled 278 patients (184 treatment-naïve patients) from five hospitals in Daegu and Gyeongsangbuk-do. We evaluated the rates of rapid virologic response (RVR), end-of-treatment response (ETR), and SVR at 12 weeks after completion of treatment (SVR12). Furthermore, we investigated the rate of adverse events and predictive factors of SVR12 failure.ResultsThe mean age of patients was 59.5 ± 10.6 years, and 140 patients (50.2%) were men. Seventy-seven patients had cirrhosis. Baseline information regarding nonstructural protein 5A (NS5A) sequences was available in 268 patients. Six patients presented with pretreatment NS5A resistance-associated variants. The RVR and the ETR rates were 96.6% (258/267) and 95.2% (223/232), respectively. The overall SVR12 rate was 91.6% (197/215). Adverse events occurred in 17 patients (7.9%). Six patients discontinued treatment because of liver enzyme elevation (n = 4) and severe nausea (n = 2). Among these, four achieved SVR12. Other adverse events observed were fatigue, headache, diarrhea, dizziness, loss of appetite, skin rash, and dyspnea. Univariate analysis did not show significant predictive factors of SVR12 failure.ConclusionsDCV and ASV combination therapy showed high rates of RVR, ETR, and SVR12 in chronic HCV genotype 1b-infected patients in real world and was well tolerated without serious adverse events.

Prevalence of hepatitis C virus-resistant association substitutions to direct-acting antiviral agents in treatment-naïve hepatitis C genotype 1b-infected patients in western China.

BackgroundDirect-acting antivirals (DAAs) against hepatitis C virus (HCV) are potent and highly efficacious. However, resistance-associated substitutions (RASs) relevant to DAAs can impair treatment effectiveness even at baseline. Moreover, the prevalence of baseline RASs in HCV genotype 1b-infected patients in western China is still unclear.Materials and methodsDirect sequencing of the HCV NS3, NS5A, and NS5B regions was performed in baseline serum samples of 70 DAAs treatment-naïve HCV 1b-infected patients in western China. The sequences were analyzed with MEGA version 5.05 software. Evolutionary patterns of RASs and amino-acid covariance patterns in the NS3, NS5A, and NS5B genes were analyzed by MEGA and Cytoscape (version 3.2.1), respectively.ResultsThe presence of at least one RAS in the NS3 region (C16S, T54S, Q80R/L, A87T, R117H, S122G, V132I, V170I) was observed in 85.48% (53 of 62) of patients, RASs in the NS5A region (L28M, R30Q, Q54H, P58S/T, Q62H/R, Y93H) were observed in 42.42% (28 of 66) of patients, and RASs in the NS5B region (N142S, A300T, C316N, A338V, S365A, L392I, M414L, I424V, A442T, V499A, S556G) were observed in 100% (44 of 44) of patients. Evolutionary patterns of RASs and amino-acid covariance patterns for the NS3, NS5A, and NS5B genes are reported.ConclusionThe prevalence of RASs relevant to DAAs detected in the NS3, NS5A, and NS5B regions of HCV 1b from DAA treatment-naïve patients is high. Therefore, more attention should be paid to RASs associated with DAAs in the upcoming DAA-treatment era in China.

Add-on effects of fluvastatin in simeprevir/pegylated-interferon/ribavirin combination therapy for patients with genotype 1 hepatitis C virus infection: A randomized controlled study.

The Japan Society of Hepatology guidelines indicate that hepatitis C virus (HCV) protease inhibitor combination therapy with simeprevir (SMV), pegylated-interferon (Peg-IFN), and ribavirin (RBV) is a therapeutic option for patients who fail to respond to a direct direct-acting antiviral-containing regimen. However, treatment outcomes have room for improvement. Fluvastatin (FLV) add-on treatment in Peg-IFN and RBV combination therapy for HCV-infected patients significantly improved the sustained virologic response (SVR), but the add-on effect of FLV on SMV combination therapy is not well understood. This was a prospective, randomized, multicenter study in which a total of 61 HCV genotype 1b-infected patients were recruited and 60 eligible patients were randomly allocated to two groups that received 12weeks of SMV/Peg-IFN/RBV followed by 12weeks of Peg-IFN/RBV with or without 24weeks of FLV. The SVR rate and adverse events were compared between the two groups. Thirty-one patients were allocated to the FLV add-on group and 29 patients were allocated to the control group. Baseline clinical factors, including median age, baseline platelet count, alanine aminotransferase level, HCV RNA titer, Fibrosis-4 index, and rate of IL28B minor genotype, were all similar between the two groups. The rapid virologic response, end-of-treatment response rates, SVR rates at 24weeks after treatment, and safety profiles were also similar between the two groups. This prospective, randomized, multicenter study indicated that FLV had no add-on effect when given with SMV/Peg-IFN/RBV combination therapy for genotype 1b HCV-infected patients.

Naturally occurring drug resistance associated variants to hepatitis C virus direct-acting antiviral agents in treatment-naive HCV genotype 1b-infected patients in China.

The direct-acting antiviral agents (DAAs) have drastically improved the prognosis of hepatitis C virus (HCV) patients. However, the resistance-associated variants (RAVs) to DAAs may hamper treatment. There was a lack of data on the prevalence of pre-exist RAVs in Chinese HCV-infected patients. We performed nested PCR assays on 74 HCV genotype 1b-infected patients to amplify HCV viral regions of NS3, NS5A, and NS5B to investigate the prevalence of RAVs to DAAs in treatment-naive HCV genotype1b-infected patients in China. The mutations A156S, T54S, and D168Y of the NS3/4A region were found in 18.33% (11/60), 6.67% (4/60), and 1.67% (1/60) of the successfully amplified cases. Mutations Q30R, L31M, and H58P of the NS5A region were confirmed in 57.63% (34/59), 1.69%(1/59), and 86.44% (51/59) of the cases. Mutations C316N, S365A, M414L, M423I, Y448H, I482T, I482 V, V494L, P495S, and V499A of the NS5B region were detected in 100% (60/60), 3.33% (2/60), 5.88% (3/51), 1.96% (1/51), 1.96% (1/51), 5.88% (3/51), 1.96% (1/51), 3.92% (2/51), 5.88% (3/51), and 15.69% (8/51) of cases, respectively. Naturally occurring RAVs to DAAs pre-exist in treatment-naive Chinese HCV genotype 1b-infected patients and the characteristic is different from that in Europe and the United States. Clinicians should consider RAVs upon the introduction of DAA-based antiviral therapy.

Sustained virologic response of 100% in HCV genotype 1b patients with cirrhosis receiving ombitasvir/paritaprevir/r and dasabuvir for 12 weeks

Patients with chronic hepatitis C virus (HCV) infection and cirrhosis have a higher risk for liver-related complications and have historically been more difficult to cure than patients without cirrhosis. We evaluated the safety and efficacy of ombitasvir/paritaprevir/ritonavir and dasabuvir, without ribavirin, for 12weeks in patients with HCV genotype 1b infection and compensated cirrhosis. Treatment-naïve and peginterferon/ribavirin treatment-experienced patients received 12weeks of ombitasvir/paritaprevir/ritonavir (25/150/100mg once daily) and dasabuvir (250mgtwicedaily). Key inclusion criteria were hemoglobin ⩾10g/dl, albumin ⩾2.8g/dl, platelet count ⩾25×10(9)/L, creatinine clearance ⩾30ml/min, and Child-Pugh score ⩽6. Efficacy was assessed by the percentage of patients achieving SVR (HCV RNA <25IU/ml) 12weeks post-treatment (SVR12). Efficacy and safety were assessed in all patients receiving study drug. Sixty patients with HCV genotype 1b infection and cirrhosis received treatment. The study population comprised 62% male, 55% treatment-experienced, 83% with IL28B non-CC genotype, 22% with platelet count <90×10(9)/L, and 17% with albumin <3.5g/dl. All 60 patients completed treatment, and SVR12 was achieved in 100% (95% CI, 94.0-100%) of patients. The most common adverse events were fatigue (22%), diarrhea (20%), and headache (18%). Only one patient (1.7%) experienced a serious adverse event. Laboratory abnormalities were infrequently observed and not clinically significant. The HCV regimen of ombitasvir/paritaprevir/ritonavir and dasabuvir without ribavirin for 12weeks achieved 100% SVR12 and was well tolerated in HCV genotype 1b-infected patients with cirrhosis, suggesting that this 12-week ribavirin-free regimen is sufficient in this population.

Effect of Hepatitis C Virus Genotype 1b Core and NS5A Mutations on Response to Peginterferon Plus Ribavirin Combination Therapy.

We examined whether hepatitis C virus (HCV) genotype 1b core- and NS5A-region mutations are associated with response to peginterferon α-2b plus ribavirin combination therapy. A total of 103 patients with high HCV genotype 1b viral loads (≥100 KIU/mL) were treated with the combination therapy. Pretreatment mutations in the core region and interferon sensitivity determining region (ISDR) in the NS5A region were analyzed. In univariate analysis, arginine and leucine at positions 70 and 91 in the core region, defined as double wild (DW)-type, were associated with early virologic response (p = 0.002), sustained virologic response (SVR) (p = 0.004), and non-response (p = 0.005). Non-threonine at position 110 was associated with SVR (p = 0.004). Multivariate analysis showed the following pretreatment predictors of SVR: hemoglobin level ≥ 14 g/dL (odds ratio (OR) 6.2, p = 0.04); platelet count ≥ 14 × 104/mm3 (OR 5.2, p = 0.04); aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio < 0.9 (OR 6.17, p = 0.009); DW-type (OR 6.8, p = 0.02); non-threonine at position 110 (OR 14.5, p = 0.03); and ≥2 mutations in the ISDR (OR 12.3, p = 0.02). Patients with non-DW-type, non-threonine at position 110, and <2 ISDR mutations showed significantly lower SVR rates than others (11/45 (24.4%) vs. 27/37 (73.0%), respectively; p < 0.001). SVR can be predicted through core and NS5A region mutations and host factors like hemoglobin, platelet count, and AST/ALT ratio in HCV genotype 1b-infected patients treated with peginterferon and ribavirin combination therapy.

HCV NS5A resistance-associated variants in a group of real-world Japanese patients chronically infected with HCV genotype 1b.

Recent advances in interferon-free treatment could lead to the eradication of hepatitis C virus (HCV) from patients infected with HCV. One of the direct-acting anti-viral agents, HCV NS5A inhibitor, is available for these combination therapies. However, naturally occurring resistance-associated variants (RAVs) to HCV NS5A inhibitors in treatment-naïve patients chronically infected with HCV genotype 1b are still unknown. We performed ultra-deep sequencing and analysed previously reported RAVs in a total 132 HCV genotype 1b-infected Japanese patients who had never used HCV NS5A inhibitors. We also performed direct-sequencing by Sanger method in consecutively selected 50 of the total 132 samples, and the differences between the results of the two methods were compared. In the comparison of the variant frequencies of ultra-deep sequencing with RAVs of direct-sequencing by Sanger method in 50 patients, we identified 32 RAVs by direct-sequencing with the Sanger method; minimum variant frequency was shown by ultra-deep sequencing to be 9%. A total of 110 RAVs were identified only by ultra-deep sequencing. In the samples from all 132 patients, L31W (2.3%), L31V (49.2%), L31F (41.7%), L31M (1.5%), L31I (5.3%), L31S (2.0%), L31P (3.0%) and L31R (0.8%), and Y93N (2.3%), Y93H (25%), Y93C (0.8%), Y93P (2.3%) and Y93D (0.8%) were identified. We demonstrated naturally-occurring RAVs of HCV NS5A inhibitors by ultra-deep sequencing and that several mutations including Y93H are common in HCV NS5A inhibitor-treatment-naïve patients with chronic HCV genotype 1b. Careful attention should be paid to these RAVs, and further improvement of treatment options might be needed.

Is the use of IL28B genotype justified in the era of interferon-free treatments for hepatitis C?

In 2009, several groups reported that interleukin-28B (IL28B) genotypes are associated with the response to peginterferon plus ribavirin therapy for chronic hepatitis C virus (HCV) infection in a genome-wide association study, although the mechanism of this association is not yet well understood. However, in recent years, tremendous progress has been made in the treatment of HCV infection. In Japan, some patients infected with HCV have the IL28B major genotype, which may indicate a favorable response to interferon-including regimens; however, certain patients within this group are also interferon-intolerant or ineligible. In Japan, interferon-free 24-wk regimens of asunaprevir and daclatasvir are now available for HCV genotype 1b-infected patients who are interferon-intolerant or ineligible or previous treatment null-responders. The treatment response to interferon-free regimens appears better, regardless of IL28B genotype. Maybe other interferon-free regimens will widely be available soon. In conclusion, although some HCV-infected individuals have IL28B favorable alleles, importance of IL28B will be reduced with availability of oral interferon free regimen.

In Vitro Assessment of Re-treatment Options for Patients with Hepatitis C Virus Genotype 1b Infection Resistant to Daclatasvir Plus Asunaprevir.

IntroductionDaclatasvir is a non-structural protein 5A (NS5A) inhibitor with activity against hepatitis C virus (HCV) genotypes 1–6 in vitro, and asunaprevir is a non-structural protein 3 (NS3) protease inhibitor with activity against genotypes 1, 4, 5, and 6. This study evaluates potential options for the re-treatment of HCV genotype 1b-infected patients who have failed combination therapy with daclatasvir plus asunaprevir.MethodsThe antiviral activity of drug combination regimens in HCV subgenomic replicon cell lines representing genotype 1b (Con1 strain) wild-type or a variant with specific NS5A and NS3 amino acid substitutions conferring resistance to daclatasvir and asunaprevir were compared using replicon elimination assays. Drug concentrations representing multiple 50% effective concentrations (EC50) derived in vitro and trough plasma concentrations observed in a clinical setting were utilized.ResultsAt multiple EC50 values of each drug (3×, 10×, and 30× EC50), combinations of daclatasvir plus sofosbuvir, sofosbuvir plus ledipasvir, sofosbuvir plus simeprevir, and sofosbuvir plus either a next-generation NS3 or NS5A inhibitor demonstrated comparable activity in wild-type and daclatasvir/asunaprevir-resistant cell lines. At clinically relevant drug trough concentrations, combination regimens of daclatasvir plus asunaprevir plus beclabuvir (±ribavirin), and daclatasvir plus asunaprevir plus beclabuvir plus sofosbuvir efficiently cleared daclatasvir + asunaprevir-resistant replicons from cells within 5 days of treatment.ConclusionOur in vitro results highlight a number of potential all-oral treatment options for patients who do not achieve a sustained virologic response following therapy with daclatasvir plus asunaprevir. These results require further evaluation in clinical studies.Electronic supplementary materialThe online version of this article (doi:10.1007/s40121-014-0052-8) contains supplementary material, which is available to authorized users.

Characterization of naturally occurring protease inhibitor-resistance mutations in genotype 1b hepatitis C virus patients

Protease inhibitor (PI)-resistant hepatitis C virus (HCV) variants may be present in substantial numbers in PI-untreated patients according to recent reports. However, influence of these viruses in the clinical course of chronic hepatitis C has not been well characterized. The dominant HCV nonstructural 3 (NS3) amino acid sequences were determined in 261 HCV genotype 1b-infected Japanese patients before pegylated interferon plus ribavirin (PEG-IFN/RBV) therapy, and investigated the patients' clinical characteristics as well as treatment responses including sustained virological response (SVR) rate. HCV-NS3 sequences were also determined in 39 non-SVR patients after completion of the therapy. Four single mutations (T54S, Q80K, I153V, and D168E) known to confer PI resistance were found in 35 of 261 patients (13.4%), and double mutations (I153V plus T54S/D168E) were found in 6 patients (2.3%). Responses to PEG-IFN/RBV therapy did not differ between patients with and without PI-resistance mutations (mutation group, SVR 48%; wild-type group, SVR 40%; P=0.38). On the other hand, two mutations appeared in two non-SVR patients after PEG-IFN/RBV therapy (I153V and E168D, 5.1%). PI-resistance-associated NS3 mutations exist in a substantial proportion of untreated HCV-1b-infected patients. The impact of these mutations in the treatment of PIs is unclear, but clinicians should pay attention to avoid further development of PI resistance.

Investigation of Interferon-α Response by a Single Amino Acid Substitution of Nonstructural Protein 5A in Hepatitis C Virus-Infected Patients

The therapeutic efficacy of interferon (IFN) for the hepatitis C is closely related with mutations in interferon sensitivity determining region or V3 domain of the hepatitis C virus (HCV) nonstructural protein 5A (NS5A). However, the relationship between alanine aminotransferase (ALT) normalization and the NS5A variability remains unclear. To clarify these features of NS5A, we examined the genetic variability of the patients' NS5A from 33 HCV genotype 1b-infected patients: 11 sustained virological response (SVR), 11 end-of-treatment response (ETR) with normal ALT (<40 IU/L), and 11 non-response (NR) with abnormal ALT (>40 IU/L) after IFN treatment for >24 weeks. The amino acid in position 2378 (followed by HCV-J prototype strain) with alanine (A2378) before IFN treatment was frequent in both SVR and ETR after IFN treatment, whereas that with threonine (T2378) was significant in NR. Moreover, substitution of threonine for alanine in HCV subgenomic replicon showed a 3- to 4-fold reduction of IFN transactivation and replication even in the presence of IFN, suggesting an IFN-resistant phenotype. These observations suggest that a single amino acid in position 2378 of NS5A plays important roles for both ALT normalization and IFN response in HCV-1b infected patients.

Mutations in ISDR of NS5A gene influence interferon efficacy in Chinese patients with chronic hepatitis C virus genotype 1b infection

The interferon sensitivity determining region (ISDR) in the non-structural 5A protein (NS5A) gene of hepatitis C virus genotype 1b (HCV-1b) has been demonstrated in Japanese patients; however, contradictory data have been reported from other parts of the world, particularly from Europe and the USA. This study investigated whether mutations in the ISDR of NS5A gene influence interferon efficacy in Chinese patients with chronic HCV-1b infection. Forty-five Chinese patients with chronic HCV infection were enrolled in a retrospective study. Of these patients, 20 with HCV-1b infection completed an interferon monotherapy course and 6-month follow-up. The pretreatment mutations in the nucleic acid sequence of NS5A 2209-2248 (ISDR) of HCV-1b were identified by sequencing RT-PCR products followed by comparison with the prototype sequence (HCV-J). Correlation with the clinical efficacy of interferon alpha therapy was then analyzed retrospectively. The statistical analysis indicated a significant correlation between the mutations in ISDR of HCV-1b and sustained virological response to interferon alpha treatment (P < 0.05), and an association of the mutations in ISDR with the pretreatment serum alanine aminotransferase levels (P < 0.01) in Chinese patients with chronic HCV-1b infection. The results support the concept that the response of HCV-1b infected patients towards interferon therapy is influenced by the mutations within the ISDR of NS5A gene.

Analyse des mutations des domaines ISDR et V3 de la protéine NS5A du virus de l'hépatite C avant le traitement par l'interféron avec ou sans ribavirine

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.

The prognostic relevance of the nonstructural 5A gene interferon sensitivity determining region is different in infections with genotype 1b and 3a isolates of hepatitis C virus.

Hepatitis C virus (HCV) RNA serum concentration, quasispecies complexity, and sequence and phylogenetic analysis of the nonstructural 5A gene (NS5A) interferon sensitivity determining region (ISDR) were determined in pretreatment serum samples from 47 patients with chronic hepatitis C (36 infected by HCV genotype 1b and 11 by 3a). Among HCV genotype 1b-infected patients, virus load was lower (P = .003) and the number of NS5A-ISDR amino acid changes was higher (P = .001) in long-term responders than in non-long-term responders, but there were no differences in quasispecies complexity. Multivariate analysis showed a close association between response to interferon and NS5A-ISDR phenotype. Phylogenetic analysis showed that isolates from non-long-term responders clustered apart from the majority of isolates from long-term responders. There was no association between virologic features and therapeutic response in HCV genotype 3a-infected patients. In conclusion, low virus load and mutant NS5A-ISDR phenotype are closely associated with long-term response to interferon in HCV genotype 1b- but probably not in 3a-infected patients.

Mutations in the NS5A gene of hepatitis C virus in North American patients infected with HCV genotype 1a or 1b.

Previous studies from Japan have described an association between a conserved sequence within the hepatitis C virus (HCV) genome and resistance to interferon (IFN) therapy for patients infected with HCV genotype 1b [Enomoto et al. (1995): Journal of Clinical Investigation 96: 224-230; Enomoto et al. (1996): New England Journal of Medicine 334:77-81]. The present study examines amino acid sequences surrounding the putative Interferon Sensitivity Determining Region (ISDR) of the NS5A gene of HCV in 21 North American patients with genotype 1a or 1b infection receiving recombinant IFN therapy. The ISDR consensus or intermediate pattern was observed in 13 of 14 NS5A clones from North American patients infected with genotype 1b. However, we found no evidence of the consensus ISDR sequence in any NS5A clones isolated from 15 patients with genotype 1a infection. In select cases, gel shift analysis showed no significant changes in the clonal frequency of the putative ISDR domain of HCV genotype 1a or 1b infected patients who were either nonresponsive to IFN therapy, or relapsed following withdrawal of IFN therapy. These results suggest that a conserved ISDR domain is neither associated with, nor responsible for, IFN resistance in North American patients infected with HCV genotype 1a, and demonstrate a need for further investigation into the reported association between ISDR consensus sequences and IFN resistance in genotype 1b clones.