Impact of a baseline polymorphism on the emergence of resistance to the hepatitis C virus nonstructural protein 5A replication complex inhibitor, BMS-790052

The influence of naturally occurring polymorphisms on the potency of the HCV nonstructural protein 5A (NS5A) replication complex inhibitor, BMS-790052, was investigated by evaluating hybrid replicons in which the entire NS5A coding region of genotype (GT) la and 1b laboratory (lab) strains (H77c and Con1) were replaced with the corresponding regions of specimens collected from 10 GT-1a- and 6 GT-1b-infected subjects. For baseline (BL) specimens, with no previously observed resistance variants identified by population sequencing, the median 50% effective concentration (EC(50) ) values for BMS-790052 were similar for the clinically derived and lab strains. A Q30R variant was observed at viral breakthrough (VBT) in one of the GT-1a-infected subjects. Because the lowest plasma exposure of BMS-790052 observed in this subject was 117 nM and the median 50% effective concentration value for a GT-1a H77c replicon containing a Q30R substitution is ~7 nM, a rigorous investigation was initiated to determine the basis for resistance. Three approaches were used: (1) replacement of the entire H77c NS5A or (2) replacement of the N-terminal region of NS5A, with sequence from BL and day 14, and (3) substitution of specific amino acids. A BL polymorphism (E62D) did not contribute resistance to BMS-790052; however, the linked variant, Q30R-E62D, conferred high-level resistance in vitro and is likely responsible for VBT in vivo. CONCLUSION: Our data show that a BL polymorphism with minimal effect on the anti-HCV effect of BMS-790052 can affect the emergence of resistance and significantly affect clinical outcome. This work establishes a clear, systematic approach to monitor resistance to NS5A inhibitors in the clinic.     

Genotypic and phenotypic analysis of variants resistant to hepatitis C virus nonstructural protein 5A replication complex inhibitor BMS-790052 in humans: in vitro and in vivo correlations

The NS5A replication complex inhibitor, BMS-790052, inhibits hepatitis C virus (HCV) replication with picomolar potency in preclinical assays. This potency translated in vivo to a substantial antiviral effect in a single-ascending dose study and a 14-day multiple-ascending dose (MAD) monotherapy study. However, HCV RNA remained detectable in genotype 1a-infected patients at the end of the MAD study. In contrast, viral breakthrough was observed less often in patients infected with genotype 1b, and, in several patients, HCV RNA declined and remained below the level of quantitation (<25 IU/mL) through the duration of treatment. Here, we report on the results of the genotypic and phenotypic analyses of resistant variants in 24 genotype 1-infected patients who received BMS-790052 (1, 10, 30, 60, and 100 mg, once-daily or 30 mg twice-daily) in the 14-day MAD study. Sequence analysis was performed on viral complementary DNA isolated from serum specimens collected at baseline and days 1 (4, 8, and 12 hours), 2, 4, 7, and 14 postdosing. Analyses of the sequence variants (1) established a correlation between resistant variants emerging in vivo with BMS-790052 treatment and those observed in the in vitro replicon system (major substitutions at residues 28, 30, 31, and 93 for genotype 1a and residues 31 and 93 for genotype 1b); (2) determined the prevalence of variants at baseline and the emergence of resistance at different times during dosing; and (3) revealed the resistance profile and replicative ability (i.e., fitness) of the variants. Conclusion: Although resistance emerged during monotherapy with BMS-790052, the substantial anti-HCV effect of this compound makes it an excellent candidate for effective combination therapy.     

SUMOylation of nonstructural 5A protein regulates hepatitis C virus replication

Viruses exploit cellular SUMOylation machinery to favour their own propagation. We show that NS5A is a target protein of small ubiquitin‐like modifier (SUMO) and is SUMOylated at lysine residue 348. We demonstrated that SUMOylation increased protein stability of NS5A by inhibiting ubiquitylation, and SUMOylation was also required for protein interaction with NS5B. These data imply that SUMO modification may contribute to HCV replication. Indeed, silencing of UBC9 impaired HCV replication in Jc1‐infected cells, and HCV replication level was also significantly reduced in SUMO‐defective subgenomic replicon cells. Taken together, these data indicate that HCV replication is regulated by SUMO modification of NS5A protein. We provide evidence for the first time that HCV exploits host cellular SUMO modification system to favour its own replication.     

Dual therapy with the nonstructural protein 5A inhibitor, daclatasvir, and the nonstructural protein 3 protease inhibitor, asunaprevir, in hepatitis C virus genotype 1b-infected null responders

Patients with chronic hepatitis C virus (HCV) infection and previous null response to pegylated interferon (Peg-IFN) and ribavirin (RBV) have limited therapeutic options. HCV genotype 1 is the most common worldwide and the most difficult to treat; genotype 1b is the most common subtype of genotype 1 outside North America. The enhanced antiviral activity achieved by combining two direct-acting antiviral (DAA) agents may improve clinical outcomes. This open-label, phase IIa study included 10 patients with chronic HCV genotype 1b infection and previous null response (<2 log(10) reduction in HCV RNA after 12 weeks) to Peg-IFN and RBV. Patients received dual DAA treatment for 24 weeks with the nonstructural protein 5A replication complex inhibitor, daclatasvir (60 mg once-daily), and the nonstructural protein 3 protease inhibitor, asunaprevir (initially 600 mg twice-daily, then subsequently reduced to 200 mg twice-daily). The primary efficacy endpoint was the proportion of patients with sustained virologic response (SVR) at 12 weeks post-treatment (SVR(12) ). Nine patients completed 24 weeks of treatment; 1 patient discontinued treatment after 2 weeks. In the 9 patients who completed the full course of treatment, HCV RNA was undetectable at week 8 and remained undetectable through the end of treatment; all 9 patients achieved SVR(12) and SVR(24) . HCV RNA also remained undetectable post-treatment in the patient who discontinued after 2 weeks. There was no viral breakthrough. Diarrhea and headache, generally mild, were the most common adverse events; transaminase elevations were reported in 3 patients, but did not result in discontinuation. CONCLUSIONS: Dual therapy with daclatasvir and asunaprevir, without Peg-IFN and RBV, can achieve high SVR rates in difficult-to-treat patients with HCV genotype 1b infection and previous null response to Peg-IFN and RBV.     

Tailoring interferon dose and monitoring viral load in hepatitis C virus genotype 1b infected patients: a pilot study

BACKGROUND AND AIMS: Complete [biochemical and virological) primary response remains the first goal of any antiviral therapy and its early assessment could be particularly useful in the management of the high viral load, genotype 1b infected patients, who have the worst chance of response. We evaluated whether tailoring interferon dose according to pre-treatment viral load and early monitoring of quantitative HCV-RNA could either improve or predict the results of recombinant alpha-2a interferon treatment in these patients. PATIENTS: Fifty-three consecutive genotype 1b HCV-infected patients, stratified in two groups by viral load (cut off 6 MEq/ml), received randomly 6 or 9 MU of recombinant alpha-2a interferon thrice weekly for 6 months, followed by 6 MU for another 6 months. METHODS: HCV-RNA was measured [b-DNA] assay) two months apart prior to therapy, at baseline, after 2 weeks of therapy and monthly thereafter. RESULTS: In the high viraemic group, complete primary response was observed in 80% of patients treated with high dose recombinant alpha 2a interferon and only in 14.3% of low dose treated patients [p<0.03]. In low viraemic patients, complete primary response was 53. 8% in low dose patients and 80% (8 out of 10) in the high dose group. Sustained response was 60% in high viraemic patients treated with high dose and absent in those treated with low dose [p<0.05]. One log viral load decrease at 2 or 4 weeks showed 0.87 and 0.80 positive predictive values, 0.95 and 1.0 negative predictive values with 96% and 100% sensitivities and 83% and 70% specificities. CONCLUSIONS: 6 MU recombinant alpha-2a interferon thrice weekly schedules were completely ineffective in the large majority (85.7%) of patients with viral load above 6 million HCV-RNA copies/ml and the treatment failure could be predicted by lack of one log viral load decrease after 2-4 weeks of treatment.     

Phosphorylation of hepatitis C virus nonstructural protein 5A modulates its protein interactions and viral RNA replication

The study of the hepatitis C virus (HCV) has been hindered by the lack of in vitro model systems. The recent development of HCV subgenomic RNA replicons has permitted the study of viral RNA replication in cell culture; however, the requirements for efficient replication of replicons in this system are poorly understood. Many viral isolates do not function as replicons and most require conserved changes, termed adaptive mutations, to replicate efficiently. In this report, we focus on the HCV nonstructural protein 5A (NS5A), a frequent locus for adaptive mutation. We found the interaction between NS5A and human vesicle-associated membrane protein-associated protein A (hVAP-A), a cellular target N-ethylmaleimide-sensitive factor attachment protein receptor, to be required for efficient RNA replication: NS5A mutations that blocked interaction with hVAP-A strongly reduced HCV RNA replication. Further analyses revealed an inverse correlation between NS5A phosphorylation and hVAP-A interaction. A subset of the previously identified adaptive mutations suppressed NS5A hyperphosphorylation and promoted hVAP-A binding. Our results support a model in which NS5A hyperphosphorylation disrupts interaction with hVAP-A and negatively regulates viral RNA replication, suggesting that replicon-adaptive mutations act by preventing the phosphorylation-dependent dissociation of the RNA replication complex.     

The nonstructural 5A protein of hepatitis C virus genotype 1b does not contain an interferon sensitivity-determining region

BACKGROUND: The nonstructural (NS) 5A protein of hepatitis C virus (HCV) has been suggested to contain an interferon (IFN) sensitivity-determining region (ISDR). METHODS: We studied whether the degree of viral decline on day 1 is associated with differences in NS5A amino acid sequences among patients receiving IFN- alpha. RESULTS: Phylogenetic analyses of the full-length protein and of functional domains showed no relationship between the baseline protein sequence and the antiviral response. NS5A quasispecies sequences showed no differences in the number of mutations in the putative ISDR relative to a prototype sequence between responders and nonresponders or according to IFN- alpha antiviral efficacy. No relationship was found between antiviral efficacy at 24 h and the baseline sequence of any NS5A region. Amino acid changes were observed in a few cases at 24 h in both responders and nonresponders, but no consistent pattern of amino acid shifts was observed, ruling out the possibility that IFN- alpha selected IFN-resistant variants. CONCLUSION: Our findings show that there is no ISDR in the HCV genotype 1 NS5A protein and that the NS5A sequence does not influence the capacity of IFN- alpha to block viral replication. The findings do not rule out a role for NS5A in subsequent viral clearance.     

利巴韦林累积剂量对基因1型慢性丙型肝炎患者病毒学应答率的影响

目的 研究利巴韦林累积剂量对基因1型慢性丙型肝炎患者病毒学应答率的影响.方法 对哈尔滨医科大学附属第二医院感染病科进行聚乙二醇干扰素α-2a联合利巴韦林治疗的225例基因1型慢性丙型肝炎患者进行回顾性分析.根据利巴韦林累积剂量将患者分为<60%、60%～79%、80%～97%和>97%4组,探讨利巴韦林累积剂量与病毒学应答率的关系.数据行F检验或x2检验.结果 利巴韦林累积剂量≤97%的发生率为43.1% (97/225例),明显高于聚乙二醇干扰素α-2a的27.1%(61/225例)(x2=12.641,P=0.001).利巴韦林累积剂量<60%组的18例患者中,5例有持续性病毒学应答(SVR),SVR率为27.8%明显低于>97%组的65.6%(84/128例)、80%～97%组的60.5%(26/43例)和60%～79%组的58.3%(21/36例)(x2=9.538,P=0.023).利巴韦林累积剂量<60%组获得治疗结束时病毒学应答(ETVR)的13例患者中,8例复发,复发率明显高于>97%组的20.0%(21/105例)、80%～97%组的23.5%(8/34例)和60%～79%组的27.6%(8/29例)(x2=10.837,P=0.013).在获得快速病毒学应答(RVR)的患者中,利巴韦林累积剂量>97%组为25例、80%～97%组为9例、60%～79%组为7例、<60%组为4例,SVR分别为23(92.0%)、8、6和3例(x2=1.098,P=0.778).结论 轻度利巴韦林减量不影响基因1型慢性丙型肝炎患者的SVR,利巴韦林累积剂量<60%的患者复发率高,SVR率低.

Abstract：

Objective To study the impact of ribavirin cumulative dose on virological response rates in genotype 1 hepatitis C virus(HCV)infected patients.Methods The medical records of 225 genotype 1 chronic hepatitis C(CHC)patients treated with peginterferon α-2a plus ribavirin were retrospectively analyzed.These patients were divided into four groups according to ribavirin cumulative dose:>97%,80%-97%,60%-79%and<60%of standard cumulative dose.The relationship between ribavirin cumulative dose and virological response rates was studied.Data as analyzed by chisquare test or F test.Results The incidence of ribavirin cumulative dose<97%was 43.1%(97/225),which was higher than peginterferon alfa-2a(27.1%,61/225)(x2=12.641,P=0.001).The sustained virological response rate(SVR)was 27.8%(5/18)in group of ribavirin cumulative dose <60%,which was much lower than those in groups of ribavirin cumulative dose>97%(65.6%,84/128),80%-97%(60.5%,26/43),60%-79%(58.3%,21/36)(x2=9.538,P=0.023).The relapse rate was 61.5%(8/13)in group of ribavirin cumulative dose<60%,which was significantly higher than those in groups of ribavirin cumulative dose>97%(20.0%,21/105),80%-97%(23.5% ,8/34),60%-79%(27.6%,8/29)(x2=10.837,P-0.013).Among patients achieved rapid virological response(RVR),SVR in groups of ribavirin cumulative dose>97%,80%-97%,60%-79%and<60 % of standard dose were 92.0%(23/25),88.9%(8/9),85.7%(6/7)and 75.0%(3/4),respectively(x2=1.098,P=0.778).Conclusiom Mlid reduction of ribavirin dose not affect SVR of genotype 1 HCV infected patients.However,the relapse rate is high and SVR is low in patients treated with ribavirin cumulative dose<60% of standard dose.     

Short-term antiviral efficacy of BILN 2061, a hepatitis C virus serine protease inhibitor, in hepatitis C genotype 1 patients

BACKGROUND AND AIMS: Novel, potent, and well-tolerated hepatitis C virus (HCV) drugs are needed. BILN 2061 is a potent and specific inhibitor of HCV serine protease in vitro. Preclinical toxicology data and studies in healthy volunteers supported the administration of BILN 2061 to patients with HCV infection. METHODS: The antiviral efficacy, pharmacokinetics, and tolerability of 25, 200, and 500 mg BILN 2061 twice daily given as monotherapy for 2 days in 31 patients infected with chronic genotype 1 HCV infection and with minimal liver fibrosis (Ishak score of 0-2) were assessed in a placebo-controlled, double-blind pilot study. In 2 subsequent placebo-controlled studies of similar design, 200 mg BILN 2061 twice daily was administered for 2 days to 10 patients with advanced liver fibrosis (Ishak score of 3 or 4) and to 10 patients with compensated cirrhosis (Ishak score of 5 or 6). RESULTS: Viral RNA reductions of 2-3 log 10 copies/mL were achieved in most of the patients. There was a trend toward a higher number of patients receiving 500 mg BILN 2061 achieving a viral RNA reduction > or =3 log(10) copies/mL as compared with patients receiving 25 mg BILN 2061. Advanced fibrosis or compensated cirrhosis did not affect the antiviral efficacy of BILN 2061. BILN 2061 was well tolerated in all studies. CONCLUSIONS: BILN 2061 is a well-tolerated and very active compound that reduced serum viral RNA concentrations after 2 days of treatment in patients infected with genotype 1 HCV independent of the degree of fibrosis. Nevertheless, further clinical trials are on hold pending resolution of animal toxicity issues.     

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection.

An association has been reported between mutations in the amino acid residues 2209-2248 of the nonstructural protein 5A (NS5A) gene (interferon-sensitivity determining region [ISDR]) and interferon efficacy in hepatitis C virus (HCV)-1b infection. This relationship was analyzed in chronic HCV-2 infection. Forty patients with HCV-2a and 35 with HCV-2b were treated with interferon alfa for 6 months with a total dose of 468 to 860 million units. Pretreatment NS5A sequences were determined by direct sequencing. A higher complete and sustained response rate was observed in HCV-2a than in HCV-2b (70% vs. 34%; P =.003). Serum HCV-RNA levels were lower in complete responders than nonresponders in HCV-2a (P =.049) and HCV-2b (P =. 02). The number of amino acid mutations was greater in complete responders than nonresponders in NS5A2193-2228 (the region corresponding to the ISDR of HCV-1b) alone (P =.049), or NS5A2163-2228 consisting of NS5A2193-2228 plus its upstream region (P =.02) in HCV-2a, but not in HCV-2b. A significant inverse correlation was observed between serum HCV-RNA levels and the number of amino acid mutations in NS5A2193-2228 (P =.003) or NS5A2163-2228 (P =.005) in HCV-2a. With multivariate analysis, the number of substitutions in NS5A was an independent predictor for complete response in HCV-2a (odds ratio: 6.4; P =.03). Interferon efficacy is associated with amino acid variations in the NS5A protein in HCV-2a infection.     

HCV非结构蛋白5A对HIV长末端重复序列影响的初步探讨

目的本研究拟探讨HCV非结构蛋白5A(NS5A)对HIV长末端重复序列(long terminal repeat,LTR)影响,从而为HCV对HIV的影响提供实验依据。方法将构建的LTR启动子驱动的荧光素酶(Luc)报告基因表达质粒(pGL3-LTR-Luc)和含HCV NS5A基因的表达质粒pCNS5A共转染肝癌细胞株(Huh7细胞),采用免疫细胞化学技术、Western Blot及逆转录聚合酶链反应检测HCV NS5A蛋白及mRNA的表达;本实验分三组,将质粒pGL3-LTR-Luc(空白组)、质粒pRc/CMV+pGL3-LTR-Luc(对照组)、质粒pCNS5A+pGL3-LTR-Luc(实验组)分别转染Huh7细胞,48 h后收集细胞,采用Luc活性检测LTR的活性,以观察HCV NS5A对LTR的调控影响。所得荧光活性值以均数±标准差表示,采用Levene's方差齐性检验,多组间比较采用单因素方差分析,两两比较行LSD-t检验。结果转染pcNS5A质粒的Huh7细胞质经RT-PCR及Western Blot检测,HCV NS5A mRNA及蛋白在细胞中获得表达。方差分析结果提示LTR荧光活性在三组间有明显的差异(F=7.876,P=0.002),进一步比较各组间的差异,结果提示共转染质粒pcNS5A+pGL3-LTR-Luc组的Huh7细胞中Luc相对活性(22 476±4471)明显高于单转染pGL3-LTR-Luc组(15 887±3039,P=0.002)及共转染质粒pRc/CMV+pGL3-LTR-Luc组(16 321±4162,P=0.008),差异有统计学意义。结论表达HCV NS5A的质粒pCNS5A成功转染至Huh7细胞;HCV NS5A蛋白能激活HIV LTR,提示HCV NS5A可能为HCV促进HIV复制的分子机制之一。     

贵州地区慢性乙型肝炎病毒感染者病毒基因亚型研究

目的调查贵州省B、C基因型慢性HBV感染者的病毒基因亚型。方法PCR扩增HBV P区长309 bp的基因片段,扩增产物分别经限制性内切酶NciⅠ、VspⅠ、BstEⅡ酶切,琼脂糖凝胶电泳,根据酶切图谱多态性,用限制性片段长度多态性分析（PCR-RFLP）检测HBV C基因亚型。直接测序确定B基因亚型、对178例用S基因限制性片段长度多态性鉴定为B、C基因型的不同临床类型慢性HBV感染者进行亚型分析。结果84例C基因型HBV感染者中,27例（32.14%）为C1亚型、56例（66.67%）为C2亚型,1例为C1、C2亚型混合感染。94例B基因型HBV感染者中,93例（98.94%）为Ba、1例为Bj亚型感染。从无症状乙型肝炎表面抗原携带者、CHB到肝硬化/肝癌,C1亚型在各组中的比例逐渐降低,分别为60.00%、30.65%和16.67%;而C2亚型在各对应组中的分布逐渐增高,分别为40.00%、67.74%和83.33%。结论贵州地区B、C基因型慢性HBV感染者中,以Ba、C2亚型为主。C1、C2亚型在疾病中的分布有一定差异。PCR-RFLP分析HBV C1、C2亚型,方法简便、特异性强,适合较大样本分析,可用于流行病学调查。     

Characterization of the effects of hepatitis C virus nonstructural 5A protein expression in human cell lines and on interferon-sensitive virus replication

The hepatitis C virus (HCV) nonstructural 5A (NS5A) protein has been implicated in the inherent resistance of HCV to interferon (IFN) antiviral therapy in clinical studies. Biochemical studies have demonstrated that NS5A interacts in vitro with and inhibits the IFN-induced, RNA-dependent protein kinase, PKR, and that NS5A interacts with at least one other cellular kinase. The present study describes the establishment and characterization of various stable NS5A-expressing human cell lines, and the development of a cell culture-based assay for determining the inherent IFN resistance of clinical NS5A isolates. Human epithelioid (Hela) and osteosarcoma (U2-OS) cell lines were generated that express NS5A under tight regulation by the tetracycline-dependent promoter. Maximal expression of NS5A occurred at 48 hours following the removal of tetracycline from the culture medium. The half-life of NS5A in these cell lines was between 4 to 6 hours. NS5A protein expression was localized cytoplasmically, with a staining pattern consistent with the location of the Golgi apparatus and endoplasmic reticulum. In the majority of cell lines, no obvious phenotypic changes were observed. However, three genotype 1b NS5A-expressing osteosarcoma cell lines exhibited cytopathic effect and severely reduced proliferation as a result of high-level NS5A expression. Full-length NS5A protein isolated from a genotype 1b IFN-nonresponsive patient (NS5A-1b) was capable of rescuing encephalomyocardititis virus replication during IFN challenge up to 40-fold, whereas a full-length NS5A-1a and an interferon sensitivity determining region (ISDR) deletion mutant (NS5A-1a-triangle upISDR) isolated from a genotype 1a IFN-nonresponsive patient showed no rescue activity. The NS5A-1b and NS5A-1a proteins also rescued vesicular stomatitis virus replication during IFN treatment by two- to threefold. These data cummulatively suggest that NS5A expression alone can render cells partially resistant to the effects of IFN against IFN-sensitive viruses, and that in some systems, these effects may be independent of the putative ISDR. A scenario is discussed in which the NS5A protein may employ multiple strategies contributing to IFN resistance during HCV infection.     

Dramatic response of hepatitis C patients chronically infected with hepatitis C virus genotype 3 to sofosbuvirbased therapies in Punjab,Pakistan: A prospective study

AIM To prospectively evaluate the efficacy of sofobuvir(SOF) in hepatitis C patients infected with hepatitis C virus(HCV) genotype 3 in Pakistan.METHODS The present study was performed with the coordination of gastroenterology and pathology departments of Shalamar Hospital Lahore from August 2014 to May 2016. The total number of patients included in this study was 1375 and all of them were infected with HCV genotype 3. On the basis of drug combinations, all the patients were separated into two groups. The first group of patients was treated for 24 wk with SOF(Sovaldi? by Gilead Sciences) plus ribavirin(RBV) [Ribazol? by Getz Pharma Pakistan(PVT) Ltd], while the patients of the second group were treated with SOF + RBV + pegylatedinterferon(peg IFN) alfa-2 a(Ropegra by Roach) for 12 wk. HCV genotyping and viral load measurement were performed on fully automated Abbott Real-Time PCR system(Abbott m24 sp automated nucleic acid extraction system and Abbott m2000 rt amplification system; abbott Molecular, Des Plaines, IL, United States). For the assessment of sustained virological response(SVR), all HCV RNA negative patients were followed for 12weeks after the treatment completion. Any patient with less than 12 IU/m L viral load after 12 wk of treatment completion was considered as a sustained virological responder(SVR-12).RESULTS A total of 1375 patients chronically infected with HCV genotype 3 were treated with two drug combinations SOF + RBV and SOF + RBV + peg IFN alfa-2 a. On the basis of these drug combinations, patients were divided into two groups(first and second). Overall SVR-12 was excellent in both groups(99.17% and 97.91%). Older patients( 40 years) of second group showed lower SVR-12(93.46%) compared to first group older patients(98.79%), while in the younger patients of both groups, the SVR-12 rate was almost the same(99.54% in first group and 99.05% in second group). No such difference regarding SVR-12 rate was seen in males and females of first group patients(99.68% and 98.88%, respectively), while in second group the males were found to be better responders compared to females(98.96% and 95%). The SVR-12 rate in previously treated patients of first group was better(99.34%) than second group(93.70%), while na?ve patients of second group were marginally better responders(99.25%) than first group(97.80%). Rapid viral response at week-4 was found to be a very effective predictor for assessing the SVR rate at this stage of therapy in both groups. Headache, anemia and fatigue were common side effects in both groups either treated with SOF + RBV or SOF + RBV + peg IFN alfa-2 a, while the overall percentage of the side effects was higher in second group.CONCLUSION The remarkable SVR response rate of HCV genotype 3 infected patients to SOF provided a new way to look forward to eliminate hepatitis C from our region.     

Effect of mutation in the hepatitis C virus nonstructural 5B region on HCV replication

Background We have reported that the presence of a mutation at the hepatitis C virus (HCV) nonstructural protein 5B (NS5B), defined as a change in amino acids at sites specific for a different reported genotype, was related to complete response (CR) to interferon (IFN) therapy in patients with chronic hepatitis C (CHC) with genotype 1b. The present study assessed the impact of the NS5B mutation on the replication of HCV in these patients.Methods Genotype-specific mutations of HCV NS5B were determined by direct sequencing. We measured HCV-RNA titers in serum by real-time detected polymerase chain reaction (PCR), and serum HCV core protein levels (as a marker of HCV-RNA replication) were measured using an enzyme immunoassay in patients with CHC genotype 1b. RNA-dependent RNA polymerase (RdRp) activity was measured by Behrens method in liver cirrhosis patients infected with HCV (n = 13) and in those infected with hepatitis B virus (HBV; n = 2).Results The titers of HCV-RNA (n = 44) and the levels of HCV core protein (n = 41) were significantly lower in patients with the HCV genotype 1b mutant compared with wild-type HCV (P < 0.05). RdRp activity in liver tissue did not show any correlation with the HCV NS5B mutation.Conclusions HCV NS5B genotype-specific mutations in HCV genotype 1b may influence HCV replication.     

Efficacy of short-term interferon therapy for patients infected with hepatitis C virus genotype 2a

BACKGROUND AND AIMS: The efficacy of interferon (IFN)-based antiviral therapy for chronic hepatitis C (CHC) varies depending on predictive factors such as hepatitis C virus (HCV) genotype and viral load. For patients with good predictive factors, a low dose and short course of IFN-based therapy may be adequate. However, there is no evidence about the optimal duration of IFN-based therapy for these patients. The aim of this study was to clarify whether the duration of IFN therapy could be shortened to less than the conventional treatment period for patients with good predictive factors. METHODS: A total of 25 treatment-naive CHC patients with genotype 2a were randomized to receive either IFN monotherapy for 24 wks (group A: long-term IFN therapy, n = 13) or for 6 wks (group B: short-term IFN therapy, n = 12). Patients were monitored for HCV RNA and routine liver function tests during and following treatment, and data were examined according to intention-to-treat analysis. RESULTS: Eleven of 13 patients in group A and all patients in group B completed IFN therapy according to the original planned schedule. At the end of the treatment, viral clearance occurred in all patients. However, 4 patients in group A and 5 in group B relapsed within 6 months of follow-up. There was no significant difference of sustained response rate between group A (53.8%) and group B (58.3%). Among patients who had HCV viral load of <100 kIU/ml, the sustained response rate was 83.3% (5/6) in group A and 100% (5/5) in group B. CONCLUSIONS: In this study, our results suggest that the duration of IFN therapy can be shortened to less than 24 wks in patients with good predictive factors. Further studies, however, should examine the optimal regimen of IFN therapy based on the backgrounds of patients.