Hepatitis C Virus Nonstructural Protein 5A Research Articles

Ser235 phosphorylation of hepatitis C virus NS5A is required for NS5A dimerization and drug resistance

Hepatitis C virus (HCV) infection is recognized as a major causative agent of chronic hepatitis, cirrhosis, and hepatocellular carcinoma. HCV non-structural protein 5A (NS5A) is a dimeric phosphoprotein with a hyperphosphorylated form to act as a switch that regulates HCV replication and assembly. NS5A inhibitors have been utilized as the scaffold for combination therapy of direct-acting antiviral agents (DAA). However, the mode of action of NS5A inhibitors is still unclear due to the lack of mechanistic detail regarding NS5A phosphorylation and dimerization in the HCV life cycle. It has been demonstrated that phosphorylation of NS5A at Ser235 is essential for RNA replication of the JFH1 strain. In this report, we found that NS5A phosphomimetic Ser235 substitution (Ser-to-Asp mutation) formed a dimer that was resistant to disruption by NS5A inhibitors as was the NS5A resistance-associated substitution Y93H. Phosphorylation of NS5A at Ser235 residue was required for the interaction of two NS5A-WT molecules in JFH1-based cell culture system but not absolutely required for dimerization of the NS5A-Y93H mutant. Interestingly, HCV nonstructural proteins from the subgenomic replicon NS3-5A was required for NS5A-WT dimerization but not required for NS5A-Y93H dimerization. Our data suggest that spontaneous Ser235 phosphorylation of NS5A and ensuing dimerization account for resistance of the JFH1/NS5A-Y93H mutant to NS5A inhibitors.

ASPP2 binds to hepatitis C virus NS5A protein via an SH3 domain/PxxP motif-mediated interaction and potentiates infection.

Hepatitis C virus (HCV) infects millions of people worldwide and is a leading cause of liver disease. Despite recent advances in antiviral therapies, viral resistance can limit drug efficacy and understanding the mechanisms that confer viral escape is important. We employ an unbiased interactome analysis to discover host binding partners of the HCV non-structural protein 5A (NS5A), a key player in viral replication and assembly. We identify ASPP2, apoptosis-stimulating protein of p53, as a new host co-factor that binds NS5A via its SH3 domain. Importantly, silencing ASPP2 reduces viral replication and spread. Our study uncovers a previously unknown role for ASPP2 to potentiate HCV RNA replication.

Design and Synthesis of Novel Bis-Imidazolyl Phenyl Butadiyne Derivatives as HCV NS5A Inhibitors.

In today’s global plan to completely eradicate hepatitis C virus (HCV), the essential list of medications used for HCV treatment are direct-acting antivirals (DAAs), as interferon-sparing regimens have become the standard-of-care (SOC) treatment. HCV nonstructural protein 5A (NS5A) inhibitors are a very common component of these regimens. Food and Drug Administration (FDA)-approved NS5A inhibitors, although very potent, do not have the same potency against all eight genotypes of HCV. Therefore, this study aims to synthesize NS5A inhibitor analogues with high potency pan-genotypic activity and high metabolic stability. Starting from an NS5A inhibitor scaffold previously identified by our research group, we made several modifications. Two series of compounds were created to test the effect of changing the length and spatial conformation (para-para vs. meta-meta-positioned bis-imidazole-proline-carbamate), replacing amide groups in the linker with imidazole groups, as well as different end-cap compositions and sizes. The frontrunner inhibits genotype 1b (Con1) replicon, with an EC50 value in the picomolar range, and showed high genotypic coverage with nanomolar range EC50 values against four more genotypes. This together with its high metabolic stability (t½ > 120 min) makes it a potential preclinical candidate.

Development of a Synthesis Process for a Novel HCV NS5A Inhibitor, Emitasvir

A new approach to the synthesis of Emitasvir (DAG181), a small molecule hepatitis C virus (HCV) nonstructural protein 5A (NS5A) inhibitor, is described. Enantioselective enzymatic desymmetrization ...

Genotype 3-hepatitis C virus' last line of defense.

Chronic infection with hepatitis C virus (HCV) is one of the leading causes of liver disease globally, affecting approximately 71 million people. The majority of them are infected with genotype (GT) 1 but infections with GT3 are second in frequency. For many years, GT3 was considered to be less pathogenic compared to other GTs in the HCV family due to its favorable response to interferon (IFN)-based regimen. However, the growing evidence of a higher rate of steatosis, more rapid progression of liver fibrosis, and lower efficacy of antiviral treatment compared to infection with other HCV GTs has changed this conviction. This review presents the specifics of the course of GT3 infection and the development of therapeutic options for GT3-infected patients in the era of direct-acting antivirals (DAA). The way from a standard of care therapy with pegylated IFN-alpha (pegIFNα) and ribavirin (RBV) through a triple combination of pegIFNα + RBV and DAA to the highly potent IFN-free pangenotypic DAA regimens is discussed along with some treatment options which appeared to be dead ends. Although the implementation of highly effective pangenotypic regimens is the most recent stage of revolution in the treatment of GT3 infection, there is still room for improvement, especially in patients with liver cirrhosis and those who fail to respond to DAA therapies, particularly those containing inhibitors of HCV nonstructural protein 5A.

Phytochemical analysis of Berberis lyceum methanolic extract and its antiviral activity through the restoration of MAPK signaling pathway modulated by HCV NS5A

Objective: To evaluate the antiviral activity and phytochemicals of selected plant extracts and their effect on the mitogen-activated protein kinase (MAPK) signaling pathway modulated by hepatitis C virus (HCV) nonstructural protein 5A (NS5A). Methods: A total of ten plant extracts were initially screened for their toxicities against HepG2 cells. The non-toxic plants were tested for their inhibitory effect on the expression of HCV NS5A at both mRNA and protein levels using real-time PCR and Western blotting assays, respectively. The differential expression of the genes associated with MAPK pathway in the presence of NS5A gene and plant extract was measured through real-time PCR. Subsequently, the identification of secondary metabolites was carried out by phytochemical and HPLC analysis. Results: The phytochemical profiling of Berberis lyceum revealed the presence of alkaloids, phenols, saponins, tannins, flavonoids, carbohydrates, terpenoids, steroids, and glycosides. Similarly, quercetin, myricetin, gallic acid, caffeic acid, and ferulic acid were identified through HPLC analysis. The methanolic extract of Berberis lyceum strongly inhibited HCV RNA replication with an IC50 of 11.44 µg/mL. RT-PCR and Western blotting assays showed that the extract reduced the expression of HCV NS5A in a dose- dependent manner. Berberis lyceum extract also attenuated NS5A- induced dysregulation of the MAPK signaling pathway. Conclusions: Our findings suggest that Berberis lyceum extract strongly inhibits HCV propagation by reducing HCV NS5A- induced perturbation of MAPK signaling.

Real‐world efficacy of sofosbuvir plus velpatasvir therapy for patients with hepatitis C virus‐related decompensated cirrhosis

Combination therapy with sofosbuvir (SOF) plus velpatasvir (VEL) is approved for patients with hepatitis C virus (HCV)-related decompensated cirrhosis. We analyzed the real-world efficacy of SOF/VEL therapy. Thirty-three patients with HCV-related decompensated cirrhosis (25 and eight patients with Child B and C, respectively) were treated with SOF/VEL for 12weeks. The HCV non-structural protein (NS)5A and NS5B drug resistance-associated substitutions (RASs) were determined by direct sequencing. Thirty-two of 33 patients completed the treatment, but the remaining patient discontinued the therapy during third week of the treatment due to aggravation of hepatic encephalopathy. Serum HCV-RNA became negative during the treatment in all patients but relapsed after the end of therapy in five patients. In total, 28 out of 33 patients (85%) achieved sustained virological response 12weeks following completion of treatment (SVR12). The SVR12 rate was 96% in patients with Child B, but significantly lower, at 50%, in patients with Child C (P < 0.05). In genotype 1b HCV-infected patients, all eight patients without baseline NS5A RASs, but only three of seven patients with RASs, achieved SVR12. Multivariate analysis identified Child B (odds ratio, 35.8 for Child C; P = 0.045) as an independent predictor of SVR12. Median serum albumin levels significantly increased only in patients who achieved SVR12. Child-Pugh scores improved in 16 of 28 patients (57%) following achievement of SVR12. The effect of SOF/VEL therapy is lower for patients with Child C. Improvement of hepatic function is expected after viral eradication with SOF/VEL therapy in patients with decompensated cirrhosis.

Viral Interference Between Dengue Virus and Hepatitis C Virus Infections.

Both dengue virus (DENV) and hepatitis C virus (HCV) belong to the Flaviviridae family and could induce hepatitis. We aimed to investigate the interference between them. In total, 515 patients confirmed with dengue fever (DF) were enrolled. Thirty-two patients (6.21%) were seropositive for anti-HCV; 12 of 32 anti-HCV-positive patients had detectable HCV-RNA at presentation of DF. The proportion of dengue hemorrhagic fever was comparable between patients with or without anti-HCV and between those with or without HCV-RNA. Eleven of 32 patients received HCV-RNA testing during a median interval of 23 months after DF, which revealed significantly increased HCV-RNA levels (5.43 ± 0.77 vs 3.09 ± 1.24 log IU/mL, follow-up vs acute-DF phase; P = .003). Four of 11 patients with baseline HCV-RNA values before DF demonstrated a nadir viremia during acute DF. We also included age-, sex-, and follow-up duration–matched HCV-monoinfected patients as controls; higher delta HCV-RNA changes were demonstrated in patients with DF than in controls during the follow-up period (2.34 ± 1.15 vs –0.27 ± 0.76 log IU/mL; P < .001). Further in vitro experiments showed that HCV nonstructural protein 5A was downregulated in Con1 HCV replicon cells infected by DENV1. These clinical and experimental findings suggested possible viral interference in DENV/HCV. However, HCV viremia did not affect the disease outcomes of DF.

Hepatitis C virus nonstructural protein 5A perturbs lipid metabolism by modulating AMPK/SREBP-1c signaling

BackgroundSteatosis is an important clinical manifestation associated with chronic hepatitis C virus (HCV) infection. AMP-activated protein kinase (AMPK), a major mediator of lipid metabolism, regulates HCV-associated hepatic steatosis, but the underlying mechanisms remain obscure. Here we investigated the mechanism of HCV nonstructural protein 5A (NS5A)-induced lipid accumulation by the AMPK/SREBP-1c pathway.MethodsWe generated model mice by injecting recombinant lentiviral particles expressing the NS5A protein (genotype 3a) via the tail vein. The serum levels of alanine aminotransferase (ALT), free fatty acids (FFAs) and triglycerides (TG) were examined. H&E and Oil Red O staining were used to examine lipid droplets. Immunohistochemistry staining, quantitative real-time PCR and Western blotting were used to determine the expression of lipogenic genes.ResultsOur results showed that the serum levels of ALT, FFAs and TG, as well as the accumulation of hepatic lipid droplets, were increased significantly in mice infected with NS5A-expressing lentiviral particles. NS5A inhibited AMPK phosphorylation and increased the expression levels of sterol regulatory element binding protein-1c (SREBP-1c), acetyl-coenzyme A carboxylase 1 (ACC1) and fatty acid synthase (FASN) in vivo and in vitro. Further investigation revealed that pharmacological activation or ectopic expression of AMPK neutralized the upregulation of SREBP-1c, ACC1 and FASN, and ameliorated hepatic lipid accumulation induced by NS5A. Ectopic expression of SREBP-1c enhanced NS5A-induced hepatic lipid accumulation, which was dramatically reversed by pharmacological activation of AMPK.ConclusionsCollectively, we demonstrate that NS5A induces hepatic lipid accumulation via the AMPK/SREBP-1c pathway.

RACK1 mediates rewiring of intracellular networks induced by hepatitis C virus infection.

Hepatitis C virus (HCV) is a positive-strand RNA virus replicating in a membranous replication organelle composed primarily of double-membrane vesicles (DMVs) having morphological resemblance to autophagosomes. To define the mechanism of DMV formation and the possible link to autophagy, we conducted a yeast two-hybrid screening revealing 32 cellular proteins potentially interacting with HCV proteins. Among these was the Receptor for Activated Protein C Kinase 1 (RACK1), a scaffolding protein involved in many cellular processes, including autophagy. Depletion of RACK1 strongly inhibits HCV RNA replication without affecting HCV internal ribosome entry site (IRES) activity. RACK1 is required for the rewiring of subcellular membranous structures and for the induction of autophagy. RACK1 binds to HCV nonstructural protein 5A (NS5A), which induces DMV formation. NS5A interacts with ATG14L in a RACK1 dependent manner, and with the ATG14L-Beclin1-Vps34-Vps15 complex that is required for autophagosome formation. Both RACK1 and ATG14L are required for HCV DMV formation and viral RNA replication. These results indicate that NS5A participates in the formation of the HCV replication organelle through interactions with RACK1 and ATG14L.

SPSB2 inhibits hepatitis C virus replication by targeting NS5A for ubiquitination and degradation.

Hepatitis C virus (HCV) replication involves many viral and host factors. Host factor SPRY domain- and SOCS box-containing protein 2(SPSB2) belongs to SPSB family, and it recruits target proteins by the SPRY domain and forms E3 ubiquitin ligase complexes by the SOCS box. As an adaptor protein, it can regulate the host’s response to infection, but little is known about whether SPSB2 plays a role in HCV replication. In the present study, we found that HCV infection significantly upregulated the mRNA and protein levels of SPSB2 in HCVcc-infected cells. Exogenous expression of SPSB2 in hepatoma cells decreased HCV RNA and protein levels which depended on the SOCS box, while knockdown of endogenous SPSB2 increased HCV RNA and protein levels. Additionally, we demonstrated that SPSB2 interacted with HCV structural protein E1 and nonstructural protein protein 5A (NS5A) via the C-terminal portion of the SPSB2 SPRY domain. Furthermore, SPSB2 induced NS5A ubiquitination and mediated NS5A degradation. Collectively, this study discovered host factor SPSB2 significantly inhibits HCV replication by interacting and degrading NS5A.

QSAR Studies on Thiazole Derivatives as HCV NS5A Inhibitors via CoMFA and CoMSIA Methods

Background: Hepatitis C Virus (HCV) infection is the major cause of hepatitis after transfusion. And HCV Nonstructural Protein 5A (NS5A) inhibitors have become a new hotspot in the study of HCV inhibitors due to their strong antiviral activity, rapid speed of viral removing and broad antiviral spectrum. Methods: Forty-five NS5A inhibitors were chosen to process three-dimensional quantitative structure- activity relationship (3D-QSAR) by using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) models. A training set consisting of 30 compounds was applied to establish the models and a test set consisting of 15 compounds was applied to do the external validation. Results: The CoMFA model predicted a q2 value of 0.607 and an r2 value of 0.934. And the CoMSIA model predicted a q2 value of 0.516 and an r2 value of 0.960 established on the effects of steric, electrostatic, hydrophobic and hydrogen-bond acceptor. 0.713 and 0.939 were the predictive correlation co-efficients (r2pred) of CoMFA and CoMSIA models, respectively. Conclusion: These conclusions provide a theoretical basis for drug design and screening of HCV NS5A complex inhibitors.

Safety and efficacy of elbasvir/grazoprevir for the treatment of chronic hepatitis C: current evidence.

Treatments for hepatitis C virus (HCV) have advanced greatly, becoming more efficacious with fewer adverse events, due to the availability of direct-acting antiviral agents, which target specific steps in the HCV life cycle. Recently, a combination regimen consisting of the HCV nonstructural protein 5A inhibitor elbasvir (EBR) and the HCV NS3/4A protease inhibitor grazoprevir (GZR) was approved for the treatment of patients with chronic HCV and genotypes (Gts) 1 and 4 in various countries. In Phase III trials, the combination of EBR/GZR (fixed-dose combination table or single agent) for 12 or 16 weeks of treatment with or without ribavirin resulted in a high sustained virological response at 12 weeks in treatment-naïve and treatment-experienced patients with HCV Gt 1a, 1b, 4, or 6, including special populations, such as individuals with advanced chronic kidney disease, HCV-HIV coinfection, and compensated cirrhosis. In this review, we focus on the mode of action, pharmacokinetics, clinical applications, efficacy, and safety profile of EBR/GZR, including special populations who have been considered refractory from the extensive evidence of clinical trials.

Hepatitis C Virus NS5A Protein Promotes the Lysosomal Degradation of Hepatocyte Nuclear Factor 1α via Chaperone-Mediated Autophagy.

Hepatitis C virus (HCV) infection is closely associated with type 2 diabetes. We reported that HCV infection induces the lysosomal degradation of hepatocyte nuclear factor 1 alpha (HNF-1α) via interaction with HCV nonstructural protein 5A (NS5A) protein, thereby suppressing GLUT2 gene expression. The molecular mechanisms of selective degradation of HNF-1α caused by NS5A are largely unknown. Chaperone-mediated autophagy (CMA) is a selective lysosomal degradation pathway. Here, we investigated whether CMA is involved in the selective degradation of HNF-1α in HCV-infected cells and observed that the pentapeptide spanning from amino acid (aa) 130 to aa 134 of HNF-1α matches the rule for the CMA-targeting motif, also known as KFERQ motif. A cytosolic chaperone protein, heat shock cognate protein of 70 kDa (HSC70), and a lysosomal membrane protein, lysosome-associated membrane protein type 2A (LAMP-2A), are key components of CMA. Immunoprecipitation analysis revealed that HNF-1α was coimmunoprecipitated with HSC70, whereas the Q130A mutation (mutation of Q to A at position 130) of HNF-1α disrupted the interaction with HSC70, indicating that the CMA-targeting motif of HNF-1α is important for the association with HSC70. Immunoprecipitation analysis revealed that increasing amounts of NS5A enhanced the association of HNF-1α with HSC70. To determine whether LAMP-2A plays a role in the degradation of HNF-1α protein, we knocked down LAMP-2A mRNA by RNA interference; this knockdown by small interfering RNA (siRNA) recovered the level of HNF-1α protein in HCV J6/JFH1-infected cells. This result suggests that LAMP-2A is required for the degradation of HNF-1α. Immunofluorescence study revealed colocalization of NS5A and HNF-1α in the lysosome. Based on our findings, we propose that HCV NS5A interacts with HSC70 and recruits HSC70 to HNF-1α, thereby promoting the lysosomal degradation of HNF-1α via CMA.IMPORTANCE Many viruses use a protein degradation system, such as the ubiquitin-proteasome pathway or the autophagy pathway, for facilitating viral propagation and viral pathogenesis. We investigated the mechanistic details of the selective lysosomal degradation of hepatocyte nuclear factor 1 alpha (HNF-1α) induced by hepatitis C virus (HCV) NS5A protein. Using site-directed mutagenesis, we demonstrated that HNF-1α contains a pentapeptide chaperone-mediated autophagy (CMA)-targeting motif within the POU-specific domain of HNF-1α. The CMA-targeting motif is important for the association with HSC70. LAMP-2A is required for degradation of HNF-1α caused by NS5A. We propose that HCV NS5A interacts with HSC70, a key component of the CMA machinery, and recruits HSC70 to HNF-1α to target HNF-1α for CMA-mediated lysosomal degradation, thereby facilitating HCV pathogenesis. We discovered a role of HCV NS5A in CMA-dependent degradation of HNF-1α. Our results may lead to a better understanding of the role of CMA in the pathogenesis of HCV.

Real-world virological efficacy and safety of elbasvir and grazoprevir in patients with chronic hepatitis C virus genotype 1 infection in Japan

The real-world virological efficacy and safety of an interferon (IFN)-free direct-acting antiviral (DAA) therapy with elbasvir (EBR) and grazoprevir (GZR) were evaluated in Japanese patients chronically infected with hepatitis C virus (HCV) genotype 1. The rate of sustained virologic response (SVR) and safety were analyzed in patients who started the EBR/GZR regimen between November 2016 and July 2017. SVR rates were compared based on patient baseline characteristics. Overall, 371 of 381 patients (97.4%) achieved SVR. Multivariate analysis identified a history of failure to IFN-free DAA therapy and the presence of double resistance-associated substitutions (RASs) in HCV non-structural protein 5A (NS5A) as factors significantly associated with failure to EBR/GZR treatment. The SVR rates of patients with a history of IFN-free DAA therapy and those with double RASs were 55.6 and 63.6%, respectively. In all other subpopulations, the SVR rates were more than 90%. There were no severe adverse events associated with the treatment. The EBR/GZR regimen yielded high virological efficacy with acceptable safety. Patients with a history of failure to IFN-free DAA therapy or with double RASs in HCV-NS5A remained difficult to treat with this regimen.

Successful combination of direct antiviral agents in liver-transplanted patients with recurrent hepatitis C virus.

AIMTo analyze the safety and efficiency of direct-acting antiviral (DAA) regimens in liver-transplanted patients with hepatitis C virus (HCV) reinfection.METHODSBetween January 2014 and December 2016, 39 patients with HCV reinfection after liver transplantation were treated at our tertiary referral center with sofosbuvir (SOF)-based regimens, including various combinations with interferon (IFN), daclatasvir (DAC), simeprivir (SIM) and/or ledipasvir (LDV). Thirteen patients were treated with SOF + IFN ± RBV. Ten patients were treated with SOF + DAC ± RBV. Fiveteen patients were treated with fixed-dose combination of SOF + LDV ± RBV. One patient was treated with SOF + SIM + RBV. Three patients with relapse were retreated with SOF + LDV + RBV. The treatment duration was 12-24 wk in all cases. The decision about the HCV treatment was made by specialists at our transplant center, according to current available or recommended medications.RESULTSThe majority of patients were IFN-experienced (29/39, 74.4%) and had a history of hepatocellular carcinoma (26/39, 66.7%) before liver transplantation. Sustained virological response at 12 wk (SVR12) was achieved in 10/13 (76.9%) of patients treated with SOF + IFN ± RBV. All patients with relapse were treated with fixed-dose combination of SOF + LDV + RBV. Patients treated with SOF + DAC + RBV or SOF + LDV + RBV achieved 100% SVR12. SVR rates after combination treatment with inhibitors of the HCV nonstructural protein (NS)5A and NS5B for 24 wk were significantly higher, as compared to all other therapy regimens (P = 0.007). Liver function was stable or even improved in the majority of patients during treatment. All antiviral therapies were safe and well-tolerated, without need of discontinuation of treatment or dose adjustment of immunosuppression. No serious adverse events or any harm to the liver graft became overt. No patient experienced acute cellular rejection during the study period.CONCLUSIONOur cohort of liver-transplanted patients achieved high rates of SVR12 after a 24-wk course of treatment, especially with combination of NS5A and NS5B inhibitors.

Successful retreatment with grazoprevir and elbasvir for patients infected with hepatitis C virus genotype 1b, who discontinued prior treatment with NS5A inhibitor-including regimens due to adverse events.

BackgroundSustained virologic response (SVR) by interferon and interferon-free treatment can results in the reduction of advanced liver fibrosis and the occurrence of hepatocellular carcinoma in patients infected with hepatitis C virus (HCV). Recent interferon-free treatment for HCV shortens the duration of treatment and leads to higher SVR rates, without any serious adverse events. However, it is important to retreat patients who have had treatment-failure with HCV non-structural protein 5A (NS5A) inhibitor-including regimens. Combination of sofosbuvir and ledipasvir only leads to approximately 100% SVR rates in HCV genotype (GT1b), NS5A inhibitor-naïve patients in Japan. This combination is not an indication for severe renal disease or heart disease, and these patients should be treated or retreated with a different regimen.Case summaryRetreatment with HCV non-structural protein 3/4A inhibitor, grazoprevir, and HCV NS5A inhibitor, elbasvir, successfully eradicated HCV RNA in three patients with HCV genotype 1b infection who discontinued prior interferon-free treatments including HCV NS5A inhibitors due to adverse events within 2 weeks.ConclusionRetreatment with the 12-week combination regimen of grazoprevir and elbasvir is effective for HCV GT1b patients who discontinue the HCV NS5A inhibitor-including regimens within 2 weeks. The treatment response may be related to the short duration of initial treatment, which did not produce treatment-emergent RASs.

High efficacy of sofosbuvir/velpatasvir and impact of baseline resistance‐associated substitutions in hepatitis C genotype 3 infection

Twelve weeks of the pangenotypic direct-acting antiviral (DAA) combination sofosbuvir/velpatasvir (SOF/VEL) was highly efficient in patients with hepatitis C virus (HCV) genotype 3 (GT3) infection in the ASTRAL-3 approval study. However, presence of resistance-associated substitutions (RASs) in the HCV nonstructural protein 5A (NS5A) was associated with lower treatment response. To assess the efficacy and safety of SOF/VEL±ribavirin (RBV) and the impact of NS5A RASs and RBV use on treatment outcome in HCV GT3 infection in a real-world setting. In this multicentre cohort study, GT3 patients from ten treatment centres across Germany were included. Sustained virological response was assessed 12weeks after end-of-treatment (SVR12) in modified intention-to-treat (mITT) and per-protocol analysis (PP). NS5A RASs were tested by population-based sequencing. A total of 293 GT3 patients were included. The median age was 48years, 70% were male, 25.3% were cirrhotic, 9.2% were HCV/HIV co-infected and 21.8% were treatment-experienced, including 4.1% with DAA experience. Baseline NS5A RASs (Y93H, A30K, L31M) were detected in 11.2%. RBV was added in 5% of noncirrhotic and 58.9% of cirrhotic patients, respectively. SVR12 rates for SOF/VEL±RBV were 95.9% (mITT) and 99.5% (PP), respectively. Only 1 virological relapse occurred in a cirrhotic patient previously treated with SOF/RBV. No treatment-related major adverse events occurred. Twelve weeks of SOL/VEL±RBV was safe and highly efficient in HCV GT3 across a diverse patient population. Baseline NS5A RASs were rarely observed and presence did not seem to impact SVR, regardless of the use of RBV.

Safety and Efficacy of Elbasvir/Grazoprevir in Patients With Hepatitis C Virus Infection and Compensated Cirrhosis: An Integrated Analysis

Persons with hepatitis C virus (HCV) infection are at risk of progressive liver disease, cirrhosis, and decompensation. We analyzed the effects of the direct-acting antiviral agents elbasvir and grazoprevir in patients with HCV infection and compensated cirrhosis, combining data from 6 clinical trials. We performed an integrated analysis of 402 patients with HCV genotype 1, 4, or 6 infection and Child-Pugh A compensated cirrhosis enrolled in 6 clinical trials. All patients received elbasvir/grazoprevir 50 mg/100 mg once daily, with or without ribavirin, for 12-18 weeks. The primary end point was sustained virologic response 12 weeks after completion of therapy (SVR12), defined as a level of HCV RNA <15 IU/mL. Among treatment-naïve and treatment-experienced patients receiving elbasvir/grazoprevir for 12 weeks, 97.8% (135 of 138) and 88.9% (48 of 54) achieved SVR12, respectively. Among patients receiving elbasvir/grazoprevirfor 12 weeks, addition of ribavirin did not increase the proportion of treatment-naïve patients (90.3%, 28 of 31) or treatment-experienced patients who achieved an SVR12 (91.4%, 74 of 81). All (49 of 49) treatment-experienced patients receiving elbasvir/grazoprevir with ribavirin for 16 or 18 weeks, and 93.9% (46 of 49) of patients receiving elbasvir/grazoprevir without ribavirin for 16 or 18 weeks achieved SVR12. Virologic failure was higher among patients with HCV genotype 1a infectionscompared with patients with genotype 1b or 4 infections, particularly in patients who had not responded to previous interferon therapy. Baseline tests for resistance-associated substitutions (RASs) led to an individualized approach for selecting treatment duration and established a need for ribavirin for patients with HCV genotype 1a infection and RASs, regardless of treatment history. Among patients with HCV genotype 1a infection with and without baseline RASs in HCV nonstructural protein 5A who received elbasvir/grazoprevir for 12 weeks, 73% (8 of 11) and 98% (96 of 98) achieved SVR12, respectively. Both patients with HCV genotype 1a infection with baseline RASs who received 16 or 18 weeks of elbasvir/grazoprevirand ribavirin achieved SVR12. Grade 3 or 4 increases in levels of alanine aminotransferase and aspartate aminotransferase, which did not cause symptoms, were reported in 2.3% (6 of 264) of patients receiving elbasvir/grazoprevir. Serious adverse events were reported in 3% (8 of 264) patients and no patient had a decompensation-related event. In an analysis of data from 6 clinical trials, rates of SVR12 rangedfrom 89% to 100% in patients with HCV genotype 1, 4, or 6 infections and compensated cirrhosis treated with elbasvir/grazoprevir, with or without ribavirin. Addition of ribavirin to a 12-week regimen of elbasvir/grazoprevir had little effect on the proportion of treatment-naïve or treatment-experienced patients who achieved an SVR12. However, virologic failure didnot occur in any treatment-experienced patients when theduration of elbasvir/grazoprevir and ribavirin therapy wasextended to 16 or 18 weeks. Baseline analysis of RASs (orin theabsence of this test, a history of nonresponse to interferon) canbe used to determine treatment duration andthe need for ribavirin in patients with HCV genotype1ainfection. Clinicaltrials.gov ID: NCT02092350, NCT02105662, NCT02105467, NCT02105701, NCT01717326, and NCT02105454.

Hepatitis C Virus Nonstructural 5A Protein Interacts with Abelson Interactor 1 and Modulates Epidermal Growth Factor-mediated MEK/ERK Signaling Pathway

The propagation of hepatitis C virus (HCV) is highly dependent on host cellular factors. To identify the cellular factors involved in HCV propagation, we have previously performed protein microarray assays using the HCV nonstructural 5A (NS5A) protein as a probe. Of ∼9,000 host proteins immobilized in a microarray, ∼90 cellular proteins were identified as HCV NS5A interacting partners. Of these candidates, we selected Abelson interactor 1 (Abi1) for further characterization. Binding of HCV NS5A to Abi1 was verified by both in vitro pulldown and coimmunoprecipitation assays. HCV NS5A interacted with Abi1 through regions I + II of Abi1 and domain I of NS5A. We further demonstrated that Abi1 colocalized with the HCV NS5A protein in the cytoplasm. We showed that NS5A inhibited epidermal growth factor-mediated ERK and Egr1 activations and this inhibitory activity of NS5A was nullified in Abi1-knockdown cells. Moreover, silencing of Abi1 expression impaired HCV replication, whereas overexpression of Abi1 promoted HCV propagation. Collectively, these data indicate that HCV exploits host Abi1 protein via NS5A to modulate MEK/ERK signaling pathway for its own propagation.