Hepatitis C Virus Protease Inhibitors Research Articles

Direct-Acting Antiviral Therapy for Patients with Chronic Hepatitis C Infection and Decompensated Cirrhosis.

Patients with chronic hepatitis C virus (HCV) infection and decompensated cirrhosis are an important population for antiviral therapy yet under-represented in clinical trials. HCV direct-acting antiviral (DAA) therapies, unlike interferon-containing regimens, can be safely utilized in decompensated patients. Per guidelines from the American Association for the Study of Liver Diseases (AASLD), therapy of choice in HCV and decompensated cirrhosis is sofosbuvir, an HCV polymerase inhibitor, combined with a replication complex inhibitor (NS5A inhibitor) with or without ribavirin. Combination therapy with a HCV protease inhibitor and an NS5A inhibitor is effective in this population but is specifically not recommended in AASLD guidelines due to safety concerns. Important risk factors for further decompensation during DAA therapy are serum albumin < 3.5g/dL, MELD (Model for End-Stage Liver Disease) score > 14, or HCV genotype 3 infection. Although sustained virologic response (SVR) is achieved less often in patients with decompensated vs compensated cirrhosis, in clinical studies response rates are > 80%. Both Child-Turcotte-Pugh Class at baseline and viral genotype can affect these response rates. Achieving SVR lowers risk of mortality, but to a lesser extent than in individuals with compensated cirrhosis. Likewise, treating patients for HCV infection along with successful treatment for hepatocellular carcinoma improves risks of both liver-related and overall mortality. In fewer than one third of cases, treating transplant-eligible, HCV-infected patients pre-transplant enables their delisting from transplant wait lists.

Virtual Screening of Telaprevir and Danoprevir Derivatives for Hepatitis C Virus NS3/4A Protease Inhibitors

Background: The NS3/4A protease is a common target for inhibiting hepatitis C virus (HCV) infection. Telaprevir and danoprevir have promising activity in combating these virus-associated infections and are used as HCV protease inhibitors. Objective: In this study, we have found different tested derivative compounds for developing various HCV NS3/4A protease inhibitors by designing the chemical structures of telaprevir and danoprevir. Methods: In silico studies were carried out to find better drug candidatures from these derivative compounds. The docking studies were performed on HCV NS3/4A protease receptors (PDB: 3SV6 &amp; 5EQR) using Autodock vina. DFT, global reactivity, ADME (Absorption, distribution, metabolism &amp; excretion), and toxicity analysis were also performed for these designed compounds. The stability of the proteinligand complexes was quantified by MD simulation and MMPBSA studies. Results: 16 derivatives (four as telaprevir and twelve as danoprevir) have satisfied higher binding affinity of interaction with NS3/4A protease, compared to telaprevir and danoprevir. These compounds have also passed all rules of drug candidature to serve as the best HCV inhibitors. Conclusion: These 16 ligands can be effective inhibitors against HCV NS3/4A protease. These ligands must obey the drug candidate behavior by in vitro and in vivo analysis to inhibit HCV infection.

Deciphering the Molecular Mechanism of HCV Protease Inhibitor Fluorination as a General Approach to Avoid Drug Resistance

Third generation Hepatitis C virus (HCV) NS3/4A protease inhibitors (PIs), glecaprevir and voxilaprevir, are highly effective across genotypes and against many resistant variants. Unlike earlier PIs, these compounds have fluorine substitutions on the P2-P4 macrocycle and P1 moieties. Fluorination has long been used in medicinal chemistry as a strategy to improve physicochemical properties and potency. However, the molecular basis by which fluorination improves potency and resistance profile of HCV NS3/4A PIs is not well understood. To systematically analyze the contribution of fluorine substitutions to inhibitor potency and resistance profile, we used a multi-disciplinary approach involving inhibitor design and synthesis, enzyme inhibition assays, co-crystallography, and structural analysis. A panel of inhibitors in matched pairs were designed with and without P4 cap fluorination, tested against WT protease and the D168A resistant variant, and a total of 22 high-resolution co-crystal structures were determined. While fluorination did not significantly improve potency against the WT protease, PIs with fluorinated P4 caps retained much better potency against the D168A protease variant. Detailed analysis of the co-crystal structures revealed that PIs with fluorinated P4 caps can sample alternate binding conformations that enable adapting to structural changes induced by the D168A substitution. Our results elucidate molecular mechanisms of fluorine-specific inhibitor interactions that can be leveraged in avoiding drug resistance.

Hepatitis C virus drugs that inhibit SARS-CoV-2 papain-like protease synergize with remdesivir to suppress viral replication in cell culture.

Effective control of COVID-19 requires antivirals directed against SARS-CoV-2. We assessed 10 hepatitis C virus (HCV) protease-inhibitor drugs as potential SARS-CoV-2 antivirals. There is a striking structural similarity of the substrate binding clefts of SARS-CoV-2 main protease (Mpro) and HCV NS3/4A protease. Virtual docking experiments show that these HCV drugs can potentially bind into the Mpro substrate-binding cleft. We show that seven HCV drugs inhibit both SARS-CoV-2 Mpro protease activity and SARS-CoV-2 virus replication in Vero and/or human cells. However, their Mpro inhibiting activities did not correlate with their antiviral activities. This conundrum is resolved by demonstrating that four HCV protease inhibitor drugs, simeprevir, vaniprevir, paritaprevir, and grazoprevir inhibit the SARS CoV-2 papain-like protease (PLpro). HCV drugs that inhibit PLpro synergize with the viral polymerase inhibitor remdesivir to inhibit virus replication, increasing remdesivir’s antiviral activity as much as 10-fold, while those that only inhibit Mpro do not synergize with remdesivir.

A Small Molecule-Controlled Cas9 Repressible System

CRISPR-Cas9 has been developed into a powerful molecular tool for genome engineering, and it has revolutionized the field of biomedical research. Despite the tremendous potential of CRISPR-Cas9 in biomedical research, precise control of CRISPR-Cas9 over the dose and exposure time is important to expand its applications. In this study, we fused Cas9 with a peptide termed small molecule-assisted shut-off (SMASh) consisting of a protease domain and a degron domain derived from hepatitis C virus (HCV). The presence of SMASh allows tight control of the Cas9 stability via a clinically approved HCV protease inhibitor asunaprevir (ASV). We showed that the engineered Cas9 responded to ASV administration and rapidly degraded in a dose- and time-dependent manner. Cas9 degradation was reversible upon ASV removal that restored the gene editing activity. We also showed that limiting the level of Cas9 in cells increased the specificity of gene editing. The SMASh tag therefore provides an effective tool to control Cas9 stability, allowing an improvement in the accuracy, safety, and versatility of the CRISPR-Cas9 system for genome editing and gene regulation studies.

Hepatitis C reinfection with protease inhibitor-resistant hepatitis C virus in an HIV-coinfected MSM.

There is an ongoing global hepatitis C virus (HCV) epidemic mainly related to high-risk behaviour in persons who inject drugs (PWID) and in HIV-infected men who have sex with men (MSM) which continues to fuel the HCV epidemic. Treatment of HCV infection with direct antiviral therapy (DAA) has been very successful in the last decade. Main obstacles for HCV elimination are HCV reinfections observed in PWID and HIV-infected MSM. We present here an HIV-infected MSM patient who has been reinfected thrice with HCV. The virus which was investigated from his last reinfection episode reveals transmission of a newly acquired HCV protease inhibitor (PI) resistance, despite not having been exposed to HCV-PIs during his last DAA therapy.

Ring-Closing Metathesis on Commercial Scale: Synthesis of HCV Protease Inhibitor Simeprevir.

The key macrocyclization step in the synthesis of simeprevir, a hepatitis C virus (HCV) antiviral drug, was studied. N-Boc substitution on the diene precursor changes the site of insertion of the metathesis catalyst and, consequently, the kinetic model of the ring closing metathesis (RCM), enabling a further increase in the macrocyclization efficiency under simulated high dilution (SHD) conditions. NMR of the inserted species of both first and second generation RCM catalysts are reported and discussed.

AASLD/IDSA HCV Guidance: Recommendations for Testing, Managing, and Treating Hepatitis C

Clinical Liver DiseaseVolume 12, Issue 5 p. 117-117 IntroductionFree Access AASLD/IDSA HCV Guidance: Recommendations for Testing, Managing, and Treating Hepatitis C First published: 14 December 2018 https://doi.org/10.1002/cld.791Citations: 18AboutSectionsPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Abstract Watch a video presentation of this article Watch the interview with the author The landscape of treatment for hepatitis C virus (HCV) infection has evolved substantially since the introduction of highly effective HCV protease inhibitor therapies in 2011. The pace of change has increased rapidly as numerous new drugs with different mechanisms of action have become available over the past few years. To provide healthcare professionals with timely guidance as new therapies become available and are integrated into HCV regimens, the Infectious Diseases Society of America (IDSA) and American Association for the Study of Liver Diseases (AASLD), developed a web-based process for the rapid formulation and dissemination of evidence-based, expert-developed recommendations for hepatitis C management. The AASLD/IDSA guidance on hepatitis C addresses management issues ranging from testing and linkage to care, the crucial first steps toward improving health outcomes for HCV-infected persons, to the optimal treatment regimen in particular patient situations. Recommendations are evidence based and rapidly updated as new data from peer-reviewed research become available. For each treatment option, recommendations reflect the best possible management for a given patient and a given point of disease progression. Recommendations are rated with regard to the level of the evidence and strength of the recommendation. The AASLD/IDSA guidance on hepatitis C is supported by the membership-based societies and not by pharmaceutical companies or other commercial interests. The governing boards of AASLD and IDSA have appointed an oversight committee of 4 co-chairs and selected panel members from the societies. This guidance should be considered a living document in that the recommendations are updated frequently as new information and treatments become available. Please listen to Dr Ray Chung discuss the most recent AASLD/IDSA HCV guideline update.1 Reference 1 AASLD-IDSA. Recommendations for testing, managing, and treating hepatitis C. http://www.hcvguidelines.org Citing Literature Volume12, Issue5November 2018Pages 117-117 ReferencesRelatedInformation

Molecular Mechanism of Resistance in a Clinically Significant Double-Mutant Variant of HCV NS3/4A Protease

Despite significant progress in hepatitis C virus (HCV) protease inhibitor (PI) drug design, resistance remains a problem causing treatment failure. Double-substitution variants, notably Y56H/D168A, have emerged in patients who fail therapy with a PI-containing regimen. The resistance conferred by Asp168 substitutions has been well characterized and avoided in newer inhibitors. However, an additional mutation at Tyr56 confers resistance to even the most robust inhibitors. Here, we elucidate the molecular mechanisms of resistance for the Y56H/D168A variant against grazoprevir (and four analogs), paritaprevir, and danoprevir through inhibition assays, co-crystal structures, and molecular dynamics simulations. The PIs' susceptibility to Y56H/D168A varies, with those stacking on the catalytic His57 losing the most potency. For such inhibitors, the Y56H substitution disrupts favorable stacking interactions with the neighboring catalytic His57. This indirect mechanism of resistance threatens to cause multi-PI failure as all HCV PIs in clinical development rely on interactions with the catalytic triad.

Superinfection and cure of infected cells as mechanisms for hepatitis C virus adaptation and persistence

RNA viruses exist as a genetically diverse quasispecies with extraordinary ability to adapt to abrupt changes in the host environment. However, the molecular mechanisms that contribute to their rapid adaptation and persistence in vivo are not well studied. Here, we probe hepatitis C virus (HCV) persistence by analyzing clinical samples taken from subjects who were treated with a second-generation HCV protease inhibitor. Frequent longitudinal viral load determinations and large-scale single-genome sequence analyses revealed rapid antiviral resistance development, and surprisingly, dynamic turnover of dominant drug-resistant mutant populations long after treatment cessation. We fitted mathematical models to both the viral load and the viral sequencing data, and the results provided strong support for the critical roles that superinfection and cure of infected cells play in facilitating the rapid turnover and persistence of viral populations. More broadly, our results highlight the importance of considering viral dynamics and competition at the intracellular level in understanding rapid viral adaptation. Thus, we propose a theoretical framework integrating viral and molecular mechanisms to explain rapid viral evolution, resistance, and persistence despite antiviral treatment and host immune responses.

In Vitro Antiviral Activity and Resistance Profile of the Next-Generation Hepatitis C Virus NS3/4A Protease Inhibitor Glecaprevir.

ABSTRACTGlecaprevir (formerly ABT-493) is a novel hepatitis C virus (HCV) NS3/4A protease inhibitor (PI) with pangenotypic activity. It inhibited the enzymatic activity of purified NS3/4A proteases from HCV genotypes 1 to 6 in vitro (half-maximal [50%] inhibitory concentration = 3.5 to 11.3 nM) and the replication of stable HCV subgenomic replicons containing proteases from genotypes 1 to 6 (50% effective concentration [EC50] = 0.21 to 4.6 nM). Glecaprevir had a median EC50 of 0.30 nM (range, 0.05 to 3.8 nM) for HCV replicons containing proteases from 40 samples from patients infected with HCV genotypes 1 to 5. Importantly, glecaprevir was active against the protease from genotype 3, the most-difficult-to-treat HCV genotype, in both enzymatic and replicon assays demonstrating comparable activity against the other HCV genotypes. In drug-resistant colony selection studies, glecaprevir generally selected substitutions at NS3 amino acid position A156 in replicons containing proteases from genotypes 1a, 1b, 2a, 2b, 3a, and 4a and substitutions at position D/Q168 in replicons containing proteases from genotypes 3a, 5a, and 6a. Although the substitutions A156T and A156V in NS3 of genotype 1 reduced susceptibility to glecaprevir, replicons with these substitutions demonstrated a low replication efficiency in vitro. Glecaprevir is active against HCV with most of the common NS3 amino acid substitutions that are associated with reduced susceptibility to other currently approved HCV PIs, including those at positions 155 and 168. Combination of glecaprevir with HCV inhibitors with other mechanisms of action resulted in additive or synergistic antiviral activity. In summary, glecaprevir is a next-generation HCV PI with potent pangenotypic activity and a high barrier to the development of resistance.

Immune response of Th17-associated cytokines by peripheral blood mononuclear cells from patients with chronic hepatitis C virus infection

Hepatitis C virus (HCV) chronic infection causes severe cellular immune dysfunction. Here, we investigated the production of Th17-associated cytokines by peripheral blood mononuclear cells (PBMCs) of untreated patients with HCV, patients presenting an early virologic response (EVR) after 12weeks of treatment with interferon-α plus ribavirin with or without HCV protease inhibitors, and patients who were nonresponders to HCV therapy. PBMCs were stimulated with HCV core and nonstructural antigens, and the production of Th17-associated cytokines was measured with a Milliplex MAP immunoassay. Core-stimulated PBMCs from both untreated and nonresponder patients produced interleukin (IL)-17A, and vigorous production of IL-17A in response to NS3 antigen was only verified in the untreated group. Nonresponder patients also produced IL-17F after core antigen stimulation. IL-21 production was unaltered in the three groups of patients, whereas IL-17E and IL-22 were not detected. The production of Th17 cytokines by cells from patients showing an EVR was insignificant. IL-17A and IL-17F levels were not correlated with alanine aminotransferase levels or viremia. However, advanced fibrosis was associated with higher IL-17A production in T0 cells stimulated with core antigen. Untreated patients with HCV and patients who were nonresponders to antiviral treatment differed in their PBMC immune responses of Th17-associated cytokines. The early virological response to antiviral treatment dramatically decreased Th17 immune responses to HCV antigens.

Sofosbuvir, velpatasvir and voxilaprevir combination for the treatment of hepatitis C

ABSTRACTIntroduction: The advent of direct-acting antiviral (DAA) treatments for chronic hepatitis C virus (HCV) infection has dramatically increased rates of cure. However, there remain difficult-to-treat populations, including patients with genotype 3 infection and cirrhosis, and limited salvage treatment options for those that have failed first-line DAA therapy.Areas covered: This is a review of the preclinical and clinical development of sofosbuvir/velpatasvir/voxilaprevir (SOF/VEL/VOX), an interferon-free, oral, once daily, pangenotypic treatment for chronic HCV infection. All relevant literature from 2015 through June of 2017 is included.Expert commentary: Voxilaprevir, a second-generation HCV protease inhibitor, in combination with the already approved combination of sofosbuvir and velpatasvir, was evaluated in the POLARIS trials and found to be a safe and effective regimen. Patients with prior DAA treatment failure, genotype 3, cirrhosis and/or unfavorable resistance profiles all achieved cure rates of 96% or greater. The most distinctive role for this potent regimen may prove to be as a salvage regimen for patients who have failed previous DAA therapy.

NS3 genomic sequencing and phylogenetic analysis as alternative to a commercially available assay to reliably determine hepatitis C virus subtypes 1a and 1b.

ObjectiveTo evaluate the use of hepatitis C virus (HCV) NS3 sequencing as alternative to the comercially available Versant HCV 2.0 reverse hybridization line-probe assay (LiPA 2.0) to determine HCV genotype 1 (HCV-1) subtypes.Patients and methodsA cohort of 104 patients infected by HCV-1 according to LiPA 2.0 was analyzed in a cross-sectional study conducted in patients seen from January 2012 to June 2016 at an outpatient clinic in Buenos Aires, Argentina.ResultsThe samples were included within well supported subtype clades: 64 with HCV-1b and 39 with HCV-1a infection. Twenty of the HCV-1a infected patientes were included in a supported sub-clade “1” and 19 individuals were among the basal sub-clade “2”. LiPA 2.0 failed to subtype HCV-1 in 20 (19.2%) individuals. Subtype classification determined by NS3 direct sequencing showed that 2/18 (11.1%) of the HCV-1a-infected patients as determined by LiPA 2.0 were in fact infected by HCV-1b. Of the HCV-1b-infected according to LiPA 2.0, 10/66 (15.2%) patients showed HCV-1a infection according to NS3 sequencing. Overall misclassification was 14.3% (κ-index for the concordance with NS3 sequencing = 0.635). One (1%) patient was erroneously genotyped as HCV-1 and was revealed as HCV genotype 4 infection.ConclusionsGenomic sequencing of the HCV NS3 region represents an adequate alternative since it provides reliable genetic information. It even distinguishes between HCV-1a clades related to resistance-associated substitutions to HCV protease inhibitors, it provides reliable genetic information for genotyping/subgenotyping and simultaneously allows to determine the presence of resistance-associated substitutions to currently recommended DAAs.

Asunaprevir Evokes Hepatocytes Innate Immunity to Restrict the Replication of Hepatitis C and Dengue Virus.

Type I Interferon-mediated innate immunity against Flaviviridae, such as Hepatitis C virus (HCV) and Dengue virus (DENV), involves TLR3, RIG-I-like receptor (RLR) and JAK-STAT signal pathways. Asunaprevir is a newly developed HCV protease inhibitor for HCV treatment. Whether, asunaprevir activates innate immunity to restrict viral infection is unclear. Thus, this study investigates the effect of asunaprevir on innate immunity and its influence on HCV and DENV infection. Huh 7.5.1, Hep-G2 cells, JFH-1 infection model, and DENV-2 infection were used for the analysis. The activity of asunaprevir-regulated innate immunity signal pathway was assessed with IFN-β promoter or IFN-stimulated responsive element (ISRE) reporter assays and immunoblotting of key signal proteins. siRNA-mediated MAVS and TRIF knockdown of cells was performed to assess the effect of asunaprevir-regulated innate immunity against HCV and DENV. Asunaprevir treatment activated ISRE and IFN-β promoter-luciferase activities and signaling proteins in the JAK-STAT, MAVS, and TRIF pathways in Huh 7.5.1 cells. Asunaprevir-mediated signaling activation was decreased in MAVS-knockdown cells. Importantly, both RNA and protein levels of DENV-2 NS3 were decreased in asunaprevir-treated Huh 7.5.1 and HepG2 cells. In MAVS-knockdown cells, the restrictive effect of asunaprevir on HCV and DENV was attenuated. Our findings reveal an unexpected activity of asunaprevir, the activation of MAVS dependent innate immunity to restrict HCV and DENV infection.

Mechanisms involved in liver damage resolution after hepatitis C virus clearance

Abstract Worldwide, the hepatitis C virus (HCV) infection is a leading etiology of cirrhosis and hepatocellular carcinoma (HCC). The main complications of chronic HCV infection are fibrosis, cirrhosis and HCC. Nowadays, there are several options accessible for HCV treatment, such as direct-acting antiviral agents (DAAs), including HCV protease inhibitors, polymerase inhibitors, and NS5A inhibitors. Once the virus is eliminated after the specific antiviral treatments, patients should try to re-establish their metabolic functions efficiently from an environment where there was great cellular destruction. Another goal for the liver can range from fibrosis to decompensate cirrhosis. For this reason, upon the use of DAAs therapy, assuming that SVR is reached, the use of antifibrotic drugs is increasing in order to improve liver regeneration by decreasing fibrotic tissue generated by HCV. Liver fibrosis is defined as the excessive accumulation of extracellular matrix proteins because of the interaction of a number of different cell types, among them hepatic stellate cells. Once the causative agent of damage is removed, the progression of liver disease is attenuated. However, if the patient has an advanced state of fibrosis or cirrhosis, hepatic regeneration becomes a challenge where numerous known and unknown cellular mechanisms are involved. Fortunately, there are drugs that facilitate this process of reversion, however, it is still not clear that conditions favor the success of this regression.

Anti-HCV protease of diketopiperazines produced by the Red Sea sponge-associated fungus Aspergillus versicolor

Hepatitis C virus (HCV) infection is a global problem due to the difficulties in developing a protective vaccine. In this work, we demonstrated that the ethyl acetate extract of the endophytic fungus Aspergillus versicolor exhibited significant activity against HCV NS3/4A protease with IC50 value of 30 μg/mL. The fungus was isolated from the Red Sea black sponge Spongia officinalis and identified by its morphology and 18S rDNA. Large-scale fermentation of the fungus followed by chromatographic purification with silica gel, Sephadex LH-20 and semipreparative HPLC of the active extract led to isolation of some known metabolites related to cyclodipeptides and the so-called diketopiperazines (DKPs). The DKP, cyclo(L-Tyr-L-Pro), displayed strong effect as HCV protease inhibitor with IC50 value of 8.2 μg/mL. A computational docking study of cyclo(L-Tyr-L-Pro) against HCV protease was used to formulate a hypothetical mechanism for the inhibitory activity of the active compound on the tested enzyme.

Development of a rapid phenotypic test for HCV protease inhibitors with potential use in clinical decisions.

Approximately 185 million people worldwide are chronically infected with hepatitis C virus (HCV). The first-wave of approved NS3 protease inhibitors (PIs) were Telaprevir and Boceprevir, which are currently discontinued. Simeprevir is a second-wave PI incorporated into the Brazilian hepatitis C treatment protocol. Drug resistance plays a key role in patients' treatment regimen. Here, we developed a simple phenotypic assay to evaluate the impact of resistance mutations in HCV NS3 protease to PIs, using a protein expression vector containing wild type NS3 protease domain and NS4A co-factor. We analyzed the impact of five resistance mutations (T54A, V36M, V158I, V170I and T54S+V170I) against Telaprevir, Boceprevir and Simeprevir. Protein purifications were performed with low cost methodology, and enzymatic inhibition assays were measured by FRET. We obtained recombinant proteases with detectable activity, and IC50 and fold change values for the evaluated PIs were determined. The variant T54A showed the highest reduction of susceptibility for the PIs, while the other four variants exhibited lower levels of reduced susceptibility. Interestingly, V170I showed 3.2-fold change for Simeprevir, a new evidence about this variant. These results emphasize the importance of enzymatic assays in phenotypic tests to determine which therapeutic regimen should be implemented.

Resistance-associated mutations to HCV protease inhibitors naturally pre-existed in HIV/HCV coinfected, treatment-naïve patients

Presently, it has been approved to treat hepatitis C virus (HCV) infection with protease inhibitors (PIs). In the present study, we aimed to illustrate the natural prevalence of HCV NS3/4A PI resistance mutations in HIV/HCV coinfected, treatment-naïve patients. Population sequence analysis of the NS3/4A protease was conducted in 96 HIV/HCV coinfected, treatment-naïve patients. Complete HCV NS3/4A sequence information was obtained from 70 (72.92%) samples, including 68 patients (97.14%) with genotype 1b and 2 patients (2.86%) with genotype 2a. A total of 21 patients (30.88%) of the 68 patients with HCV genotype 1b showed amino acid substitutions associated with HCV PI resistance. Mutation F43S was observed in 1.47% of patients with genotype 1b. The mutations of T54S, Q80K/R, R155K, A156G and D168A/E/G were found in 4.41%, 1.47%/1.47%, 2.94%, 23.53% and 1.47%/1.47%/1.47% of patients with genotype 1b, respectively. In addition, 4.41% of patients with genotype 1b showed double mutations in the NS3 region. The multiple mutations of Q80R+R155K+D168G and Q80K+R155K+A156G+D168A were detected in 1.47% and 1.47% of patients with HCV genotype 1b, respectively. The most predominant HCV genotype was 1b in patients with HIV/HCV coinfection. Naturally occurring mutations resistant to HCV PIs (simeprevir, vaniprevir, boceprevir, telaprevir, asunaprevir and paritaprevir) pre-existed in patients with HIV/HCV genotype 1b coinfection. The effects of baseline PI resistance on treatment outcome should be further analyzed.

Computational Modelling in Studies for Hepatitis C Virus (HCV) NS3 Protease.

Hepatitis C virus (HCV) infected up to 3% of global human population. More than 350 thousand die annually due to liver cirrhosis and hepatocellular carcinoma, developed at the late stages of the disease. The typical ways of HCV transmission are: transfusion of contaminated blood and blood products; sharing syringes among intravenous drug users; use of poorly sterilized medical instruments in certain countries with bad sterilization practice. HCV is hard to identify, at early stages the disease is asymptomatic and progresses slowly. HCV RNA genome is highly variable, and thus interferes developing of a vaccine. HCV NS3 protease has received close attention as the promising drug target. Recent approval of Boceprevir and Telaprevir, the first inhibitors of HCV NS3 protease, has let increase effectiveness of anti-HCV therapy. Though these new medicines show drawbacks in drug resistance and genotype coverage, second and third generation of HCV protease inhibitors will overcome them. Computational modelling had an impact role in these discoveries. Involvement of modelling in studies for Hepatitis C (HCV) NS3 protease is considered in this review.