"Real world" efficacy of bulevirtide in HBV/HDV-related cirrhosis including people living with HIV: Results from the compassionate use programme at INMI Spallanzani in Rome, Italy.

OBJECTIVES: We describe the preliminary results of bulevirtide compassionate use in patients with hepatitis B and delta virus (HBV/HDV)-related cirrhosis and clinically significant portal hypertension, including those living with HIV. METHODS: We conducted a prospective observational study of consecutive patients. Clinical evaluation, liver function tests, bile acid levels, HDV-RNA, HBV-DNA, hepatitis B surface antigen, and liver and spleen stiffness were assessed at baseline and after treatment months 1, 2, 3, 4, 6, 9, and 12. HIV-RNA and CD4+/CD8+ count were assessed in people living with HIV. The first drug injection was administered under nurse supervision, and counselling was provided and adherence reviewed at each visit. RESULTS: In total, 13 patients (61.5% migrants) were enrolled. The median treatment duration was 11 months. At month 6, mean alanine aminotransferase (ALT) levels fell by 64.5% and mean liver and spleen stiffness decreased by 8.6 and 0.9 kPa, respectively. The mean baseline HDV-RNA was 3.34 log IU/mL and 5.10 log IU/mL in people without and with HIV (n = 5) (p = 0.28), respectively. A similar mean decline was observed in both groups: -2.06 log IU/mL and -1.93 log IU/mL, respectively (p = 0.87). A combined response (undetectable HDV RNA or ≥ -2 log IU/mL decline vs. baseline, with ALT normalization) was achieved in 66% of subjects without and in 60% of patients with HIV. Patients with HIV showed persistently undetectable HIV-RNA and a progressive increase in CD4+/CD8+ cells during treatment. No patient discontinued bulevirtide because of adverse effects. CONCLUSIONS: Preliminary results suggest that bulevirtide is feasible and well-tolerated in populations with difficult-to-treat conditions, such as those with HIV/HBV/HDV co-infection and migrants, when special attention is given to patient education. HDV-RNA decline during treatment was similar in people living with and without HIV.

Daclatasvir, sofosbuvir with or without ribavirin for 24 weeks in hepatitis C genotype 3 cirrhosis: A real-life study.

INTRODUCTION AND AIM: Cirrhotic patients with hepatitis C virus genotype 3 infection show unsatisfactory outcomes after 12 weeks' treatment with direct antiviral agents. The National Italian Drug Agency allows 24 weeks of therapy in difficult-to-treat patients, including genotype 3 cirrhotics. Aim of this study was to evaluate efficacy and safety of a 24-week course of sofosbuvir plus daclatasvir±ribavirin in this population. MATERIALS AND METHODS: 106 consecutive cirrhotics (70.8% males, mean age 55.3±7.6 years) in 8 tertiary hepatology centers received sofosbuvir plus daclatasvir for 24 weeks. Ribavirin was administered in 85 (80.2%) based expected tolerability, at a mean dose of 964±202mg/day. Baseline Child-Pugh class was A 91.5%, B 6.6%, C 1.9%; mean baseline MELD was 8.5±2.7. RESULTS: All patients completed 12-week follow-up post-treatment, and 104 (98.1%) obtained sustained virological response (100% in ribavirin -treated patients vs. 90.4% without ribavirin; p=0.04). No worsening in renal and liver function was observed, no serious adverse events occurred. Two virological failures showed resistance associated variants (Y93H and S282T). CONCLUSION: An extended 24-week treatment with sofosbuvir plus daclatasvir+ribavirin obtained 100% efficacy in genotype 3 hepatitis C cirrhosis, with very limited side effects. The role of ribavirin seems crucial in this setting and should be administered if clinically feasible.

Early improvement of glycaemic control after virus clearance in patients with chronic hepatitis C and severe liver fibrosis: a cohort study.

HCV has been recognized as the cause of chronic hepatitis C (CHC) since 1990. CHC is associated with progressive liver damage and extrahepatic conditions. Direct antiviral agents (DAAs), approved in 2014, have shown effectiveness in eradicating HCV in most patients. However, little is known about the effect of viral eradication on hepatic and extra-hepatic damage. We performed a historical cohort study of patients with HCV-related liver diseases who achieved SVR from March 2015 to October 2016 at INMI Lazzaro Spallanzani liver Unit in Rome (Italy). Repeated measures of glycaemia were analysed through a multilevel analysis framework to assess short time kinetics of blood glucose level at different times after therapy and for different levels of HCV viremia. The analysis included 205 patients. A model assessing temporal kinetics and variation of glycaemia according to HCV viremia provided evidence that blood glucose levels significantly dropped in patients with diabetes achieving SVR. Most of the variations occurred at 3-5 weeks of therapy (-17.96 mg/dL; p<0.001) and in coincidence with HCV clearance (-13.92 mg/dL; p<0.001). A weak, non-statistically significant reduction was observed in normoglycemic patients. Our study provides evidence that DAAs therapy may significantly improve glycaemic control in patients with CHC achieving SVR even when liver diseases are already established.

Lack of reduction in serum alpha-fetoprotein during treatment with direct antiviral agents predicts hepatocellular carcinoma development in a large cohort of patients with hepatitis C virus-related cirrhosis.

Risk of hepatocellular carcinoma (HCC) in hepatitis C virus cirrhotic patients treated with direct-acting antiviral agents (DAA) is still debating. We investigated it in a large cohort. The cohort comprised 1045 cirrhotic patients who completed treatment with DAA, with a median follow-up of 17.3 months after end of treatment (EOT), including 943 patients without history of HCC and 102 previously treated for HCC. The majority were men (59.9%), with compensated cirrhosis (88.8%), genotype 1b (44.7%). Univariate, multivariate analysis and Kaplan-Meier curves were performed to detect predictors of HCC in patients with and without reduction in alpha-fetoprotein (AFP) during treatment. SVR12 was 95.6%. HCC developed in 95 (9.9%), including 54 of 943 (5.7%) occurrent and 41 of 102 (39%) recurrent tumours. De novo were more often unifocal (P = 0.01) and curable (P = 0.03). AFP decreased from 16.1 ± 36.2 mg/dL (baseline) to 11.4 ± 55 mg/dL (EOT). At univariate analysis, predictors were a previous HCC, older age, higher model for end-stage liver disease, prolonged INR, lower platelets, baseline and EOT AFP, virological failure and no reduction in AFP during treatment. Kaplan-Meier curves showed lower incidence of HCC in patients showing any reduction in AFP (P = 0.001). Those with AFP <6 ng/mL had the lowest risk (P = 0.0002). At logistic regression, platelets (P = 0.009, OR 0.99 CI: 0.99-1.00), previous HCC (P < 0.000 01, OR: 10.76, 95% CI: 5.89-19.34) and no reduction in AFP during treatment (P = 0.0005, OR: 2.98, CI: 1.60-5.54) were independent predictors of HCC. In conclusion, risk of HCC after DAA treatment remains substantial. It is higher among patients with previous HCC, low platelets and without reduction in AFP during treatment.

Significance of detectable HCV RNA below the limit of quantification in patients treated with DAAs using standard and ultrasensitive protocols.

Predictive factors of HCV relapse after treatment with DAAs are poorly understood. In this study, we aimed to assess whether the residual viral load positivity observed during or at the end of treatment (EOT) has an impact on viral outcome. Blood samples were collected from 337 patients with genotypes (GT) 1a, 1b, 2, 3, and 4 HCV chronic infection, treated with DAAs to determine HCV RNA load by the Abbott RealTime HCV (ART) assay at treatment week (W) 4, at EOT, and 4, 12, 24 weeks after discontinuation. EOT and other samples with "detected <12/mL" (DNQ) were retested by an ultrasensitive protocol (USP) to confirm the result. Frequency of DNQ was analyzed in subgroups of patients and clinical conditions to assess potential correlations. At W4, 22% and 30.9% of the samples were undetectable and DNQ by ART assay, respectively, but no correlation for achieving SVR was found. In contrast, an HCV RNA cut-off of ≥50/mL at W4 was a significant predictor of therapy failure (P = 0.036, univariate analysis). At EOT, DNQ was associated to 12W treatment duration (P < 0.001) and GT1a infection (P = 0.036). Overall, 20/41 (48.8%) of DNQ samples at EOT or post-treatment W4, were confirmed by USP but only in a single case the patient experienced viral relapse. HCV RNA at W4 can predict SVR, irrespective to genotype or DAA regimen. HCV RNA DNQ at EOT is associated to shorter treatment duration and to GT1a, but is not a predictor of therapy failure.

Dendritic cells activation is associated with sustained virological response to telaprevir treatment of HCV-infected patients.

First anti-HCV treatments, that include protease inhibitors in conjunction with IFN-α and Ribavirin, increase the sustained virological response (SVR) up to 80% in patients infected with HCV genotype 1. The effects of triple therapies on dendritic cell (DC) compartment have not been investigated. In this study we evaluated the effect of telaprevir-based triple therapy on DC phenotype and function, and their possible association with treatment outcome. HCV+ patients eligible for telaprevir-based therapy were enrolled, and circulating DC frequency, phenotype, and function were evaluated by flow-cytometry. The antiviral activity of plasmacytoid DC was also tested. In SVR patients, myeloid DC frequency transiently decreased, and returned to baseline level when telaprevir was stopped. Moreover, an up-regulation of CD80 and CD86 on mDC was observed in SVR patients as well as an improvement of IFN-α production by plasmacytoid DC, able to inhibit in vitro HCV replication.

Clinical and virological predictors of sustained response with an interferon-based simeprevir regimen for patients with chronic genotype 1 hepatitis C virus infection.

Simeprevir plus peg-interferon/ribavirin (PR) is approved to treat chronic hepatitis C (HCV) genotype 1 (GT1) and GT4 infection. This study aimed to assess baseline and on-treatment the factors predictive of sustained virologic response 12-weeks post-treatment (SVR12) in patients receiving 12 weeks of simeprevir plus PR followed by 12 or 36 weeks of PR. Data from participants in four studies (QUEST-1, QUEST-2, ATTAIN and PROMISE) were pooled to examine the efficacy and safety of simeprevir+PR in HCV GT1 patients. The predictive power of baseline variables for SVR12 was assessed using univariate and multivariate logistic regression models while the relationship between early (Week 4) on-treatment response and SVR12 was analyzed by GT1 subtype and treatment experience. Data for 1160 patients were analyzed (overall SVR12: 71%). Baseline factors predictive of SVR12 were: IL28B CC genotype, GT1a/Q80K-negative, treatment-naïve/prior relapser, no cirrhosis, HCV-RNA ≤2,000,000IU/mL, albumin >42g/L, platelets >200x109 /L. Patients with HCV GT1b (86%), IL28B CC genotype (87%), and treatment-naïve patients (83%) were predicted to achieve the highest SVR12 rates and rates of rapid virologic response. Week 4 early on-treatment response identified treatment-naïve and prior relapse patients likely to achieve SVR12. Patients likely to respond to simeprevir+PR can be identified using baseline factors. Early on-treatment response predicts treatment success.

Acute hepatitis associated with clopidogrel: a case report and review of the literature.

Drug-induced hepatotoxicity is a common cause of acute hepatitis, and the recognition of the responsible drug may be difficult. We describe a case of clopidogrel-related acute hepatitis. The diagnosis is strongly suggested by an accurate medical history and liver biopsy. Reports about cases of hepatotoxicity due to clopidogrel are increasing in the last few years, after the increased use of this drug. In conclusion, we believe that physicians should carefully consider the risk of drug-induced hepatic injury when clopidogrel is prescribed.

Rapid and preemptive evaluation of individual anti-hepatitis C virus treatment outcome capability by a short-term autologous liver tissue culture system.

Hepatitis C virus (HCV) standard of care (SOC) therapy is not effective in a large percentage of patients and its efficacy may be evaluated only after several weeks. The aim of this work was to set up an in vitro liver culture assay able to preemptively predict SOC outcome by using residual liver samples from HCV patients. The in vitro response to SOC was found associated with the in vivo treatment outcome with a concordance of 100%. A wider clinical trial on a larger patient group is necessary to fully evaluate the impact of this procedure on the clinical management of untreated HCV patients.

Phylogenetic and Phylodynamic Analysis of Delta Strains Circulating in Italy.

The hepatitis delta virus (HDV) exhibits high genetic and evolutionary variability and is classified into eight genotypes (HDV-1 to -8). HDV-1 is the most widespread genotype worldwide and includes several subtypes. It predominates mainly in Europe, the Middle East, North America, and Northern Africa, and is associated with both severe and mild forms of liver disease. In this study, we performed phylogenetic and phylodynamic analyses of HDV strains circulating in Regione Lazio, Italy, to understand when these strains were introduced into the Lazio region and to define their genetic variability in Italy. Fifty HDV RNA positive patient samples were amplified using a nested RT-PCR approach targeting the HDV R0 region and sequenced. A phylogenetic tree of patient-derived sequences and reference sequences representing HDV-1 to -8 was constructed using the GTRGAMMA model in RAxML v8. The results indicated that HDV-1 was the predominant genotype with HDV-1d being the most frequently inferred subtype. HDV-1 sequences clustering with subtypes 1b and 1e were also identified. A phylodynamic analysis of HDV-1 sequences employing a Bayesian birth-death model inferred a clock rate of 3.04 × 10-4 substitutions per site per million years, with a 95% Highest Posterior Density (HPD) interval of 3.45 × 10-5 to 5.72 × 10-4. A Bayesian birth-death analysis with tree calibration based on a sample dating approach indicated multiple original sources of infection (from the late 1950s to late 1980s). Overall, these results suggest that HDV sequences from the native Italian and non-Italian patients analyzed in this study represent multiple lineages introduced across a wide period. A common ancestral origin should be excluded.

Humoral Immune Response after COVID-19 mRNA Vaccination in Patients with Liver Cirrhosis: A Prospective Real-Life Single Center Study.

Coronavirus-disease-2019 (COVID-19) mRNA vaccination effectively reduces mortality and morbidity in cirrhotic patients, but the immunogenicity and safety of vaccination have been partially characterized. The study aimed to evaluate humoral response, predictive factors, and safety of mRNA-COVID-19 vaccination in cirrhotic patients compared to healthy subjects. A prospective, single-center, observational study enrolled consecutive cirrhotic patients who underwent mRNA-COVID-19 vaccination from April to May 2021. Anti-spike-protein (anti-S) and nucleocapsid-protein (anti-N) antibodies were evaluated before the first (T0) and the second (T1) doses and 15 days after completing the vaccination. An age and sex-matched healthy reference group was included. The incidence of adverse events (AEs) was assessed. In total, 162 cirrhotic patients were enrolled, 13 were excluded due to previous SARS-CoV-2 infection; therefore, 149 patients and 149 Health Care Workers (HCWs) were included in the analysis. The seroconversion rate was similar in cirrhotic patients and HCWs at T1 (92.5% vs. 95.3%, p = 0.44) and T2 (100% in both groups). At T2, anti-S-titres were significantly higher in cirrhotic patients compared to HCWs (2776.6 vs. 1756 BAU/mL, p < 0.001]. Male sex (ß = -0.32 [-0.64, -0.04], p = 0.027) and past-HCV-infection (ß = -0.31 [-0.59, -0.04], p = 0.029) were independent predictors of lower anti-S-titres on multiple-gamma-regression-analysis. No severe AEs occurred. The COVID-19-mRNA vaccination induces a high immunization rate and anti-S-titres in cirrhotic patients. Male sex and past-HCV infection are associated with lower anti-S-titres. The COVID-19-mRNA vaccination is safe.

High prevalence of asymptomatic SARS-CoV-2 infection in a cohort of liver transplant recipients in central Italy.

Asymptomatic subjects account for 25 to 45% of SARS-CoV-2 infections, and in particular, subjects on mild immunosuppressive therapy may have symptoms masked and could spread virus for an extended period of time. To determine the cumulative incidence of symptomatic and asymptomatic SARS-CoV-2 infections and associated risk factors, we conducted a prospective clinical and serological survey in a cohort of 278 liver transplant recipients (LTRs) from Central Italy. Three different serology tests were performed every 4 months in 259 LTRs between April 2020 and April 2021: one based on raw extract of whole SARS-CoV-2 virus and two on specific viral antigens (nucleoprotein and receptor binding domain) to detect specific IgG, IgM and IgA. Hundred fifteen LTRs who reported symptoms or close contact with a SARS-CoV-2-positive subject, or had a positive serological result underwent molecular testing by standard screening procedures (RT-PCR on naso-pharyngeal swab). Thirty-one past or active SARS-CoV-2 infections were identified: 14 had positive molecular test (64% symptomatic), and 17 had positive serology only (18% symptomatic). SARS-CoV-2 infection was not statistically related to gender, age, obesity, diabetes, renal impairment, type of anti-rejection therapy or time from transplant. Asymptomatic SARS-CoV-2 cases (61.3%) were more frequent in males and in those with glomerular filtrate rate >50 ml/min. Overall, the addition of repeated serology to standard diagnostic molecular protocols increased detection of SARS-CoV-2 infection from 5.1% to 10.9%. Anti-SARS-CoV-2 seroprevalence among our LTRs (11.2%) is comparable to the general population of Central Italy, considered a medium-impact area. Only one asymptomatic subject (6%) was found to carry SARS-CoV-2 in respiratory tract at the time of serological diagnosis.

Phylogenetic and Phylodynamic Analyses of HCV Strains Circulating among Patients Using Injectable Drugs in Central Italy.

Approximately 71 million people worldwide are infected with the hepatitis C virus (HCV). Injectable drug use represents the most common route of transmission in Europe and other developed countries. We studied the molecular characteristics of the HCV infection among mono-infected people who used drugs (PWUD) in Italy. Among 208 PWUD with anti-HCV antibodies, 101 (48.6%) were HCV RNA-positive, the majority (47%) were infected with the HCV genotype (Gt)1a, followed by Gt3a (34.9%), Gt4 (9.1%), Gt1b (4.5%), and Gt2 (4.5%). Bayesian phylogenetic analyses of clustered HCV NS5B sequences from 66 HCV-positive PWUDs with available plasma samples indicated age and neighborhood proximity as the most common characteristics between closely related HCV strains. Population dynamics, as measured by a coalescent Bayesian skyline analysis, revealed an increase in HCV Gt1a infections from the mid-1980s to mid-1990s. While HCV Gt3a infections were first detected in the 1980s, patient numbers with this genotype subtype remained relatively constant. For both Gt1a and Gt3a, Birth-Death Bayesian Skyline analyses produced higher reproduction numbers post 2014. For earlier time intervals, slow growths were observed for both Gt1a and Gt3a with reproduction numbers (Re) of approximately 1. The evolutionary rates for Gt1a and Gt3a were estimated as 2.23 × 10-4 and 3.85 × 10-4, respectively.

Late Relapse and Reinfection in HCV Patients Treated with Direct-Acting Antiviral (DAA) Drugs.

The risk of hepatitis C virus (HCV) recurrence after direct-acting antiviral (DAA) treatment is <0.5%. However, the distinction between HCV RNA late relapse and reinfection still represents a challenge in virological diagnostics. The aim of this study was to employ next-generation sequencing (NGS) to investigate HCV RNA recurrence in patients achieving a sustained virologic response (SVR) at least six months post-treatment. NGS was performed on plasma samples from six HCV-positive patients (Pt1-6) treated with DAA. NGS of HCV NS5B was analyzed before treatment (T0), after HCV RNA rebound (T1), and, for Pt3, after a second rebound (T2). Reinfection was confirmed for Pt5, and for the first rebound observed in Pt3. Conversely, viral relapse was observed when comparing T0 and T1 for Pt6 and T1 and T2 for Pt3. Z-scores were calculated and used to predict whether HCV-positive patient samples at different time points belonged to the same quasispecies population. A low Z-score of <2.58 confirmed that viral quasispecies detected at T0 and T1 were closely related for both Pt1 and Pt2, while the Z-score for Pt4 was suggestive of possible reinfection. NGS data analyses indicate that the Z-score may be a useful parameter for distinguishing late relapse from reinfection.

High Levels of TRIM5α Are Associated with Xenophagy in HIV-1-Infected Long-Term Nonprogressors.

Autophagy is a lysosomal-dependent degradative mechanism essential in maintaining cellular homeostasis, but it is also considered an ancient form of innate eukaryotic fighting against invading microorganisms. Mounting evidence has shown that HIV-1 is a critical target of autophagy that plays a role in HIV-1 replication and disease progression. In a special subset of HIV-1-infected patients that spontaneously and durably maintain extremely low viral replication, namely, long-term nonprogressors (LTNP), the resistance to HIV-1-induced pathogenesis is accompanied, in vivo, by a significant increase in the autophagic activity in peripheral blood mononuclear cells. Recently, a new player in the battle of autophagy against HIV-1 has been identified, namely, tripartite motif protein 5α (TRIM5α). In vitro data demonstrated that TRIM5α directly recognizes HIV-1 and targets it for autophagic destruction, thus protecting cells against HIV-1 infection. In this paper, we analyzed the involvement of this factor in the control of HIV-1 infection through autophagy, in vivo, in LTNP. The results obtained showed significantly higher levels of TRIM5α expression in cells from LTNP with respect to HIV-1-infected normal progressor patients. Interestingly, the colocalization of TRIM5α and HIV-1 proteins in autophagic vacuoles in LTNP cells suggested the participation of TRIM5α in the autophagy containment of HIV-1 in LTNP. Altogether, our results point to a protective role of TRIM5α in the successful control of the chronic viral infection in HIV-1-controllers through the autophagy mechanism. In our opinion, these findings could be relevant in fighting against HIV-1 disease, because autophagy inducers might be employed in combination with antiretroviral drugs.

Anti-HEV IgG Avidity Testing: Utility for Diagnosing Acute and Resolved Genotype 3 Infections.

European Association of the Study of the Liver (EASL) guidelines specify HEV RNA, as well as anti-HEV IgG and IgM as positive markers for acute HEV infection. HEV RNA assay sensitivity limitations may lead to false negative test results in patients with low levels of viremia. Moreover, anti-HEV IgM positivity is not a reliable indicator for distinguishing between acute and resolved infections given the ability of this antibody to persist several months after a resolved infection. Our study aims were to assess HEV IgG avidity for diagnosing acute and resolved infections, regardless of the anti-HEV IgM serostatus, and examine assay reliability when evaluating different genotype 3 (GT3) HEV subtypes. Patient serum samples (n = 104) were tested for HEV IgG avidity by utilizing the DIA.PRO kit on a DSX automated instrument. Among patients identified with acute HEV infections, 32 were infected with GT3: GT3c (n = 5), GT3e (n = 8), 3f (n = 17) and GT3-unsubtyped (n = 2). Avidity sensitivity was 91.2% and specificity was 100%. For patients with long-lasting anti-HEV IgM persistence, an Avidity Index >70% was observed. Thus, the DIA.PRO avidity assay may be utilized to distinguish between recently acquired and resolved HEV GT3 infections. However, for equivocal results (Avidity Index > 40-70%), HEV RNA molecular testing will be required to confirm a recent infection.

Publisher Correction: Liver sinusoidal endothelial cells (LSECs) modifications in patients with chronic hepatitis C.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Liver sinusoidal endothelial cells (LSECs) modifications in patients with chronic hepatitis C.

The sinusoidal endothelial cells present in the liver (LSECs) are tipically characterized by the presence of pores (fenestrae). During some pathological conditions LSECs undergo "capillarization", a process characterized by loss of fenestrations and acquisition of a vascular phenotype. In chronic liver disease capillarization has been reported to precede the development of fibrosis. LSECs modification in the setting of HCV infection is currently poorly investigated. Considering that HCV accounts for important changes in hepatocytes and in view of the intimate connection between hepatocytes and LSECs, here we set out to study in great detail the LSECs modifications in individuals with HCV-dependent chronic hepatitis. Electron microscopy analysis, and evaluation of CD32, CD31 and caveolin-1 expression showed that in HCV infection LSECs display major morphological changes but maintain their phenotypical identity. Capillarization was observed only in cases at initial stages of fibrosis. Our findings showed that the severity of LSECs modifications appears to be correlated with hepatocytes damage and fibrosis stage providing novel insight in the pathogenesis of HCV-chronic hepatitis.

Clinical and virological properties of hepatitis C virus genotype 4 infection in patients treated with different direct-acting antiviral agents.

BACKGROUND: The efficacy of direct-acting antivirals (DAAs) depends on the hepatitis C virus (HCV) genotype 4 (GT4) subtype which are used in the treatment of HCV. We aimed to retrospectively investigate the baseline prevalence of HCV NS5A and NS5B polymorphisms and their impact on virological outcome in GT4-infected patients treated with various DAA regimens. PATIENTS AND METHODS: Available plasma samples from HCV GT4-infected patients treated with different DAA regimens were analyzed at baseline and after treatment failure, where applicable. Sanger sequencing of patient-derived NS5A and NS5B regions was performed on all available samples, while ultradeep pyrosequencing (UDPS) of NS5A and NS5B regions was performed only on samples from treatment failures at different time points. RESULTS: Sustained virological response (SVR) was achieved by 96% (48/50) of patients. Of 16 patients with baseline NS5A sequence, polymorphisms at amino acid positions associated with drug resistance were detected only at position 58: P58 (69.2%) and T58 (30.8%). Of 21 patients with baseline NS5B sequence, N142S was detected only in the two treatment failures, both with GT4d were treated with sofosbuvir (SOF)-based regimens, suggesting a potential involvement in SOF efficacy. Two patients (patient 1 [Pt1] and patient 2 [Pt2]) relapsed. In Pt1, NS5A-T56I and NS5A-Y93H/S emerged. In Pt2, NS5A-L28F emerged and a novel NS5B resistance-associated substitution (RAS), L204F, representing 1.5% of the viral population at baseline, enriched to 71% and 91.6% during and after treatment failure, respectively. UDPS of NS5B from Pt2 indicated a mixed infection of approximately 1:5, GT1a:GT4d, at baseline and GT4d during failure. Phylogenetic analysis of NS5A sequences indicated no clustering of HCV strains from patients achieving SVR vs patients who relapsed. The mean genetic distance in NS5A sequences was 5.8%, while a lower genetic distance (3.1%) was observed in NS5B sequences. CONCLUSION: Results from these analyses confirm the importance of UDPS in the analysis of viral quasispecies variability and the identification of novel RASs potentially associated with DAA treatment failure in HCV GT4-infected patients.