Natural History of Hepatic and Extrahepatic Hepatitis C Virus Diseases and Impact of Interferon-Free HCV Therapy

Towards an HCV vaccine: an overview of the immunization strategies for eliciting an effective B-cell response

INTRODUCTION

Fifty-eight million people worldwide are chronically infected with hepatitis C virus (HCV) and are at risk of developing cirrhosis and hepatocellular carcinoma (HCC). Direct-acting antivirals are highly effective; however, they are burdened by high costs and the unchanged risk of HCC and reinfection, making prophylactic countermeasures an urgent medical need. HCV high genetic diversity is one of the main obstacles to vaccine development. The protective role of the humoral response directed against the HCV E2 glycoprotein is well established, and broadly neutralizing antibodies play a crucial role in effective viral clearance.

AREAS COVERED

This review explores the HCV targets and the different vaccination approaches, encompassing different expression systems, antigen selection strategies, and delivery methods, focusing on those aimed at eliciting a broad and effective humoral response. Our search criteria included the keywords 'HCV,' 'Hepatitis C,' and 'vaccine' using publicly available databases. Following the screening, 54 papers were selected.

EXPERT OPINION

The investigation of novel vaccine platforms beyond traditional approaches is necessary. While progress has been made in this direction, continued investigations on the HCV virology, immunology, and vaccinology are essential to surmount associated obstacles, heling in the development of an HCV vaccine that can benefit the global public health.

Risk factors and clinical outcomes in patients with HCV eradication by direct-acting antivirals: a systematic review and meta-analysis

BACKGROUND

In hepatitis C patients with sustained virologic response (SVR) achieved after direct-acting antivirals (DAAs), the incidence of adverse clinical outcomes can be reduced but not completely eliminated. This meta-analysis aims at estimating the incidence of clinical outcomes in hepatitis C patients after achieving SVR with DAAs.

METHODS

Literature search was carried out in PubMed, Cochrane Library database, Web of Science, and Embase. The primary endpoint was the incidence of hepatocellular carcinoma (HCC) occurrence, HCC recurrence, decompensated cirrhosis, and liver-related mortality, following DAA-induced elimination of hepatitis C virus (HCV). Subgroup analyses were performed according to age, gender, comorbidities, region, fibrosis stage, presence of decompensation, duration of follow-up, start point of follow-up, and HCC treatment modality. Furthermore, meta-regression was performed to explore sources of high heterogeneity.

RESULTS

Finally, 132 articles were included in our study. The pooled HCC occurrence rate was 1.50/100 person-years (95% CI, 1.35-1.65), HCC recurrence rate was 17.00/100 person-years (95% CI, 13.83-20.42), decompensation rate was 0.30/100 person-years (95% CI, 0.16-0.48), and liver-related mortality was 0.32/100 person-years (95% CI, 0.14-0.56). Meta-regression showed that duration of follow-up and fibrosis grade were important contributors to HCC occurrence. Age, start point of follow-up, and duration of follow-up were important contributors to HCC recurrence rate.

CONCLUSION

Patients with DAA-induced HCV elimination remain at risk for adverse outcomes, particularly those with cirrhosis and HCC history. The exposure to adverse outcomes tended to decrease over time, and the frequency and intensity of follow-up might be reduced in the future, which will require new scoring models to identify these individuals.

Hepatitis C testing and linkage to care in a safety-net hospital emergency department

BACKGROUND AND PURPOSE

In 2020, the CDC expanded hepatitis C (HCV) screening recommendations to include universal screening for persons 18 and older. We implemented universal screening in the emergency department (ED) within a safety-net health system. We aimed to measure HCV prevalence and linkage to care (LTC) outcomes in the ED and compare them to the outpatient clinics within the same health system.

METHODS

Patients aged 18-79 without HCV qualified for screening. We measured prevalence of both anti-HCV+ (exposure) and HCV RNA+ (active infection). Those with active HCV were flagged for LTC and their charts were followed for outcomes. HCV prevalence and LTC in the ED were compared to those in outpatient clinics over the same time.

RESULTS

9511 patients were screened for HCV from 2019 to 2022 in the ED. 6.9 % (659) were anti-HCV+. 54.9 % (320 of 582) of anti-HCV+ individuals or 3.4 % of those screened (320 of 9511) were HCV RNA+. The LTC rate was 24.1 % (77 of 320) and a total of 56 individuals (17.8 % of all HCV RNA+ ED patients, 72.7 % of those linked) initiated treatment. HCV prevalence was higher in the ED compared to the outpatient clinic setting. Demographics and LTC rates also significantly differed between these two cohorts.

CONCLUSIONS

We identified a higher HCV prevalence in the ED relative to the outpatient clinic setting and significant need for improvement in LTC and HCV treatment initiation. Our findings suggest universal screening is an important tool to diagnose HCV infections but may require novel strategies for improved LTC and treatment initiation.

Treatment of chronic hepatitis C infection: strategies to address poor therapy adherence

INTRODUCTION

Non-adherence to any therapy may be related to skipping drug doses, discontinuation of therapy, or loss of follow-up. It leads to the ineffectiveness of treatment, which is associated with obvious individual health losses, significant social and financial costs, and, in the case of infectious diseases, epidemiological consequences resulting from the possibility of further spread of infection.

AREAS COVERED

This review article analyses the causes and effects of non-adherence to treatment in patients infected with the hepatitis C virus (HCV). It also presents strategies to reduce the risk of non-adherence, which can be implemented by simplifying the treatment process, improving the flow of information between the doctor and the patient, as well as improving patients' knowledge about hepatitis C infection, and facilitating the understanding of the risks associated with non-adherence.

EXPERT OPINION

Since the treatment of HCV infections is highly effective in almost all patients who complete medication, no new drugs are to be expected in the coming years. Therefore, the primary attention in the global elimination of HCV will be focused on screening programs, improving the availability of drugs, and reducing the risk of non-adherence.

Metabolic dysfunction-associated steatotic liver disease (MASLD): Exploring systemic impacts and innovative therapies

Metabolic dysfunction-associated steatotic liver disease (MASLD), which includes the inflammatory subtype metabolic dysfunction-associated steatohepatitis, is a prominent cause of chronic liver disease with systemic effects. Insulin resistance, obesity, and dyslipidaemia produce MASLD in over 30 % of adults. It is a global health issue. From MASLD to MASH, hepatic inflammation and fibrosis grow, leading to cirrhosis, hepatocellular cancer, and extrahepatic complications such CVD, CKD, and sarcopenia. Effects of MASLD to MASH are mediated through mechanisms that include inflammation, oxidative stress, dysbiosis, and predisposition through genetic makeup. Advances in diagnostic nomenclature in the past few years have moved the emphasis away from NAFLD to MASLD, focusing on the metabolic etiology and away from the stigma of an alcoholic-related condition. Epidemiological data show a large geographical variability and increasing prevalence in younger populations, particularly in regions with high carbohydrate-rich diets and central adiposity. Lifestyle modification is considered as the main management of MASLD currently. This may include dietary intervention, exercise, and weight loss management. Pharmaceutical management is primarily aimed at metabolic dysfunction with promising findings for GLP-1 receptor agonists, pioglitazone and SGLT-2 inhibitors, which can correct both hepatic and systemic outcome. However, it still depends on well-integrated multidisciplinary care models by considering complex relationships between MASLD and its effects on extrahepatic organs. Determining complications at an early stage; developing precision medicine strategies; exploring new therapeutic targets will represent crucial factors in improving their outcomes. This review discuss the systemic nature of MASLD and calls for multiple collaborations to reduce its far-reaching health impacts and our quest for understanding its pathological mechanisms. Thus, collective efforts that are required to address MASLD are under the public health, clinical care, and research angles toward effectively containing its rapidly increasing burden.

Prevalence of hepatitis C, hepatitis B and HIV and their therapeutic management in a French public psychiatric hospital

INTRODUCTION

Several studies suggest that the prevalence of hepatitis C, hepatitis B and HIV are higher in psychiatric patients than in the general population; however, few French studies have been published. The aims of this study were to determine the seroprevalence of the three viruses, describe the profile of infected patients and evaluate the initiation of antiviral treatment in a population of patients hospitalized in a psychiatric hospital.

METHOD

Between January and October 2020, screening for hepatitis C virus, hepatitis B virus and HIV was systematically offered to all patients admitted to the intersectoral reception and orientation unit of a psychiatric hospital. If serology was positive, viral load was automatically determined from the same blood sample. As direct-acting antivirals (DAAs) are not financed "in addition" to hospital charges, it was decided a priori to start treatment for HCV immediately before discharge.

RESULTS

Between January 7 and October 1, 2020, 407 patients accepted screening. Of these patients, 17 (4.2%; 95% CI: 2.2-6.1%) were anti-HCV positive and two were anti-HIV+/anti-HCV- (0.49%). HCV RNA was detectable in 9/17 anti-HCV+ patients, with a prevalence of infection of 2.2% (CI: 0.8-3.6%). Drug use was identified in 16 anti-HCV+ patients (94%), ten with active drug use. Of the nine viraemic patients, only four received a prescription for DAA treatment at the end of hospitalization, and only one was followed up by his general practitioner with the confirmation of virological cure three months after treatment cessation. No patient tested positive for hepatitis B surface antigen, but 3% had serological markers indicating HBV past infection. The anti-HBV vaccination coverage rate was only 39% in the entire population and only 41% for patients with a history of drug use.

CONCLUSION

Our study confirms that the prevalence of HCV infection is significantly higher in the psychiatric population than in the general population. By far, the main risk factor for HCV infection is drug use. This justifies the systematic performance of regular screening in this population. The way in which DAAs are financed in psychiatric hospitals seems to be a major obstacle to the initiation of treatment for chronic HCV infection during hospitalization and therefore to the elimination of HCV infection in the psychiatric population.

Chronic Hepatitis C Infection Treated with Direct-Acting Antiviral Agents and Occurrence/Recurrence of Hepatocellular Carcinoma: Does It Still Matter?

Hepatitis C virus (HCV) infection is a significant risk factor for liver cirrhosis and hepatocellular carcinoma (HCC). Traditionally, the primary prevention strategy for HCV-associated HCC has focused on removing infection through antiviral regimes. Currently, highly effective direct-acting antivirals (DAAs) offer extraordinary success across all patient categories, including cirrhotics. Despite these advancements, recent studies have reported that even after sustained virologic response (SVR), individuals with advanced liver disease/cirrhosis at the time of DAA treatment may still face risks of HCC occurrence or recurrence. Based on this premise, this review tries to shed light on the multiple mechanisms that establish a tumorigenic environment, first, during chronic HCV infection and then, after eventual viral eradication by DAAs. Furthermore, it reviews evidence reported by recent observational studies stating that the use of DAAs is not associated with an increased risk of HCC development but rather, with a significantly lower chance of liver cancer compared with DAA-untreated patients. In addition, it seeks to provide some practical guidance for clinicians, helping them to manage HCC surveillance of patients who have achieved SVR with DAAs.

Anti-viral and Apoptotic Induction of m-TOR Inhibitor Drugs against Hepatitis C Virus Activity and Hepatocellular Carcinoma Cell Line: In vitro and in silico

OBJECTIVE

This study investigated the potential of m-TOR inhibitor drugs (sirolimus, everolimus, and tacrolimus) in combating both hepatocellular carcinoma (HCC) and hepatitis C virus (HCV) replication.

METHODS

After treating HepG2 and PBMCs with the mammalian target of Rapamycin (m-TOR) inhibitors drugs; sirolimus, everolimus, and tacrolimus at different concentrations (1, 5, and 10 µM/µl), cell proliferation was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Antioxidant activities (total antioxidant, glutathione S-transferase, and glutathione reductase), Fas-ligand level, tumor necrosis factor-α (TNF-α) level, caspase-3, -8, and -9 activities, and cell cycle analysis were measured. quantitative Real-time PCR, colony forming assay, molecular docking studies after infection of PBMCs with 1 ml (1.5 × 106 HCV) serum then incubated with m-TOR inhibitor drugs at their respective IC50 concentrations.

RESULTS

In HepG2 cells, treatment with these inhibitors resulted in suppressed cell viability, increased dead cell accumulation, and enhanced apoptotic signaling through elevated Fas-ligand and caspase activities. Additionally, cell cycle analysis revealed arrest in G0/G1 and G2/M phases, further hindering HCC progression. Furthermore, m-TOR inhibitor drugs significantly reduced HCV viral load and colony formation in infected PBMCs. This antiviral effect was accompanied by decreased TNF-α activity, suggesting potential modulation of the inflammatory response associated with HCV infection. Molecular docking studies provided theoretical support for these findings, with Sovaldi demonstrating the highest binding affinity towards key HCV targets compared to other m-TOR inhibitors. This suggests its potential as a potent HCV inhibitor, while also highlighting the potential of exploring m-TOR inhibitors for future HCV treatment development.

CONCLUSION

Overall, this study provides encouraging evidence for the potential of m-TOR inhibitor drugs as promising therapeutic agents for both HCC and HCV, warranting further investigation and optimization for clinical applications.

Effectiveness of Ledipasvir-Sofosbuvir 12 Weeks After Hepatitis C Virus Genotype 1 Infection and the Factors Associated With Sustained Virologic Response: A Retrospective Study

BACKGROUND

The combination of ledipasvir and sofosbuvir (LDV/SOF) has been licensed to treat genotype 1 hepatitis C virus infection (HCV) with a 12-week regimen. However, there is scant data from Yemen regarding this combination regimen. Here, we investigate sustained virologic responses (SVR) 12 weeks after HCV treatment with LDV/SOF regimens and the factors that contribute to SVR failure.

MATERIAL AND METHOD

A retrospective cross-sectional study was conducted at Althora General Hospital in Ibb, Yemen, from June 1, 2019, to October 31, 2022, on 53 cases with HCV genotype 1 infection who received combined therapy of LDV/SOF and completed treatment for 12 weeks. The clinical characteristics and treatment follow-up were obtained from patient medical records. Factors associated with SVR failure were investigated in univariate analysis with odds ratio (OR) and 95% confidence interval (CI).

RESULT

The mean age was 50 ± 15.3 years, and most cases were female (n=36, 67.9%). Comorbidities were diabetes, hypertension, and fatty liver, which were represented in 12 (22.6%), nine (17.0%), and eight (15.1%) cases, respectively. A total of 13 (24.5%) patients had compensated liver cirrhosis, while the remaining 40 patients (75.5%) were non-cirrhotic healthy individuals. The baseline viral load (HCV RNA) was more than 800000 IU/mL in 21 patients (39.6%). Early virological response (ERV) was achieved in 51 patients (96.2%). After treatment, 46 of the patients (86.8%) achieved SVR at Week 12, while failure occurred in two patients (3.8%) and relapse occurred in five patients (9.4%). Blood liver enzymes, including alanine aminotransferase, aspartate aminotransferase, and alkaline phosphatase, returned to normal, with statistically significant improvements in non-cirrhotic healthy persons than compensated liver cirrhosis individuals (p= 0.006, 0.006, and 0.010; respectively). Factors associated with SVR failure were older age (OR:1.13; 95% CI: 1.03-1.30, p=0.009), presence of liver cirrhosis (OR: 5.48; 95% CI: 1.04-28.98, p=0.031), having diabetes (OR: 6.33; 95% CI: 1.19-37.93, p= 0.019), baseline higher viral load (OR: 2.27; 95% CI: 0.45-12.73, p<0.001), and not achieving EVR (OR:7.63; 95% CI: 3.77- 17.78, p= 0.009).

CONCLUSION

In this study, we found that LDV/SOF regimens are effective against HCV genotype one infection, allowing for the expansion of 12-week treatment for suitable patients in clinical settings. Additionally, older age, liver cirrhosis, diabetes, higher pretreatment viral load, and non-completion of EVR were associated with SVR failure. However, due to the small number of HCV genotype 1 infected individuals in this study, more corporate data is required to get a clear conclusion.

Personalized care approaches to hepatitis C therapy: recent advances and future directions

INTRODUCTION

The introduction of direct-acting antivirals (DAAs) has significantly transformed the therapeutic landscape for chronic C hepatitis virus (HCV) infection. However, there is still room for further improvement in optimizing therapy efficacy and minimizing adverse effects.

AREAS COVERED

This review is devoted to the rationale for adopting a personalized approach to HCV therapy. Specifically, we explore the role of host-related factors, such as sex or the presence of comorbidities. We thoroughly examine the implications of commonly encountered comorbidities, including HIV infection, chronic renal disease, liver cirrhosis, and other chronic viral hepatitis infections. Additionally, we discuss the prevalent drug-to-drug interactions between DAAs and other medications, while providing guidance on their management. Finally, we investigate viral-related issues that can influence treatment outcomes, such as viral genotype, quasi-species, and the presence of resistance-associated mutations.

EXPERT OPINION

Despite pivotal trials demonstrating efficacy rates exceeding 90% for currently available DAA regimens, there are still opportunities to optimize therapy outcomes and tailor treatment to each patient. This can be achieved through a meticulous evaluation of the patient's specific clinical conditions and comorbidities, a vigilant approach to manage potential drug interactions, and diligent patient follow-up.

Protein Induced by Vitamin K Absence or Antagonist-II Versus Alpha-Fetoprotein in the Diagnosis of Hepatocellular Carcinoma: A Systematic Review With Meta-Analysis

Background

Protein induced by vitamin K absence or antagonist-II (PIVKA-II) and α-fetoprotein (AFP) are promising tumor markers for the diagnosis of hepatocellular carcinoma (HCC). Yet, their diagnostic performance differs throughout HCC investigations. The aim of this meta-analysis was to assess the effectiveness of PIVKA-II and AFP in the diagnosis of HCC.

Methods

A systematic literature search was performed to identify relevant studies from eight databases, which were published up to February 2023, in order to compare the diagnostic performance of PIVKA-II and AFP for HCC. Pooled sensitivity and specificity were calculated. Summary receiver operating characteristic (SROC) curve was performed to assess the diagnostic accuracy of each biomarker.

Results

Fifty-three studies were identified. The pooled sensitivity (95% confidence interval (CI)) of PIVKA-II and AFP was 0.71 (0.70 - 0.72) and 0.64 (0.63 - 0.65), respectively in diagnosis of HCC, and the corresponding pooled specificity (95% CI) was 0.90 (0.89 - 0.90) and 0.87 (0.87 - 0.88), respectively. The area under the ROC curve (AUC) of PIVKA-II and AFP was 0.89 (0.88 - 0.90) and 0.78 (0.77 - 0.79), respectively. Subgroup analysis demonstrated that PIVKA-II presented higher AUC values compared to AFP in terms of ethnic group (African, European, Asian, and American patients), etiology (mixed-type HCC, hepatitis C virus (HCV)-related, and hepatitis B virus (HBV)-related) and sample size of cases (≤ 100 and > 100).

Conclusion

This study reveals that PIVKA-II is a promising biomarker for identifying and tracking HCC, exhibiting greater accuracy than AFP. Our findings indicate that PIVKA-II outperforms AFP in detecting HCC across diverse racial groups and sample sizes, as well as in cases of HBV-related, HCV-related, or mixed-etiology HCC.

The Role of the Microbiota Gut-Liver Axis during HCV Chronic Infection: A Schematic Overview

Hepatitis C virus (HCV) still represents one of the most important worldwide health care problems. Since 2011, direct-acting antiviral (DAA) drugs have increased the number of people who have achieved a sustained virological response (SVR). Even if the program to eradicate HCV by 2030 is still ongoing, the SARS-CoV-2 pandemic has created a delay due to the reallocation of public health resources. HCV is characterized by high genetic variability and is responsible for hepatic and extra-hepatic diseases. Depending on the HCV genotype/subtype and comorbidities of patients, tailored treatment is necessary. Recently, it has been shown that liver damage impacts gut microbiota, altering the microbial community (dysbiosis) during persistent viral replication. An increasing number of studies are trying to clarify the role of the gut-liver axis during HCV chronic infection. DAA therapy, by restoring the gut microbiota equilibrium, seems to improve liver disease progression in both naïve and treated HCV-positive patients. In this review, we aim to discuss a snapshot of selected peer-reviewed papers concerning the interplay between HCV and the gut-liver axis.

The curing regimens of HCV: A SWOT analysis

The development of direct-acting antivirals (DAA) has revolutionized the treatment of chronic hepatitis C, enabling cure of hepatitis C virus (HCV) infection in more than 95% of cases. There are essentially no contraindications, so almost any patient can now be successfully treated. The result is the prevention or amelioration of cirrhosis, hepatocellular carcinoma (HCC), and extrahepatic manifestations. Consequently, the 2020 Nobel Prize in Medicine and Physiology was awarded for the discovery of HCV. Due to the high efficacy of therapy, even global HCV elimination is conceivable even without a vaccine. Here, we would like to venture a SWOT analysis of current HCV therapies aimed at HCV elimination.

Immune Activation Induces Telomeric DNA Damage and Promotes Short-Lived Effector T Cell Differentiation in Chronic HCV Infection

BACKGROUND AND AIMS

Hepatitis C virus (HCV) leads to a high rate of chronic infection and T cell dysfunction. Although it is well known that chronic antigenic stimulation is a driving force for impaired T cell functions, the precise mechanisms underlying immune activation-induced T cell dysfunctions during HCV infection remain elusive.

APPROACH AND RESULTS

Here, we demonstrated that circulating CD4⁺ T cells from patients who are chronically HCV-infected exhibit an immune activation status, as evidenced by the overexpression of cell activation markers human leukocyte antigen-antigen D-related, glucose transporter 1, granzyme B, and the short-lived effector marker CD127^- killer cell lectin-like receptor G1⁺ . In contrast, the expression of stem cell-like transcription factor T cell factor 1 and telomeric repeat-binding factor 2 (TRF2) are significantly reduced in CD4⁺ T cells from patients who are chronically HCV-infected compared with healthy participants (HP). Mechanistic studies revealed that CD4⁺ T cells from participants with HCV exhibit phosphoinositide 3-kinase/Akt/mammalian target of rapamycin signaling hyperactivation on T cell receptor stimulation, promoting proinflammatory effector cell differentiation, telomeric DNA damage, and cellular apoptosis. Inhibition of Akt signaling during T cell activation preserved the precursor memory cell population and prevented inflammatory effector cell expansion, DNA damage, and apoptotic death. Moreover, knockdown of TRF2 reduced HP T cell stemness and triggered telomeric DNA damage and cellular apoptosis, whereas overexpression of TRF2 in CD4 T cells prevented telomeric DNA damage.

CONCLUSIONS

These results suggest that modulation of immune activation through inhibiting Akt signaling and protecting telomeres through enhancing TRF2 expression may open therapeutic strategies to fine tune the adaptive immune responses in the setting of persistent immune activation and inflammation during chronic HCV infection.

Partial restoration of immune response in Hepatitis C patients after viral clearance by direct-acting antiviral therapy

BACKGROUND & AIMS

HCV CD4+ and CD8+ specific T cells responses are functionally impaired during chronic hepatitis C infection. DAAs therapies eradicate HCV infection in more than 95% of treated patients. However, the impact of HCV elimination on immune responses remain controversial. Here, we aimed to investigate whether HCV cure by DAAs could reverse the impaired immune response to HCV.

METHODS

We analyzed 27 chronic HCV infected patients undergoing DAA treatment in tertiary care hospital, and we determined the phenotypical and functional changes in both HCV CD8+ and CD4+ specific T-cells before and after viral clearance. PD-1, TIM-3 and LAG-3 cell-surface expression was assessed by flow cytometry to determine CD4+ T cell exhaustion. Functional responses to HCV were analyzed by IFN-Ɣ ELISPOT, intracellular cytokine staining (IL-2 and IFN-Ɣ) and CFSE-based proliferation assays.

RESULTS

We observed a significant decrease in the expression of PD-1 in CD4+ T-cells after 12 weeks of viral clearance in non-cirrhotic patients (p = 0.033) and in treatment-naive patients (p = 0.010), indicating a partial CD4 phenotype restoration. IFN-Ɣ and IL-2 cytokines production by HCV-specific CD4+ and CD8+ T cells remained impaired upon HCV eradication. Finally, a significant increase of the proliferation capacity of both HCV CD4+ and CD8+ specific T-cells was observed after HCV elimination by DAAs therapies.

CONCLUSIONS

Our results show that in chronically infected patients HCV elimination by DAA treatment lead to partial reversion of CD4+ T cell exhaustion. Moreover, proliferative capacity of HCV-specific CD4+ and CD8+ T cells is recovered after DAA's therapies.

Direct antiviral agents in hepatitis C virus related liver disease: Don't count the chickens before they're hatched

Since molecules with direct-acting antiviral (DAA) became available, the landscape of the treatment of hepatitis C virus (HCV) infection has completely changed. The new drugs are extremely effective in eradicating infection, and treatment is very well tolerated with a duration of 8-12 wk. This review aims to report the outstanding clinical benefits of DAA and to highlight their critical disadvantages, identifying some clinically relevant hot topics. First, do the rates of virological response remain as high when patients with more advanced cirrhosis are considered? Large studies have shown slightly lower but still satisfactory rates of response in these patients. Nevertheless, modified schedules with an extended treatment duration and use of ribavirin may be necessary. Second, does the treatment of HCV infection affect the risk of occurrence and recurrence of liver cancer? Incidence is reduced after viral eradication but remains high enough to warrant periodic surveillance for an early diagnosis. In contrast, the risk of recurrence seems to be unaffected by viral clearance; however, DAA treatment improves survival because of the reduced risk of progression of liver disease. Third, can HCV treatment also have favorable effects on major comorbidities? HCV eradication is associated with a reduced incidence of diabetes, an improvement in glycemic control and a decreased risk of cardiovascular events; nevertheless, a risk of hypoglycemia during DAA treatment has been reported. Finally, is it safe to treat patients with HCV/ hepatitis B virus (HBV) coinfection? In this setting, HCV is usually the main driver of viral activity, while HBV replication is suppressed. Because various studies have described HBV reactivation after HCV clearance, a baseline evaluation for HBV coinfection and a specific follow-up is mandatory.

Hepatitis C Virus

Hepatitis C virus (HCV) is the most common bloodborne pathogen in the United States, chronically affecting approximately 2.4 million Americans, most of whom are unaware of the infection. Highly effective, well-tolerated therapies are now available with markedly simplified treatment algorithms. Eradication of HCV is a national goal. Increased efforts to extend access to treatment to populations that traditionally are difficult to treat, such as persons who inject drugs, are critical to achieving eradication. Given the magnitude of the disease burden, an increased role of primary care providers in screening, patient stratification, and treatment will be needed.

Adaptive Immune Response against Hepatitis C Virus

A functional adaptive immune response is the major determinant for clearance of hepatitis C virus (HCV) infection. However, in the majority of patients, this response fails and persistent infection evolves. Here, we dissect the HCV-specific key players of adaptive immunity, namely B cells and T cells, and describe factors that affect infection outcome. Once chronic infection is established, continuous exposure to HCV antigens affects functionality, phenotype, transcriptional program, metabolism, and the epigenetics of the adaptive immune cells. In addition, viral escape mutations contribute to the failure of adaptive antiviral immunity. Direct-acting antivirals (DAA) can mediate HCV clearance in almost all patients with chronic HCV infection, however, defects in adaptive immune cell populations remain, only limited functional memory is obtained and reinfection of cured individuals is possible. Thus, to avoid potential reinfection and achieve global elimination of HCV infections, a prophylactic vaccine is needed. Recent vaccine trials could induce HCV-specific immunity but failed to protect from persistent infection. Thus, lessons from natural protection from persistent infection, DAA-mediated cure, and non-protective vaccination trials might lead the way to successful vaccination strategies in the future.