Viral dynamics of hepatitis C early after orthotopic liver transplantation: evidence for rapid turnover of serum virions

Innate immune surveillance of the circulation: A review on the removal of circulating virions from the bloodstream

Many viruses utilize the lymphohematogenous route for dissemination; however, they may not freely use this highway unchecked. The reticuloendothelial system (RES) is an innate defense system that surveys circulating blood, recognizing and capturing viral particles. Examination of the literature shows that the bulk of viral clearance is mediated by the liver; however, the precise mechanism(s) mediating viral vascular clearance vary between viruses and, in many cases, remains poorly defined. Herein, we summarize what is known regarding the recognition and capture of virions from the circulation prior to the generation of a specific antibody response. We also discuss the consequences of viral capture on viral pathogenesis and the fate of the captor cell. Finally, this understudied topic has implications beyond viral pathogenesis, including effects on arbovirus ecology and the application of virus-vectored gene therapies.

Modeling hepatitis C virus kinetics during liver transplantation reveals the role of the liver in virus clearance

While the liver, specifically hepatocytes, are widely accepted as the main source of hepatitis C virus (HCV) production, the role of the liver/hepatocytes in clearance of circulating HCV remains unknown. Frequent HCV kinetic data were recorded and mathematically modeled from five liver transplant patients throughout the anhepatic (absence of liver) phase and for 4 hr post-reperfusion. During the anhepatic phase, HCV remained at pre-anhepatic levels (n = 3) or declined (n = 2) with t_1/2~1 hr. Immediately post-reperfusion, virus declined in a biphasic manner in four patients consisting of a rapid decline (t_1/2 = 5 min) followed by a slower decline (t_1/2 = 67 min). Consistent with the majority of patients in the anhepatic phase, when we monitored HCV clearance at 37°C from culture medium in the absence/presence of chronically infected hepatoma cells that were inhibited from secreting HCV, the HCV t_1/2 in cell culture was longer in the absence of chronically HCV-infected cells. The results suggest that the liver plays a major role in the clearance of circulating HCV and that hepatocytes may be involved.

Overview of Immobilized Enzymes' Applications in Pharmaceutical, Chemical, and Food Industry

The use of immobilized enzymes in industry is becoming a routine process for the manufacture of many key compounds in the pharmaceutical, chemical, and food industry. Some enzymes like lipases are naturally robust and efficient, can be used for the production of many different molecules, and have found broad industrial applications. Some more specific enzymes, like transaminases, have required protein engineering to become suitable for applications in industrial manufacture. For all enzymes, the possibility to be immobilized and used in a heterogeneous form brings important industrial and environmental advantages such as simplified downstream processing or continuous process operations. Here, we present a series of large-scale applications of immobilized enzymes with benefits for the food, chemical, pharmaceutical, cosmetics, and medical device industries, some of them hardly reported before.

Hepatitis C genotype change after transplantation utilizing hepatitis C positive donor organs

A shortage in organs for transplantation has led to the increased use of hepatitis C (HCV) infected donor organs for solid organ transplant recipients infected with HCV. However, the donor HCV genotype is not routinely checked or known prior to transplant. Here, we report 4 cases of genotype conversion after transplantation in patients receiving HCV infected donor organs. This change in genotype may potentially impact HCV progression as well as treatment choice for these patients.

Efficacy and Safety of a Steroid-Free Immunosuppressive Regimen after Liver Transplantation for Hepatocellular Carcinoma

Background/Aims

We aimed to evaluate the efficacy and safety of an immunosuppressive regimen without steroids after liver transplantation (LT) for hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC).

Methods

Sixty-six HCC patients who underwent an immunosuppressive regimen without steroids after LT were enrolled in the steroid-free group. The preoperative characteristics and postoperative outcomes of these patients were compared with those of 132 HCC recipients who were placed on an immunosuppressive regimen using steroids (steroid group). The incidence of acute rejection, HBV recurrence, infection, and new-onset diabetes mellitus and the overall and tumor-free survival rates were compared between the two groups.

Results

Differences were not observed in the 1-year (83.3% vs 97.0%, p=0.067), 3-year (65.4% vs 75.8%, p=0.067) or 5-year (56.3% vs 70.7%, p=0.067) patient survival rates or in the 1-year (62.1% vs 72.7%, p=0.067), 3-year (49.8% vs 63.6%, p=0.067) or 5-year (48.6% vs 63.6%, p=0.067) tumor-free survival rates between the two groups, respectively. In the steroid-free group, the patients who fulfilled the Milan criteria had higher overall and tumor-free survival rates than those in the steroid group (p<0.001). The prevalence of HBV recurrence (3.0% vs 13.6%, p=0.02) was significantly lower in the steroid-free group compared with the steroid group.

Conclusions

After LT, an immunosuppressive regimen without steroids could be a safe and feasible treatment for HBV-related HCC patients, thus resulting in the reduction of HBV recurrence. Based on the observed survival rates, patients who fulfill the Milan criteria may derive benefits from steroid-free immunosuppression.

Negativization of viremia prior to liver transplant reduces early allograft dysfunction in hepatitis C-positive recipients

Although early allograft dysfunction (EAD) negatively impacts survival from the first months following liver transplantation (LT), direct-acting antiviral agents (DAAs) have revolutionized hepatitis C virus (HCV) therapy. We investigated the EAD definition best predicting 90-day graft loss and identified EAD risk factors in HCV-positive recipients. From November 2002 to June 2016, 603 HCV-positive patients (hepatocellular carcinoma, 53.4%) underwent a first LT with HCV-negative donors. The median recipient Model for End-Stage Liver Disease (MELD) score was 15, and the median donor age was 63 years. At LT, 77 (12.8%) patients were HCV RNA negative; negativization was achieved and maintained by pre-LT antiviral therapy (61 patients) or pre-LT plus a pre-emptive post-LT course (16 patients); 60 (77.9%) patients received DAAs and 17 (22.1%) interferon. We compared 3 different EAD definitions: (1) bilirubin ≥ 10 mg/dL or international normalized ratio ≥ 1.6 on day 7 after LT or aspartate aminotransferase or alanine aminotransferase > 2000 IU/L within 7 days of LT; (2) bilirubin > 10 mg/dL on days 2-7 after LT; and (3) MELD ≥ 19 on day 5 after LT. EAD defined by MELD ≥ 19 on day 5 after LT had the lowest negative (0.1) and the highest positive (1.9) likelihood ratio to predict 90-day graft loss. At 90 days after LT, 9.2% of recipients with EAD lost their graft as opposed to 0.7% of those without EAD (P < 0.001). At multivariate analysis, considering variables available at LT, MELD at LT of >25 (OR = 7.4) or 15-25 (OR = 3.2), graft macrovesicular steatosis ≥ 30% (OR = 6.7), HCV RNA positive at LT (OR = 2.7), donor age > 70 years (OR = 2.0), earlier LT era (OR = 1.8), and cold ischemia time ≥ 8 hours (OR = 1.8) were significant risk factors for EAD. In conclusion, in HCV-positive patients, MELD ≥ 19 on day 5 after LT best predicts 90-day graft loss. Preventing graft infection by pre-/peri-LT antiviral therapy reduces EAD incidence and could be most beneficial in high-MELD patients and recipients of suboptimal grafts. Liver Transplantation 23 915-924 2017 AASLD.

Predictors of Poor Prognosis in Recurrent Hepatitis C After Liver Transplantation

BACKGROUND

Hepatitis C is a common indication for liver transplantation (LT). Hepatitis C virus (HCV) recurrence is universal in viremic patients. This recurrence is frequently very aggressive, with graft loss in less than 5 years. Our aim is to detect which factors are related to worse fibrosis at 1 year post-LT.

PATIENTS AND METHODS

Records of all HCV-positive transplanted patients in Hospital Universitario Nuestra Señora de la Candelaria from 1996 to 2014 were collected. The variables analyzed were donor and recipient age and gender, hypertension, diabetes, viral genotype, viral load at LT, hepatocellular carcinoma in the explant, anticoagulation or antiplatelet treatment, year of transplantation, and mean levels of tacrolimus in the first month. Severe recurrence was defined as fibrosis F3 by biopsy, liver stiffness > 9.5 kPa by transient elastography, or hepatic venous pressure gradient > 5 mm Hg at 1 year post-LT. Univariate and multivariate analyses were performed.

RESULTS

From a sample of 112 patients, 88 patients met inclusion criteria. Mean recipient age was 52.8 ± 8.0 years and 70.5% were men. Mean donor age was 46.4 ± 16.1 years and 59.1% were men. Severe recurrence occurred in 23.9%. Univariate analyses showed 3 variables were statistically significant: donor age (P = .03), recipient age (P = .008), and presence of hepatocellular carcinoma (P = .01). Only the 2 first variables remained significant in the multivariate model (P = .009 and P = .044 respectively). Hepatocellular carcinoma was probably related to older recipients becoming a confounding factor.

CONCLUSIONS

In our study, donor and recipient age both conferred a worse prognosis in terms of fibrosis progression in patients with liver transplant due to HCV.

Hepatitis C virus may have an entero-hepatic cycle which could be blocked with ezetimibe

Hepatitis C virus can lead to chronic infection, cirrhosis and hepatocellular carcinoma. With more than 170 million people infected worldwide, eradication remains a challenge even with the revolutionary current direct antiviral agents (DAAs). The risk of resistance, the safety profile in some populations, the genotype specificity and the high price of current DAAs explain why there is still interest in developing host targeting agents (HTA) that may help overcome some of these difficulties. Specifically, targeting the entry of HCV to the cell seems like a promising strategy. Recently it has been shown that the cholesterol transporter NPC1L1, a protein located in the small bowel epithelium and in the canalicular membrane of the hepatocyte is also an HCV receptor. Just as this protein is key in the entero-hepatic cycle of cholesterol, we hypothesize that there is an entero-hepatic cycle of HCV that could be disrupted by blocking NPC1L1 with ezetimibe, an already approved and readily available safe drug. Ezetimibe, either alone or in combination with DAAs, could decrease relapse rates, reduce resistance and even make treatments cheaper.

Acute cellular rejection versus recurrent hepatitis C after liver transplantation: Clinical and pathological features driving a rational diagnostic approach

AIM

The aim of our study was develop and validate an algorithm system based on morphological features for finding the differences between recurrent hepatitis C virus (HCV) and acute cellular rejection (ACR) in liver biopsies of HCV-transplanted patients.

METHODS

Two hundred and eighty-eight liver biopsies were analyzed from 121 patients transplanted for HCV. A diagnostic consensus was reached between clinicians and pathologists in 214 biopsies for the diagnosis of recurrent HCV or ACR. A random sample of 114 liver biopsies (derivation cohort) was taken to generate the diagnostic tree and was subsequently evaluated using the validation cohort in 100 liver biopsies by recursive partitioning analysis of morphological variables and time since transplantation.

RESULTS

The presence of endotheliitis together with a time of less than 6 weeks since LT definitely excluded recurrent HCV. After obtaining the regression tree, diagnostic accuracy was 96% and 93% in the derivation and validation cohort, respectively. Both cases surpassed the pathologist's original diagnosis, which had a diagnostic accuracy of 91% (P < 0.05, for both comparisons).

CONCLUSION

A recursive partitioning analysis of the morphological features in liver biopsies from HCV-transplanted patients may be useful for easily distinguishing between recurrent HCV and ACR.

Impact of alloimmune T cell responses on hepatitis C virus replication in liver transplant recipients

We investigated the influence of alloimmune T cell responses on hepatitis C virus (HCV) replication in HCV-infected patients after liver transplantation (LT). To monitor the immune-status in 27 HCV-infected LT recipients, we routinely performed mixed lymphocyte reaction (MLR) assays within 4 weeks after LT. HCV RNA titers in most patients fluctuated in inverse proportion to the stimulation index (SI) of anti-donor reactive T cells early after LT. Two weeks after LT, recipients with high HCV RNA titers (>1000 KIU/mL) displayed a significantly lower SI for anti-donor reactive T cells than recipients with low HCV RNA titers did (<1000 KIU/mL). An in vitro transwell assay mimicking the anatomical features of the interaction between HCV-infected hepatocytes and alloreactive T cells in allograft livers demonstrated that interferon (IFN)-γ was necessary to suppress HCV replication. This study proves the significant impact of alloimmune T cell responses on HCV replication in HCV-infected LT recipients.

Post-liver transplant hepatitis C virus recurrence: an unresolved thorny problem

Hepatitis C virus (HCV)-related cirrhosis represents the leading cause of liver transplantation in developed, Western and Eastern countries. Unfortunately, liver transplantation does not cure recipient HCV infection: reinfection universally occurs and disease progression is faster after liver transplant. In this review we focus on what happens throughout the peri-transplant phase and in the first 6-12 mo after transplantation: during this crucial period a completely new balance between HCV, liver graft, the recipient's immune response and anti-rejection therapy is achieved that will deeply affect subsequent outcomes. Nearly all patients show an early graft reinfection, with HCV viremia reaching and exceeding pre-transplant levels; in this setting, histological assessment is essential to differentiate recurrent hepatitis C from acute or chronic rejection; however, differentiating the two patterns remains difficult. The host immune response (mainly cellular mediated) appears to be crucial both in the control of HCV infection and in the genesis of rejection, and it is also strongly influenced by immunosuppressive treatment. At present no clear immunosuppressive strategy could be strongly recommended in HCV-positive recipients to prevent HCV recurrence, even immunotherapy appears to be ineffective. Nonetheless it seems reasonable that episodes of rejection and over-immunosuppression are more likely to enhance the risk of HCV recurrence through immunological mechanisms. Both complete prevention of rejection and optimization of immunosuppression should represent the main goals towards reducing the rate of graft HCV reinfection. In conclusion, post-transplant HCV recurrence remains an unresolved, thorny problem because many factors remain obscure and need to be better determined.

Maternal-fetal transmission of hepatitis C infection: what is so special about babies?

Children with hepatitis C virus infection often differ from adults regarding the rate of viral clearance, duration of infection, and the progression to cirrhosis. In the pediatric population, vertical transmission of hepatitis C virus infection from mother to infant is the most common route of infection. In the present review, we explore the factors that may influence the natural history of hepatitis C virus infection in children who acquire the infection through maternal-fetal transmission. There is particular focus on how viral diversity and the infant immune system may affect viral transmission. An enhanced understanding of maternal-fetal transmission of hepatitis C virus infection has the potential to affect effective drug and vaccine development for both children and adults.

The Role of mTOR Inhibitors in Liver Transplantation: Reviewing the Evidence

Despite the success of liver transplantation, long-term complications remain, including de novo malignancies, metabolic syndrome, and the recurrence of hepatitis C virus (HCV) and hepatocellular carcinoma (HCC). The current mainstay of treatment, calcineurin inhibitors (CNIs), can also worsen posttransplant renal dysfunction, neurotoxicity, and diabetes. Clearly there is a need for better immunosuppressive agents that maintain similar rates of efficacy and renal function whilst minimizing adverse effects. The mammalian target of rapamycin (mTOR) inhibitors with a mechanism of action that is different from other immunosuppressive agents has the potential to address some of these issues. In this review we surveyed the literature for reports of the use of mTOR inhibitors in adult liver transplantation with respect to renal function, efficacy, safety, neurological symptoms, de novo tumors, and the recurrence of HCC and HCV. The results of our review indicate that mTOR inhibitors are associated with efficacy comparable to CNIs while having benefits on renal function in liver transplantation. We also consider newer dosing schedules that may limit side effects. Finally, we discuss evidence that mTOR inhibitors may have benefits in the oncology setting and in relation to HCV-related allograft fibrosis, metabolic syndrome, and neurotoxicity.

Completely steroid-free immunosuppression in liver transplantation: a randomized study

INTRODUCTION

Corticosteroids (CS) have been standard immunosuppression to prevent and treat rejection. However, CS are associated with increased risk of infection, obesity, hypertension, hyperlipidemia, diabetes, and accelerated hepatitis C virus (HCV) recurrence post-orthotopic liver transplantation (OLT). This study assesses the safety and efficacy of CS-free immunosuppressive regimen in adult OLT.

METHODS

A two-yr, prospective, randomized study of CS with delayed withdrawal (CS) or CS-free regimen with basiliximab, tacrolimus, and enteric-coated mycophenolate sodium (EC-MPS) was performed in 39 patients (CS=20; CS-free=19). CS group received intra-operative methylprednisolone weaned by six months. HCV patients had HCV PCR pre-OLT and 0.5, one, three, and six months post-OLT. Protocol liver biopsies were performed at OLT, 2 and 24 wk post-OLT or when indicated.

RESULTS

Rejection occurred in two patients. Patient survival at one yr (100% vs. 95%), three yr (85% vs. 63%), and five yr (80% vs. 63%) post-OLT were similar between CS and CS-free group, respectively. Death-censored graft survival at one yr (100% vs. 95%), three yr (85% vs. 63%), and five yr (75% vs. 63%) were also similar. The risk of new-onset DM, hypertension, hypercholesterolemia, and weight gain was similar between groups.

CONCLUSION

CS avoidance with basiliximab, calcineurin inhibitor, and EC-MPS is safe and effective as CS- containing immunosuppression in adult OLT.

Safety and anti-HCV effect of prolonged intravenous silibinin in HCV genotype 1 subjects in the immediate liver transplant period

BACKGROUND & AIMS

Reinfection of the graft is the rule in patients with HCV cirrhosis undergoing liver transplantation, and HCV-RNA reaches pre-transplantation levels within the first month. Short-term intravenous silibinin monotherapy is safe and shows a potent in vivo anti-HCV effect. We aimed at evaluating the safety and antiviral effect of prolonged intravenous silibinin, started immediately before liver transplantation.

METHODS

Single centre, prospective, pilot study, to assess the safety and effect on HCV-RNA kinetics during at least 21 days of intravenous silibinin monotherapy (20 mg/kg/day) in 9 consecutive HCV genotype 1 subjects, in comparison to a control, non-treated group of 7 consecutive prior transplanted subjects under the same immunosuppressive regimen (basiliximab, steroids, delayed tacrolimus, micophenolate).

RESULTS

Intravenous silibinin led to significant, maintained and progressive HCV-RNA decreases (mean HCV-RNA drop at week 3, -4.1 ± 1.3 log(10)IU/ml), and lack of viral breakthrough during administration. Four patients (44%) reached negative HCV-RNA, maintained during silibinin treatment, vs. none in the control group, but HCV-RNA relapsed in all of them after a median of 21 days (16-28), following silibinin withdrawal. Partial responders to silibinin showed marked decreases in HCV-RNA when compared to controls, but lower than complete responders. There were no clinical adverse effects, and silibinin led to asymptomatic transient hyperbilirubinemia (week 2, 4.2 ± 2.2 vs. 2.5 ± 3.6 mg/dl; p=0.02).

CONCLUSIONS

Prolonged intravenous silibinin monotherapy was safe in the immediate liver transplantation period, leading to a potent and time dependent antiviral effect and lack of HCV-RNA breakthrough during administration. However, HCV-RNA rebounded after withdrawal, and silibinin monotherapy did not avoid reinfection of the graft.

Monoclonal antibodies against Hepatitis C genotype 3a virus like particle inhibit virus entry in cell culture system

The envelope protein (E1-E2) of Hepatitis C virus (HCV) is a major component of the viral structure. The glycosylated envelope protein is considered to be important for initiation of infection by binding to cellular receptor(s) and also known as one of the major antigenic targets to host immune response. The present study was aimed at identifying mouse monoclonal antibodies which inhibit binding of virus like particles of HCV to target cells. The first step in this direction was to generate recombinant HCV-like particles (HCV-LPs) specific for genotypes 3a of HCV (prevalent in India) using the genes encoding core, E1 and E2 envelop proteins in a baculovirus expression system. The purified HCV-LPs were characterized by ELISA and electron microscopy and were used to generate monoclonal antibodies (mAbs) in mice. Two monoclonal antibodies (E8G9 and H1H10) specific for the E2 region of envelope protein of HCV genotype 3a, were found to reduce the virus binding to Huh7 cells. However, the mAbs generated against HCV genotype 1b (D2H3, G2C7, E1B11) were not so effective. More importantly, mAb E8G9 showed significant inhibition of the virus entry in HCV JFH1 cell culture system. Finally, the epitopic regions on E2 protein which bind to the mAbs have also been identified. Results suggest a new therapeutic strategy and provide the proof of concept that mAb against HCV-LP could be effective in preventing virus entry into liver cells to block HCV replication.

Early viral load and recipient interleukin-28B rs12979860 genotype are predictors of the progression of hepatitis C after liver transplantation

There have been few detailed studies of viral kinetics after liver transplantation (LT), and conflicting data have been reported on viral loads and the severity of recurrent hepatitis C virus (HCV) disease. This long-term study aimed to examine (1) the impact of HCV RNA levels at specific points in time within the first year and (2) the influence of interleukin-28B (IL-28B) genotypes on patient outcomes and the severity of recurrent HCV disease. The viral loads were measured 2, 4, 12, 24, and 48 weeks after LT, and the recipient/donor IL-28B genotypes of 164 patients were determined. A Cox regression analysis showed that the viral load at week 2 was an independent negative predictor of recipient outcomes. A week 2 viral load ≥ 6.0 log(10) IU/mL was significantly associated with reduced patient survival. After a mean follow-up of 6.5 years, 21 of 164 patients (12.8%) developed a cholestatic type of HCV recurrence and/or rapidly progressed to cirrhosis within 1 year. A multivariate binary regression analysis showed that HCV viremia at week 2 and a non-C/C recipient IL-28B genotype were independent risk factors for cholestatic recurrent HCV. No predictive factors could be found for the occurrence of recurrent liver cirrhosis 5 and 10 years after LT. Our study shows that the HCV RNA level at week 2 and the recipient IL-28B genotype are independent, statistically significant risk factors for post-LT cholestatic HCV, and it emphasizes the importance of viral load monitoring and IL-28B genotyping for identifying HCV recipients at risk for severe HCV recurrence.

Impact of HCV genetic differences on pathobiology of disease

Multiple HCV genotypes have been isolated worldwide. Genotype seems to be involved in the main pathological aspects of HCV infection. Insulin resistance, steatosis and progression toward cirrhosis, fibrosis and hepatocellular carcinoma establish and develop following genotype-specific mechanisms. Moreover genotype influences pharmacological treatment in term of dose and duration. Pathways involved in cell proliferation, apoptosis, lipid metabolism, insulin and interferon signaling are impaired to a different extent among genotypes, leading to distinct pathological settings. Genotype 1 is associated with a more aggressive disease with increased insulin resistance, worst response to therapy, higher risk of cirrhosis and hepatocellular carcinoma development, while genotype 3 is associated with increased steatosis and fibrosis. The identification and characterization of HCV types and subtypes provides insight into the different outcome of HCV infection and responsiveness to therapy. In the present article, we focused on the pathogenicity of HCV genotypes and their effect on disease progression and treatment.

Human cell types important for hepatitis C virus replication in vivo and in vitro: old assertions and current evidence

Hepatitis C Virus (HCV) is a single stranded RNA virus which produces negative strand RNA as a replicative intermediate. We analyzed 75 RT-PCR studies that tested for negative strand HCV RNA in liver and other human tissues. 85% of the studies that investigated extrahepatic replication of HCV found one or more samples positive for replicative RNA. Studies using in situ hybridization, immunofluorescence, immunohistochemistry, and quasispecies analysis also demonstrated the presence of replicating HCV in various extrahepatic human tissues, and provide evidence that HCV replicates in macrophages, B cells, T cells, and other extrahepatic tissues. We also analyzed both short term and long term in vitro systems used to culture HCV. These systems vary in their purposes and methods, but long term culturing of HCV in B cells, T cells, and other cell types has been used to analyze replication. It is therefore now possible to study HIV-HCV co-infections and HCV replication in vitro.

Clinicopathological features of hepatitis C virus disease after living donor liver transplantation: relationship with in situ hybridisation data

AIMS

Recurrent hepatitis is a significant complication after liver transplantation for hepatitis C virus (HCV) disease. To evaluate responsiveness to treatment of HCV disease after liver transplantation, in situ hybridisation (ISH) was employed.

METHODS

Sense and anti-sense probes for HCV were synthesised, and ISH studies were performed on 19 liver biopsy specimens from 19 recipients who had undergone living donor liver transplantation for HCV disease. ISH positive cells and total hepatocytes were counted, and the percentage of positive cells was calculated. Other clinical findings were compared retrospectively with the ISH results.

RESULTS

The subjects were divided into three groups: recurrent HCV hepatitis (RHC, n = 11), acute cellular rejection (ACR, n = 5), and recurrent HCV hepatitis with ACR (MIX, n = 3). The percentage of ISH positive cells was almost the same degree (10-20%) in the three groups. The RHC group was subdivided into two sets of patients in whom serum HCV titres decreased (group D, n = 7) or did not decrease (group ND, n = 3) after 1 month of IFN therapy. The percentage of ISH positive cells in group D was significantly lower than that in group ND (p < 0.05)

CONCLUSIONS

ISH for the recipients with HCV may be useful for predicting the response to interferon therapy.

Association of IL28B gene variations with mathematical modeling of viral kinetics in chronic hepatitis C patients with IFN plus ribavirin therapy

Asian patients with chronic hepatitis C (CHC) are known to have better virological responses to pegylated (Peg) IFN-based therapy than Western patients. Although IL28B gene polymorphisms may contribute to this difference, whether favorable hepatitis C virus (HCV) kinetics during treatment plays a role remains unclear. We enrolled 145 consecutive Taiwanese patients with CHC receiving Peg-IFN α-2a plus ribavirin for the study. Blood samples were taken more frequently at defined intervals in the first 3 d. Peg-IFN was administered at week 1. It was then administered weekly in combination with daily ribavirin for 24 or 48 wk. A mathematical model fitted to the observed HCV kinetics was constructed, which could interpret the transient HCV titer elevation after Peg-IFN treatment. The results demonstrated a comparable viral clearance rate (c = 3.45 ± 3.73) (day(-1), mean ± SD) but lower daily viral production rate (P = 10(6)-10(12)) in our patients than those reported previously in Western patients. Of 110 patients with a sustained virological response (SVR), 47 (43%) had a transient elevation of viral titer within 12 h (proportion of 12 h/3 d: 44% in non-SVR vs. 70% in SVR; P = 0.029). Among 91 patients with available rs8099917 data, patients with the TT genotype had an early surge of viral titer after therapy and a higher SVR and viral clearance rate than those with the GT genotype. In conclusion, Taiwanese patients with CHC receiving Peg-IFN plus ribavirin therapy have a lower daily viral production rate than Western patients, and the rs8099917 TT genotype may contribute to the increased viral clearance rate and better virological responses in these patients.

Investigation of PEG-PLGA-PEG nanoparticles-based multipolyplexes for IL-18 gene delivery

Nanoparticles were formulated with biodegradable monomethoxy (poly ethylene glycol)-poly(lactide-co-glycolide)-monomethoxy (poly ethylene glycol) of three different proportional (PEG-PLGA-PEG, lactic acid: glycolic acid = 80/20, 70/30, 50/50) and the cytotoxicity of nanoparticle was characterized according to US Pharmacopoeia XXIII recommendations on various cell lines, including L929, Chang's hepatocytes, primary mouse myoblasts, osteoblasts, and renal vascular endothelial cells. mIL-18 gene was first condensed by polycationic peptide polylysine (PLL), and then encapsulated in the PEG-PLGA-PEG NPs as a novel multi-polyplex gene delivery system - Polymer-PLL-DNA. (PPDs) After lyopholization, the morphology, particle size, zeta potential, and the integrity of DNA in the NPs were investigated. The expression of mIL-18 gene on CT-26 cells in vitro were determined by western blot, while in vivo efficacy was evaluated by tumor inhibition rate, histological section, and survival curve in pulmonary metastasis of colon cancer in BALB/c mice model. Results showed that the cytotoxicity of blank nanoparticles was related to the degradation properties of the polymers with different compositions. The NPs with LA:GA = 70/30 (NPs-73) was optimal for intravenous injection due to its low cytotoxicity. Physicochemical properties of the PPDs were not changed during the lyopholization, while mIL-18 was successfully expressed in vitro. The anti-tumor efficacy in vivo of PPDs showed improvement especially combined with chemotherapy of cisplatin, and confirmed the promising application of the PPDs system, which compared with any single treatment.

Hepatitis C virus recurrence after liver transplantation: biomarkers of disease and fibrosis progression

End-stage liver disease due to hepatitis C virus infection (HCV) is the principal indication for liver transplantation. In the USA, over a third of available liver allografts are transplanted into recipients with chronic HCV infection. Reinfection of the graft is universal, but the impact of reinfection on short- and long-term liver function is highly variable. HCV infection in liver transplantation recipients is characterized by an accelerated fibrogenesis, with approximately a third of patients developing cirrhosis within 5 years of follow-up. HCV is associated with decreased patient and graft survival when compared with other indications of orthotopic liver transplantation. The mechanisms responsible for the accelerated liver damage in HCV-infected orthotopic liver transplantation recipients remain largely unknown.

Human liver transplantation as a model to study hepatitis C virus pathogenesis

Hepatitis C is a leading etiology of liver cancer and a leading reason for liver transplantation. Although new therapies have improved the rates of sustained response, a large proportion of patients (approximately 50%) fail to respond to antiviral treatment, thus remaining at risk for disease progression. Although chimpanzees have been used to study hepatitis C virus biology and treatments, their cost is quite high, and their use is strictly regulated; indeed, the National Institutes of Health no longer supports the breeding of chimpanzees for study. The development of hepatitis C virus therapies has been hindered by the relative paucity of small animal models for studying hepatitis C virus pathogenesis. This review presents the strengths of human liver transplantation and highlights the advances derived from this model, including insights into viral kinetics and quasispecies, viral receptor binding and entry, and innate and adaptive immunity. Moreover, consideration is given to current and emerging antiviral therapeutic approaches based on translational research results.

Progress towards improving antiviral therapy for hepatitis C with hepatitis C virus polymerase inhibitors. Part I: Nucleoside analogues

BACKGROUND

With an increasing worldwide burden of liver failure and liver cancer from chronic hepatitis C virus (HCV) infection, discovery and development efforts for new antiviral medicines for HCV are expanding rapidly. Two HCV protease inhibitors (PIs), telaprevir (VX950) and boceprevir (SCH503034), are now furthest along in clinical development, with Phase II data suggesting a potential treatment advance with triple combination regimens comprising a protease inhibitor, pegylated interferon and ribavirin. However, the current data suggest that such regimens will fail to produce sustained virologic responses in > or = 30 - 40% of patients, and tolerance of interferon/ribavirin treatment regimens is often problematic; hence, there is a need for continued development of new anti-HCV agents to further optimize treatment efficacy and safety. The HCV polymerase (HCV Pol) is an attractive target for antiviral therapy because the gene sequences encoding HCV Pol are relatively conserved across the six main HCV genotypes and the emergence of viral resistance is expected to be relatively slow for pharmaceutical agents, such as nucleoside analogues, that are targeted to the active (catalytic) site of HCV Pol.

METHODS

This review (Part I) of HCV Pol inhibitors focuses on the scientific rationale and recent development progress for nucleoside-type HCV Pol inhibitors; a subsequent review (Part II) will assess progress with non-nucleosidic HCV Pol inhibitors.

RESULTS/CONCLUSIONS

Early clinical data for several nucleosides targeted to HCV Pol indicate marked antiviral effects and a likelihood of relatively slow HCV resistance, consistent with the profile of nucleosidic inhibitors of HIV and hepatitis B virus infection and supporting potentially important roles for nucleoside agents in optimizing combination therapies for HCV infection. Optimally effective future anti-HCV therapies are likely to be based on multi-class treatment regimens combining polymerase and PIs, together with pegylated interferon and ribavirin or pharmaceutical agents from other mechanistic classes.

Detection of neutralizing antibodies with HCV pseudoparticles (HCVpp)

Infectious HCV pseudoparticles (HCVpp) can be assembled by display of unmodified and functional HCV glycoproteins on retroviral and lentiviral core particles. HCVpp have been shown to mimic the early infection steps of parental HCV. The presence of a marker gene packaged within these HCV pseudoparticles allows reliable and fast determination of infectivity mediated by the HCV glycoproteins. With this highly flexible system, E1E2 from a broad range of HCV strains can be investigated, including autologous HCV strains from patients' virus, and it has allowed careful investigation of the humoral response to HCV.

The natural history of recurrent hepatitis C and what influences this

1. Liver failure and liver cancer from chronic hepatitis C are the most common indications for liver transplantation and numbers of both are projected to double over the next 20 years. 2. Recurrent hepatitis C infection of the allograft is universal and immediate following liver transplantation and associated with accelerated progression to cirrhosis, graft loss and death. 3. Graft and patient survival is reduced in liver transplant recipients with recurrent HCV infection compared to HCV-negative recipients. 4. The natural history of chronic hepatitis C is accelerated following liver transplantation compared C, with 20% progressing to cirrhosis by 5 years. However, the rate of fibrosis progression is not uniform and may increase over time. 5. The rates of progression from cirrhosis to decompensation and from decompensation to death are also accelerated following liver transplantation. 6. Multiple host, donor and viral factors are associated with rapid fibrosis progression and HCV-related graft failure. 7. Over the last decade, graft and patient survival rates have improved following liver transplantation for non-HCV disease but not for HCV-cirrhosis. This may reflect worsening donor quality and changes in immunosuppression strategies over recent years. 8. Viral eradication by antiviral therapy prevents disease progression and improves survival. 9. The severity of recurrent hepatitis C at one year post-transplant predicts subsequent progression to cirrhosis. Annual protocol biopsies are recommended to help determine need for antiviral therapy. 10. The projected impact of recurrent hepatitis C on graft and patient survival can only be avoided by the development of safe and effective antiviral strategies which can both prevent initial graft infection and eradicate established hepatitis C recurrence.

Impact of steroids on hepatitis C virus replication in vivo and in vitro

Chronic hepatitis C virus (HCV) infection is the leading indication for liver transplantation. Transplantation outcome is often compromised by a rapid re-infection of the graft. Several factors have been implicated in the increased severity of recurrence, including steroid-based immunosuppression. Evidence suggests that steroid boluses used to treat acute rejection are associated with an increase in HCV viral load and the severity of recurrence. Two possible mechanisms for a steroid-mediated effect on HCV viral loads can be postulated, the first being a direct effect of steroids on the virus by enhancing its replication. The second, an indirect effect due to the suppression of the HCV immune response, allows unrestricted HCV replication. To investigate the direct effect of steroids on HCV replication, dexamethasone (Dex) and prednisolone (Pred) were tested in an in vitro replicon model. HCV replication was assessed on the basis of luciferase reporter expression (luminescence) and HCV RNA (RT-PCR). At clinically relevant concentrations (1-10 nM), treatment with both Dex and Pred did not enhance, but resulted in a slight reduction of relative luciferase activity (HCV replication), which was independent of increased cellular protein content and reduced cell proliferation. This minor reduction of HCV replication was confirmed by RT-PCR showing more than 41% reduction in HCV RNA levels. In conclusion, despite clinical evidence that the use of steroids aggravates recurrence of HCV, our in vitro study suggests that there is no direct stimulatory effect of steroids on the replication of HCV. As such, the increased viral loads after high-dose steroid treatment are more likely due to a downregulation of the immune response. In such patients, a dampened immune response allows viruses like HCV to replicate free of immune-mediated killing of their host cells. When a change occurs, such as a tapering or an alteration of immunosuppressant drugs, the immune system reinitiates and vigorously attempts to control the virus, resulting in acceleration of liver damage. Therefore, either steroid avoidance or maintaining low levels, coupled with a slow tapering of corticosteroids, may be beneficial to HCV-infected transplantation recipients.

[Treatment of recurrent hepatitis C virus infection after liver transplantation]

The main indication of liver transplantation is the final stage of liver cirrhosis developed in hepatitis C virus (HCV) infection. The recurrence of HCV infection after transplantation is a common situation. The recurrent hepatitis C is a progressive disease, in 20 percent of patients it produces liver cirrhosis without treatment beside immunosuppression within 5 years. The treatment of recurrent HCV infection is the most important factor of the survival in patients with transplantation. The authors review the factors influencing the progression of recurrent HCV infection on the basis of literary data and also on their observation. They discuss in details the effect of immunosuppressive treatment, the importance in the selection of corresponding immunosuppressive drugs. They review the main keypoints in the diagnosis of recurrent hepatitis C, underline the important role of liver biopsy carried out according to the protocol in the diagnosis, furthermore the hard consultation among pathologist, hepatologist and surgeon. They demonstrate the observations with the treatment of patients on the waiting list, the results in the early, preemptive treatment of recurrent chronic hepatitis, furthermore the treatment modalities and the results in patients with chronic hepatitis C histologically proved. The drug of choice of chronic hepatitis C after transplantation is the combined therapy with pegylated interferon and ribavirin. This therapy is able to assure virus-free stage in 20-50 percent of patients. In the virus-free patients the inflammatory activity in the liver significantly decreases, the histologic activity index improves. There are data showing the effect of treatment for inhibiting the fibrosis, but multicenter studies are necessary for the confirmation of these data. The advantage of early antiviral therapy without histologic alteration has not been confirmed by most of the trials. The anaemia and the neutropenia are frequent side effects in this patient group, that is why the applications of erythropoietin and granulocyte stimulating factor are recommended. Further trials and clinical studies are necessary for the optimal treatment of patients with recurrent hepatitis C, and to determine the dosage of pegylated interferon and ribavirin, to decrease the duration of therapy and the side effects, finally to achieve a healing phase of higher degree.

Chronic ductopenic rejection in patients with recurrent hepatitis C virus treated with pegylated interferon alfa-2a and ribavirin

BACKGROUND

Interferon use for post liver transplantation (LT) recurrent hepatitis C (HCV) has not consistently been associated with acute cellular rejection (ACR). We examined the incidence of chronic ductopenic rejection (CR) in patients receiving pegylated interferon alfa-2a and ribavirin (PEG) to treat recurrent HCV.

METHODS

A chart review of 12 patients developing CR while receiving an escalating dose regimen of PEG with protocol liver biopsies every 6 months was conducted. Values are shown as median (range).

RESULTS

Twelve of the 70 patients treated with PEG developed CR. Median age at LT was 53 (37-63) years; immunosuppression consisted of tacrolimus or cyclosporine with prednisone. PEG was started at 3.6 (0.2-13.5) years after LT. Two patients had one episode of ACR before PEG. Four patients had first ACR while receiving PEG. CR was diagnosed after 12 (4-17) months of PEG; by then 8 patients had undetectable HCV-RNA. Tacrolimus and cyclosporine levels (ng/mL) were 7.9 (3.2-18.9) and 76 (71-93) before PEG, and 6.9 (3.7-9.7) and 130 (81-153) at CR. Six patients were treated more than 1 year with PEG; three had undetectable HCV-RNA when CR was diagnosed. Five patients are being treated for CR; one has been listed for LT; two patients were retransplanted. Five patients died as a result of sepsis partially related to CR.

CONCLUSIONS

Treatment with pegylated-interferon alpha-2a and ribavirin may trigger rapidly progressive CR in patients with therapeutic immunosuppressive trough levels, with or without first inducing ACR.

Review article: the treatment of hepatitis C virus recurrence after liver transplantation

BACKGROUND

Recurrent hepatitis C represents a major challenge for the liver transplant community. Given the potentially significant impact that hepatitis C recurrence has on graft and patient survival, several treatment strategies have been utilized to prevent/slow the progression to hepatitis C-related graft failure.

AIM

To review the efficacy and applicability of treatment strategies for managing recurrent hepatitis C.

METHODS

Search of MEDLINE (1990 to December 2006) and national meeting abstracts. Search terms included hepatitis C, liver transplantation, treatment, sustained virological response (SVR), and end of treatment virological response. An emphasis was placed on randomized trials.

RESULTS

The largest study of treatment prior to liver transplantation (n = 124) achieved SVR in 24%. Eight randomized trials (n = 383) examined the efficacy of preemptive therapy with SVR ranging from 0-33%. Eligibility for treatment was low and dose reduction common. Four randomized trials (n = 245; all abstracts) have reported SVR from 33-42% for treating those with histological evidence of recurrent disease.

CONCLUSIONS

Therapies for treating hepatitis C recurrence have limited applicability and tolerability, and they have a low SVR. Based on available results, preemptive therapy is not recommended. Pegylated interferon and ribavirin is currently the preferred choice for treating established recurrence. There is an urgent need for safer and more effective anti-viral therapy in this situation.

Viral dynamics in transplant patients: implications for disease

Viral infections cause substantial morbidity and mortality in transplant patients. Quantifying viral loads is widely appreciated as a direct means to diagnose and monitor the course of viral infections. Recent studies indicate that the kinetics of viral load changes rather than single viral load measurements better correlate with organ involvement. In this Review, we will summarise the current knowledge regarding the kinetics of viruses relevant to transplantation including cytomegalovirus, Epstein-Barr virus, the herpes viruses 6 and 7, hepatitis C virus, GB virus C, adenovirus, and the emerging human polyomavirus type BK. We discuss the implications of viral kinetics for organ pathology as well as for the evaluation of antiviral interventions in transplant patients.

Management of hepatitis C infection after liver transplantation

Recurrent hepatitis C virus (HCV) infection after orthotopic liver transplantation (OLT) has been associated with progression to cirrhosis in approximately 20% of patients, 5 years postoperatively. Accelerated decompensation has also been noted when compared with cirrhosis in non-transplant patients. Different treatment strategies are available for recurrent HCV infection post-OLT, but efforts are hindered by the modest response rates, poor tolerability and the risk of rejection as well as graft loss. Anti-HCV immunoglobulin therapy to prevent graft infection with HCV has no established role at present but studies are ongoing. Treatment prior to transplantation in patients with decompensated cirrhosis has been evaluated but the results are too preliminary to make firm recommendations. Prophylactic interferon-based antiviral therapy in the early postoperative period to prevent graft infection was shown to have low response rates and high rates of adverse effects. Treatment of established recurrent HCV infection with combination peginterferon (pegylated interferon) and ribavirin is associated with 10-59% sustained virological response and the predictive value of a positive early virological response has been validated in the post-transplant setting. Improvement in inflammatory activity after viral eradication is well established, but fibrosis regression or stabilisation is less predictable and factors such as rejection and biliary complications may still contribute to graft loss. Most studies have initiated therapy at least 6 months postoperatively in order to optimise patient tolerance and enable the addition of ribavirin. The use of adjuvant agents to treat drug-induced neutropenia and anaemia in this population is evolving and becoming a crucial part of therapy. Determination of optimal doses of both pegylated interferon and ribavirin, and guidance on when to stop treatment, as well as improving tolerability are important steps in achieving higher response rates and minimising drug toxicity.

Detection of HCV antigens in liver graft: relevance to the management of recurrent post-liver transplant hepatitis C

The aim of this study was to evaluate how the immunohistochemical detection of liver hepatitis C virus (HCV) antigens (HCV-Ag) could support the histologic diagnosis and influence the clinical management of post-liver transplantation (LT) liver disease. A total of 215 liver specimens from 152 HCV-positive patients with post-LT liver disease were studied. Histologic coding was: hepatitis (126), rejection (34), undefined (24; coexisting rejection grade I and hepatitis), or other (31). The percentage of HCV-Ag infected hepatocytes were evaluated, on frozen sections, by an immunoperoxidase technique. HCV-Ag were detectable early in 57% of cases within 30 days post-LT, 92% of cases between 31 and 180 days, and 74% of cases after more than 180 days. Overall, HCV-Ag were detected more frequently in histologic hepatitis as compared to rejection (P < 0.0001) with a higher percentage of positive hepatocytes (P < 0.00001). In 16 patients with a high number of HCV-Ag-positive hepatocytes (65%; range 40-90%) a clinical diagnosis of recurrent hepatitis (RHC) was made despite inconclusive histopathologic diagnosis. Multivariate analysis identified the percentage of HCV-Ag-positive hepatocytes and the time post-LT as independent predictors for RHC (P = 0.008 and P = 0.041, respectively) and the number of HCV-Ag-positive hepatocytes >/=50% as the only independent predictor for nonresponse (P < 0.001) in 26 patients treated with alpha-interferon plus ribavirin. In conclusion, HCV reinfection occurs early post-LT, reaching its peak within 6 months. Immunohistochemical detection of post-LT HCV reinfection support the diagnosis of hepatitis when the histologic features are not conclusive. A high number of infected cells, independently from the genotype, represents a negative predictive factor of response to antiviral treatment.

HBV and HCV infections and acute rejection differentially modulate CD95 and CD28 expression on peripheral blood lymphocytes after liver transplantation

Hepatitis B virus (HBV) and hepatitis C virus (HCV) generally reinfect liver graft early posttransplantation and lead to poorer graft and patient survivals. In the present study the influence of acute rejection (AR), HBV and HCV infections, and human leukocyte antigen (HLA) class-I compatibility on the expression of CD28 (in 237 liver recipients) and CD95 (in 114 liver recipients) on peripheral blood cells were evaluated by flow cytometry during the first month after transplantation. HBV/HCV infections induced strong CD95 upregulation on CD3+ lymphocytes. Maximal CD95 upmodulation was found in infected recipients showing partial HLA class-I compatibility. AR and virus reinfection could be distinguished because CD28 was upregulated on CD4+ lymphocytes only in recipients with AR, irrespective of their status regarding HBV/HCV infections. In conclusion, cytometric co-evaluation of CD95 and CD28 expression on peripheral blood lymphocytes could be useful to discriminate AR from cellular activation induced by viral reinfection of the liver graft.

Impact of Double-Filtration Plasmapheresis in Combination with Interferon and Ribavirin in Living Donor Liver Transplant Recipients with Hepatitis C

Double-filtration plasmapheresis (DFPP) selectively removes high molecular weight substances including hepatitis C virus (HCV). Four live donor liver transplantation (LDLT) recipients with HCV received combination therapy with low-dose interferon (IFN) and ribavirin with DFPP. Three patients underwent this therapy for prophylaxis of HCV recurrence, and one for treating fibrosing cholestatic hepatitis (FCH). The combination therapy and DFPP decreased HCV RNA levels to 8.2% +/- 2.9% and 0.7% +/- 0.5% by the 5th and 30th day of treatment, respectively. Three patients who underwent DFPP for prophylaxis showed no evidence of HCV recurrence for >1 year after treatment. The patient whose graft showed FCH, recovered dramatically after the DFPP treatment. DFPP appeared to be effective in reducing HCV viremia and preventing HCV recurrence in patients with high HCV RNA levels after LDLT. Moreover, it may become a rescue therapy for FCH in a liver transplant recipient with hepatitis C.

Management of Recurrent Hepatitis C in Liver Transplant Recipients

Recurrent HCV infection is universal in liver transplant recipients who are viremic pretransplant. The rate of histologic disease progression after transplantation is more rapid, and the risk of cirrhosis by 5 to 10 years is about 30%. Several donor, recipient, and viral factors have been associated with worse post-transplant outcomes in recipients with recurrent hepatitis C. Whether or not HCV-infected recipients of live donor grafts have worse out-comes compared with deceased donor graft recipients is controversial. To maximize the long-term survival of recipients with HCV infection, eradication of infection is the ultimate goal. Treatment of recurrent HCV after liver transplantation can be undertaken at several different time points: (1) prophylactically, at the time of transplantation; (2) pre-emptively, in the early post-transplant period; and (3) after established recurrent histologic disease is present. Prophylactic therapy for HCV infection has no established role at present, but studies are ongoing. Preemptive therapy using IFN and RBV has resulted in variable SVR rates (9%-43%) and is generally poorly tolerated, especially if the patient has advanced liver disease pretransplantation. Treatment of established recurrent HCV disease with combination PEGIFN and RBV is associated with a SVR in about 30% to 35% of patients overall but is limited by high rates of dose reduction or drug discontinuation. In conclusion, successful HCV eradication in the post-transplant setting is difficult with current treatment options, but it is possible. Determination of the optimal doses of antiviral drugs in transplant patients and improvements in drug tolerability may be important first steps in achieving enhanced response rates. There is a need for new drugs in this population that have greater efficacy and a better safety profile.

Kinetics of hepatitis C virus reinfection after liver transplantation

Improved understanding of hepatitis C virus (HCV) dynamics during and after liver transplantation can be useful in optimizing antiviral therapy in transplant recipients. We analyzed serum HCV ribonucleic acid (RNA) levels during and after cadaveric liver transplantation in 6 HCV patients. After removal of the liver and before the new liver started producing virions, HCV RNA levels dropped with an average half-life (t(1/2)) of 0.8 hours. Viral loads then continued to drop up to 23 hours postimplantation (t(1/2) = 3.4 hours), and began to rise (doubling-time = 2.0 days) as soon as 15 hours after the anhepatic phase. In 3 patients the viral load reached a plateau before rising, suggesting that a nonhepatic source supplied virions and balanced their intrinsic clearance. However, from the decline in viral load over the first 24 hours of the postanhepatic phase, we estimate that nonhepatic sources can at most correspond to 4% of total viral production, 96% of which occurs in the liver, even after we corrected for fluid exchanges during surgery. As the new liver was reinfected, production increased and viral load rose to a new steady state. Using nonlinear regression, we were able to fit the patients' HCV RNA data to a viral dynamic model and estimate the de novo infection rate (mean 1.5 x 10(-6) mL/virion/day), as well as the average percentage of hepatocytes infected at the posttransplantation steady state (19%). In conclusion, we have quantified liver reinfection dynamics in the absence of posttransplantation antiviral therapy. Our findings support the notion that early antiviral therapy may delay or prevent reinfection.

Monoclonal antibody AP33 defines a broadly neutralizing epitope on the hepatitis C virus E2 envelope glycoprotein

Hepatitis C virus (HCV) remains a significant threat to the general health of the world's population, and there is a pressing need for the development of new treatments and preventative vaccines. Here, we describe the generation of retrovirus-based pseudoparticles (HCVpp) incorporating a panel of full-length E1E2 clones representative of the major genotypes 1 through 6, and their application to assess the reactivity and neutralizing capability of antisera and monoclonal antibodies raised against portions of the HCV E2 envelope protein. Rabbit antisera raised against either the first hypervariable region or ectodomain of E2 showed limited and strain specific neutralization. By contrast, the monoclonal antibody (MAb) AP33 demonstrated potent neutralization of infectivity against HCVpp carrying E1E2 representative of all genotypes tested. The concentration of AP33 required to achieve 50% inhibition of infection by HCVpp of diverse genotypes ranged from 0.6 to 32 mug/ml. The epitope recognized by MAb AP33 is linear and highly conserved across different genotypes of HCV. Thus, identification of a broadly neutralizing antibody that recognizes a linear epitope is likely to be of significant benefit to future vaccine and therapeutic antibody development.

Treatment of recurrent hepatitis C after liver transplantation

Chronic hepatitis C virus (HCV) infection is the most common indication for liver transplantation in the United States and Europe, and more than 20,000 patients worldwide have undergone transplantation for complications of chronic hepatitis C. In North America, HCV accounts for 15% to 50% of the liver transplants performed in United States transplant programs. To maximize the long-term survival of liver transplant recipients who have HCV infection, eradication of infection is the ultimate goal. Pretransplant antiviral therapy with the goal of achieving viral eradication before transplantation is a consideration in some patients, especially those who have mildly decompensated liver disease. This article focuses on the management of liver transplant recipients who have HCV infection at the time of transplantation. Prophylactic and preemptive therapies, as well as treatment of established recurrent disease, are the strategies reviewed.

Evolutionary dynamics of hepatitis C virus envelope genes during chronic infection

Hepatitis C virus (HCV) envelope glycoproteins E1 and E2 are important targets for the host immune response. The genes encoding these proteins exhibit a high degree of variability that gives rise to differing phenotypic traits, including alterations in receptor-binding affinity and immune recognition and escape. In order to elucidate patterns of adaptive evolution during chronic infection, a panel of full-length E1E2 clones was generated from sequential serum samples obtained from four chronically infected individuals. By using likelihood-based methods for phylogenetic inference, the evolutionary dynamics of circulating HCV quasispecies populations were assessed and a site-by-site analysis of the d(N)/d(S) ratio was performed, to identify specific codons undergoing diversifying positive selection. HCV phylogenies, coupled with the number and distribution of selected sites, differed markedly between patients, highlighting that HCV evolution during chronic infection is a patient-specific phenomenon. This analysis shows that purifying selection is the major force acting on HCV populations in chronic infection. Whilst no significant evidence for positive selection was observed in E1, a number of sites under positive selection were identified within the ectodomain of the E2 protein. All of these sites were located in regions hypothesized to be exposed to the selective environment of the host, including a number of functionally defined domains that have been reported to be involved in immune evasion and receptor binding. Dated-tip methods for estimation of underlying HCV mutation rates were also applied to the data, enabling prediction of the most recent common ancestor for each patient's quasispecies.