Kinetics of hepatitis C virus reinfection after liver transplantation

Risk factors for hepatitis C recurrence after liver transplantation

Hepatitis C virus (HCV)-related end-stage liver disease is the main indication for liver transplantation performed in Europe and the United States. Recurrence of hepatitis C in the graft is universal and may lead to chronic hepatitis in most patients and to cirrhosis in 20-30% of patients within 5-10 years of transplantation. The natural history of HCV recurrence is highly variable but leads to a lower survival rate than other recurrent liver diseases. The immunosuppressed status and several other factors have been linked with the pattern and severity of recurrence. What remains controversial are those factors associated with fibrosis progression and how these could be modified to improve outcome of recurrent hepatitis C. No single factor but a combination of several factors is associated with fibrosis progression on the graft. The major factors associated with accelerated disease recurrence include: high viral load pre- (>10(6) IU / mL) and / or early post-transplantation (>10(7) IU / mL at 4 months), donor older than 40-50 years, prolonged ischaemic time, cytomegalovirus coinfection, over immunosuppression and / or abrupt changes in immunosuppression, HIV coinfection, infection by genotype 1b. Cautious follow-up of the pathology of the graft is mandatory including routine biopsies and / or noninvasive monitoring of fibrosis.

Clearance of hepatitis C virus after living-donor liver transplantation in spite of residual viremia on end date of interferon therapy before transplantation

Interferon (IFN) therapy is the only treatment strategy for hepatitis C virus (HCV) infection after liver transplantation (LT), but prophylactic and treatable IFN therapy after LT has been shown to be insufficient due to the adverse effects of IFN and rivabirin. In this paper, we describe the disappearance of HCV after LT without IFN therapy in the presence of residual viremia on the day of LT. We herein report our findings since this is considered an important case for the anti-HCV strategy of post LT. A 60-year old woman with LC and HCC was referred to Nagasaki University Hospital in August 2004. After she underwent LT on February 18, 2005, we injected peg-IFN-α-2a the 11th time at 18 wk and HCV-RNA was still positive in the serum at LT. The serum HCV-RNA was negative one month after operation and subsequently dissolved 15 mo after operation without IFN therapy. As a result, we speculate that if HCV-RNA is positive while HCV core antigen is negative before LT, then it may lead to clearance of HCV after LT. Therefore long acting peg-IFN-α-2a is thus considered a potentially effective agent for the treatment of HCV-related cirrhosis before LT.

Modeling hepatitis C virus dynamics: liver regeneration and critical drug efficacy

Mathematical models for hepatitis C viral (HCV) RNA kinetics have provided a means of evaluating the antiviral effectiveness of therapy, of estimating parameters such as the rate of HCV RNA clearance, and they have suggested mechanism of action against HCV for both interferon and ribavirin. Nevertheless, the model that was originally formulated by Neumann et al. [1998. Hepatitis C viral dynamics in vivo and the antiviral efficacy of interferon-alpha therapy. Science 282 (5386), 103-107] is unable to explain all of the observed HCV RNA profiles under treatment e.g., a triphasic viral decay and a viral rebound to baseline values after the cessation of therapy. Further, the half-life of productively HCV-infected cells, estimated from the second phase HCV RNA decline slope, is very variable and sometimes zero with no clear understanding of why. We show that extending the original model by including hepatocyte proliferation yields a more realistic model without any of these deficiencies. Further, we define and characterize a critical drug efficacy, such that for efficacies above the critical value HCV is ultimately cleared, while for efficacies below it, a new chronically infected viral steady-state level is reached.

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.

Viral load 1 week after liver transplantation, donor age and rejections correlate with the outcome of recurrent hepatitis C

BACKGROUND

Early identification of patients at a higher risk of rapidly progressive recurrent hepatitis post liver transplantation (LT) could help to tailor antiviral therapy.

METHODS

We studied the correlation between early post-LT viral load and the histological and clinical outcomes of 49 consecutive patients (34 males, median age 55 years) in whom viraemia was monitored at days 0, 1, 7, 30, 180 and 365 after LT.

RESULTS

Hepatitis C recurred at histology in 38 of 42 (90.5%) patients. Early viral load after LT was higher in patients with rapidly progressive hepatitis C recurrence (day 7 median HCV-RNA levels: 5.84 vs 4.93 Log(10) IU/ml, P=0.003). Day 7 HCV-RNA levels >/=2.5 x 10(5) IU/ml, donor age >60 years and rejection episodes were independently associated with progression to cirrhosis within one year post-LT [P=0.018, odds ratio (OR) 27.59; P=0.043, OR 13.85 and P=0.048, OR 9.95, respectively]. Day 7 viraemia and rejection episodes were independently associated with 5-years survival. Day 7 viraemia, in combination with acute hepatitis and/or donor age, showed 80% sensitivity, 94% specificity and 90.5% diagnostic accuracy to identify severe recurrence.

CONCLUSIONS

Early post-LT HCV-RNA correlates with the severity of hepatitis C recurrence and in combination with donor age (>60 years) and rejections, identifies patients with a high risk of severe recurrence and candidates of cost-effective pre-emptive antiviral therapy.

Mathematical modeling of subgenomic hepatitis C virus replication in Huh-7 cells

Cell-based hepatitis C virus (HCV) replicon systems have provided a means for understanding HCV replication mechanisms and for testing new antiviral agents. We describe here a mathematical model of HCV replication that assumes that the translation of the HCV polyprotein occurs in the cytoplasm, that HCV RNA synthesis occurs in vesicular-membrane structures, and that the strategy of replication involves a double-stranded RNA intermediate. Our results shed light on the intracellular dynamics of subgenomic HCV RNA replication from transfection to steady state within Huh-7 cells. We predict the following: (i) about 6 x 10(3) ribosomes are involved in generating millions of HCV NS5B-polymerase molecules in a Huh-7 cell, (ii) the observed 10:1 asymmetry of plus- to minus-strand RNA levels can be explained by a higher-affinity (200-fold) interaction of HCV NS5B polymerase-containing replication complexes with HCV minus-strand RNA over HCV plus-strand RNA in order to initiate synthesis, (iii) the latter higher affinity can also account for the observed approximately 6:1 plus-strand/minus-strand ratio in vesicular-membrane structures, and (iv) the introduction of higher numbers of HCV plus-strand RNA by transfection leads to faster attainment of steady-state but does not change the steady-state HCV RNA level. Fully permissive HCV replication systems have been developed, and the model presented here is a first step toward building a comprehensive model for complete HCV replication. Moreover, the model can serve as an important tool in understanding HCV replication mechanisms and should prove useful in designing and evaluating new antivirals against HCV.

Monoclonal antibody HCV-AbXTL68 in patients undergoing liver transplantation for HCV: results of a phase 2 randomized study

A randomized, double-blind, dose-escalation study evaluated the safety and efficacy of hepatitis C virus (HCV)-Ab(XTL)68, a neutralizing, high-affinity, fully human, anti-E2 monoclonal antibody, in 24 HCV-positive patients undergoing liver transplantation. HCV-Ab(XTL)68 or placebo was administered at doses from 20-240 mg as 2-4 infusions during the first 24 hours after transplantation, followed by daily infusions for 6 days, weekly infusions for 3 weeks, and either 2 or 4 weekly infusions for 8 weeks. Serum concentrations of total anti-E2 obtained during daily infusions of 120-240 mg HCV-Ab(XTL)68 were 50-200 microg/mL above concentrations in the placebo group. Median serum concentration of HCV RNA dropped below baseline in all groups immediately after transplantation. On day 2, median change from baseline in HCV RNA was -1.8 and -2.4 log in the 120-mg and 240-mg groups, respectively, compared with -1.5 log with placebo. The difference was lost after day 7 when the dosing frequency was reduced. The coincidence of increases in anti-E2 with decreases in HCV RNA concentration indicate that the dose-related changes in HCV RNA concentration were a result of HCV-Ab(XTL)68 administration in the 120- and 240-mg groups. The overall incidence of nonfatal serious adverse events was higher with placebo (60%) vs. all active treatments combined (42%). In conclusion, HCV-Ab(XTL)68 may decrease serum concentrations of HCV RNA in patients after liver transplantation. Studies evaluating more frequent daily dosing at doses >120 mg are necessary to investigate sustained viral suppression in this population.