New approaches to the treatment of chronic viral hepatitis B and C

A note on the global properties of an age-structured viral dynamic model with multiple target cell populations

Some viruses can infect different classes of cells. The age of infection can affect the dynamics of infected cells and viral production. Here we develop a viral dynamic model with the age of infection and multiple target cell populations. Using the methods of semigroup and Lyapunov function, we study the global asymptotic property of the steady states of the model. The results show that when the basic reproductive number falls below 1, the infection is predicted to die out. When the basic reproductive number exceeds 1, there exists a unique infected steady state which is globally asymptotically stable. The model can be extended to study virus dynamics with multiple compartments or coinfection by multiple types of viruses. We also show that under some scenarios the age-structured model can be reduced to an ordinary differential equation system with or without time delays.

Global properties for an age-structured within-host model with Crowley–Martin functional response

Based on a multi-scale view, in this paper, we study an age-structured within-host model with Crowley–Martin functional response for the control of viral infections. By means of semigroup and Lyapunov function, the global asymptotical property of infected steady state of the model is obtained. The results show that when the basic reproductive number falls below unity, the infection dies out. However, when the basic reproductive number exceeds unity, there exists a unique positive equilibrium which is globally asymptotically stable. This model can be deduced to different viral models with or without time delay.

Propagation of HBV with spatial dependence

A mathematical model is proposed to simulate the hepatitis B virus (HBV) infection with spatial dependence. The existence of traveling waves is established via the geometric singular perturbation method. Numerical simulations show that the model admits non-monotone traveling profiles. Influences of various parameters on the minimum wave speed are also discussed.

The Prevalence, Clinical Features and Response to Antiviral Therapy of Patients with Chronic Hepatitis C who are Seropositive for Liver–Kidney Microsome Type 1 Antibodies

Background

Antibodies to liver–kidney microsome type 1 (anti-LKM-1), which are a marker of autoimmune hepatitis, are found in a minority of patients with chronic hepatitis C virus (HCV) infection. Whether interferon/ribavirin therapy is safe and effective in these patients is unclear.

Aim

To describe the prevalence, clinical features and response to interferon/ribavirin therapy of anti-LKM-1 seropositive patients with chronic hepatitis C.

Patients and methods

All anti-LKM-1 seropositive patients with chronic hepatitis C who between 1997 and 2002 underwent a diagnostic liver biopsy at the Liver Center Maggiore Hospital, Milan, were studied. Serum HCV RNA was tested by in-house PCR with a limit sensitivity of 50 IU/ml. Tissue antibodies were assessed by indirect immunofluorescence on cryostat sections from rat liver, kidney and stomach. Liver biopsies were graded and staged by the Ishak score. Autoimmune hepatitis was defined according to the International Autoimmune Hepatitis Grading (IAHG) score.

Results

Forty-eight (1.8%) of 2675 HCV patients circulated anti-LKM-1 (30 females, 55 years of age). Twenty-eight had genotype 2, 18 genotype 1, and two genotype 3. Aminotransferase levels had been high for 23 ± 12 years, on average. Using IAHG, autoimmune hepatitis was excluded in 44 patients (92%) and found to be probable in 4 patients (8%). Chronic hepatitis was histologically mild in 34 patients (70%), moderate to severe in 7 patients (15%) and with cirrhosis in 7 patients (15%). A sustained virological response (SVR) was achieved in 20 of the 27 patients who received interferon/ribavirin (13 genotype 2c with 87% SVR, and 7 genotype 1b with 58% SVR). None of the patients had serum aminotransferases, immunoglobulins or anti-LKM-1 levels flaring following therapy.

Conclusions

LKM-1 antibodies rarely occur in patients with chronic hepatitis C and do not predict autoimmune hepatitis, interferon/ribavirin hyporesponsiveness or immune-related reactions to therapy.

Optimal induction of hepatitis C virus envelope-specific immunity by bicistronic plasmid DNA inoculation with the granulocyte-macrophage colony-stimulating factor gene

In this study, we have constructed various DNA vaccine vectors that carried hepatitis C virus (HCV) envelope genes without and with the granulocyte-macrophage colony-stimulating factor (GM-CSF) gene in several different ways. In Buffalo rats that received plasmids carrying the HCV envelope genes, which encode envelope proteins E1 and E2, both antibody and lymphoproliferative responses against these proteins were induced. These responses were greatly enhanced by the codelivery of the GM-CSF gene. In particular, inoculation with a bicistronic plasmid that independently expressed the GM-CSF gene and the envelope genes in the same construct generated the highest antibody titers and significantly increased lymphoproliferative responses against these proteins. Moreover, strong antibody responses to homologous and heterologous hypervariable region 1 peptides were elicited in the immunized rats.

Robustaflavone, a potential non-nucleoside anti-hepatitis B agent

Robustaflavone, a naturally occurring biflavanoid isolated from Rhus succedanea, was found to be a potent inhibitor of hepatitis B virus (HBV) replication in 2.2.15 cells, with an effective concentration (EC50) of 0.25 microM, and a selectivity index (SI, IC50/EC90) of 153. Robustaflavone hexaacetate inhibited HBV replication with an EC50 of 0.73 microM, but exhibited no cytotoxicity at concentrations up to 1000 microM. Combinations of robustaflavone with penciclovir and lamivudine displayed synergistic anti-HBV activity, having the most pronounced effects when the combination ratios were similar to the ratio of EC50 potencies. Thus, a 1:1 combination of robustaflavone and penciclovir exhibited an EC50 of 0.11 microM and an SI of 684, while a 10:1 combination of robustaflavone and lamivudine exhibited an EC50 of 0.054 microM and an SI of 894. Statistical analyses of the combination data using the Combostat program confirmed that robustaflavone exhibited synergism with both penciclovir and lamivudine.

Hepatitis C

Hepatitis C virus (HCV) infection afflicts millions of people in the United States and worldwide. We examine the epidemiology of HCV infection, the molecular biology of the virus, the pathophysiology of infection, the clinical diagnosis and manifestations of infection, and the treatment of HCV infection.

Evaluation of Western Blot in Routine Diagnosis of Hepatitis C Virus

Hepatitis C virus (HCV) is among the major causes of parenterally transmitted hepatitis. Detection of infected persons would greatly diminish transmission rates and is therefore a significant parameter for prevention. Current assays are not able to resolve all cases and sometimes the results are controversial. The present study outlines problems that arise during routine testing. Two ELISA tests and three confirmatory tests were used and Polymerase Chain Reaction (PCR) data were available for some of the samples. The results of this study show that only 77.4% of samples positive for both ELISAs were confirmed as being positive. Controversial ELISA results remained controversial, depending on the confirmatory test used. PCR results, though not complete, point to the major problem of Western blot (WB) negative sera that prove positive for the viral genome and have to be excluded from screening for blood and organ donation. Since PCR cannot be used as a routine screening procedure, improvement of the routine assays is needed to minimize ambiguous results.

Thymosin-alpha 1, but not interferon-alpha, specifically inhibits anchorage-independent growth of hepatitis B viral transfected HepG2 cells

BACKGROUND

Thymosin-alpha 1 is a biological response modifier that has been used clinically, alone and in combination with interferon-alpha for the treatment of chronic hepatitis B viral infection. Both immunomodulatory and immediate intracellular mechanisms have been postulated to explain the effect of these two agents on HBV-infected hepatocytes.

METHODS

In this study, hepatitis B transfected HepG2 hepatoblastoma cells (HepG2-Nu2), derived from 2.2.15 cells, were used as an in vitro model to determine the efficacy of thymosin-alpha 1 and interferon-alpha, individually and combined, as proliferation inhibitors of HBV-infected cells. For comparison, parental HepG2 cells and an SV40-transfected HepG2 cell line (HepG2P9T2) were also evaluated.

RESULTS

In a clonogenic soft agar assay, thymosin-alpha 1 inhibited the anchorage-independent growth of the HepG2-Nu2 cells by 40% compared with untreated controls, but did not inhibit parental HepG2 or HepG2P9T2 clonal growth. The response was dose dependent over concentrations spanning three log units. In comparison, 10000 units/ml of interferon-alpha inhibited parental HepG2, HepG2-N4Z and HepG2P9T2 by 33%, 41% and 87%, respectively. The combination of thymosin-alpha 1 and interferon-alpha consistently inhibited HepG2-Nu2 clonal growth more effectively than either treatment alone, reaching maximum inhibition levels of 51%.

CONCLUSIONS

Thymosin-alpha 1 specifically inhibits the tumorigenic growth of HBV-transfected HepG2 cells in contrast to the general inhibition displayed by interferon-alpha. This panel of cell lines may be an important resource for dissecting the mechanism by which thymosin, alone or in combination with other drugs, influences HBV-infected hepatocytes and/or HBV-associated carcinoma.

Evaluation and treatment of chronic hepatitis C infection

Hepatic C virus (HCV) has been recognized increasingly as a major public health crisis in the United States, causing infection in an estimated 3.5 million people and resulting in 8000 to 10,000 deaths annually from liver-related complications. This article focuses on the clinical aspects and diagnosis of hepatitis C, the importance of excluding other chronic liver diseases, and the current basis and strategy for treatment of HCV infection with interferon. Ideally, it will help primary care providers with the task of evaluating, diagnosing, teaching, and caring for patients with this chronic, potentially debilitating, and lethal disease.