Economic evaluation of early monotherapy versus delayed monotherapy or combination therapy in patients with acute hepatitis C in Germany.

BACKGROUND: Antiviral treatment of acute hepatitis C virus (HCV) almost doubles the chance of sustained virological response (SVR) compared with that achievable by treating chronic HCV. AIM: To conduct a health economic evaluation comparing early and delayed therapies for acute HCV in Germany. METHODS: One hundred and thirty-three patients with acute HCV were evaluated in two early monotherapy (EMT) studies and 60 in a delayed therapy study. Efficacy was determined by SVR. In the EMT studies, patients were treated with either standard or pegylated interferon for 24 weeks. In the delayed therapy study, patients with persisting infection were treated with interferon monotherapy or combination therapy with ribavirin for a median of 36 weeks. We conducted a cost-effectiveness analysis based on the study results and a linear simulation model based on current treatment recommendations. RESULTS: The SVR rate for the sex-adjusted on-treatment analysis between early and delayed therapies was not significantly different (92.7 vs. 90.9%; P = 0.7). Medication costs accounted for more than 90% in both treatment options. Direct medical costs of early therapy (euro7064/patient) were euro321 lower than those of delayed therapy (P = 0.8). The incremental cost-effectiveness ratio was -178 euro/SVR(%) (confidence interval: -224 to 360 euro/SVR(%)). Average modeled direct medical costs of delayed combination therapy were from euro6745 to euro8299 per patient (from approximately 7% less up to 15% higher than EMT). Spontaneous viral clearance and therapy duration were the most sensitive variables. CONCLUSION: There was no significant efficacy and cost difference between therapy alternatives in base cases. However, in the majority of scenarios in the sensitivity analyses, EMT was a more cost-effective option in acute HCV therapy.

Efficacy of amantadine on quality of life in patients with chronic hepatitis C treated with interferon-alpha and ribavirin: results from a randomized, placebo-controlled, double-blind trial.

AIM: The aim of this study was to investigate whether amantadine reduces deterioration of quality of life in patients with chronic hepatitis C during and after treatment with interferon-alpha (IFN-alpha) and ribavirin. PATIENTS AND METHODS: In this randomized, prospective, placebo-controlled, multicenter trial, previously untreated patients with chronic hepatitis C were treated with IFN-alpha plus ribavirin [17] and randomized for treatment with amantadine (200 mg/day, orally, n=136) or placebo (n=131). Quality of life was assessed with the 'Profile of Mood States' scale and the 'Everyday Life' questionnaire at baseline, treatment week (TW) 8, TW24, TW48, and at follow-up. RESULTS: Early during treatment at TW8, quality of life was not different between patients in the control and the amantadine group. At TW24, the control group but not the amantadine group, however, showed significant deterioration of the modalities depression, fatigue, and vigor compared with baseline. Especially, nonresponders in the amantadine group showed significantly lower deterioration of depression, anger, mind function, everyday life, and zest for life than those in the placebo group. After treatment, the beneficial effects of amantadine disappeared. CONCLUSION: The addition of amantadine to IFN-alpha plus ribavirin combination therapy may reduce deterioration of depression, fatigue, and vigor during treatment but does not affect quality of life after treatment.

Tracking virus-specific CD4+ T cells during and after acute hepatitis C virus infection.

BACKGROUND: CD4+ T cell help is critical in maintaining antiviral immune responses and such help has been shown to be sustained in acute resolving hepatitis C. In contrast, in evolving chronic hepatitis C CD4+ T cell helper responses appear to be absent or short-lived, using functional assays. METHODOLOGY/PRINCIPAL FINDINGS: Here we used a novel HLA-DR1 tetramer containing a highly targeted CD4+ T cell epitope from the hepatitis C virus non-structural protein 4 to track number and phenotype of hepatitis C virus specific CD4+ T cells in a cohort of seven HLA-DR1 positive patients with acute hepatitis C in comparison to patients with chronic or resolved hepatitis C. We observed peptide-specific T cells in all seven patients with acute hepatitis C regardless of outcome at frequencies up to 0.65% of CD4+ T cells. Among patients who transiently controlled virus replication we observed loss of function, and/or physical deletion of tetramer+ CD4+ T cells before viral recrudescence. In some patients with chronic hepatitis C very low numbers of tetramer+ cells were detectable in peripheral blood, compared to robust responses detected in spontaneous resolvers. Importantly we did not observe escape mutations in this key CD4+ T cell epitope in patients with evolving chronic hepatitis C. CONCLUSIONS/SIGNIFICANCE: During acute hepatitis C a CD4+ T cell response against this epitope is readily induced in most, if not all, HLA-DR1+ patients. This antiviral T cell population becomes functionally impaired or is deleted early in the course of disease in those where viremia persists.

Characterization of sequence variations in immunodominant regions of the HBV-nucleocapsid protein as a prerequisite for the development of an epitope-based vaccine.

BACKGROUND/AIMS: In hepatitis B virus infection, viral elimination is dependent on an efficient antiviral T cell response which is not detectable in chronic hepatitis B. Therefore, new therapeutic concepts focus on T cell activation, such as epitope-based T cell-targeted vaccines. However, with the development of peptide-based vaccines in mind, viral mutations frequently described in hepatitis B within known immunodominant helper epitopes may have an influence on peptide selection. METHODS: Mutant peptides within immunodominant epitopes (aa 1-20, aa 91-105, and aa 143-157) at position 12, 14, 93, 97, 147, 151, 153, and 155 were tested with peripheral blood mononuclear and specific clone cells for their ability to induce proliferation, produce cytokines, induce T cell receptor down-regulation or antagonize wild-type activity of the hepatitis B core antigen-specific CD4+ T cell clones. RESULTS: Five variants could not induce T cell proliferation or cytokine production when the variants were presented alone. Coincubation with wild-type epitopes leads to T cell activation showing that the variants do not act as T cell receptor antagonists for hepatitis B virus-specific CD4+ T cells. In contrast, five other variants and wild-type peptides stimulated CD4+ T cell proliferation and production of Th1 cytokines. CONCLUSIONS: Our data demonstrate that frequently occurring mutations within immunodominant epitopes have rather a nonstimulatory than a strengthening effect and thus should not included in a vaccine.

Vaccine-induced early control of hepatitis C virus infection in chimpanzees fails to impact on hepatic PD-1 and chronicity.

UNLABELLED: Broad T cell and B cell responses to multiple HCV antigens are observed early in individuals who control or clear HCV infection. The prevailing hypothesis has been that similar immune responses induced by prophylactic immunization would reduce acute virus replication and protect exposed individuals from chronic infection. Here, we demonstrate that immunization of naïve chimpanzees with a multicomponent HCV vaccine induced robust HCV-specific immune responses, and that all vaccinees exposed to heterologous chimpanzee-adapted HCV 1b J4 significantly reduced viral RNA in serum by 84%, and in liver by 99% as compared to controls (P=0.024 and 0.028, respectively). However, despite control of HCV in plasma and liver in the acute period, in the chronic phase, 3 of 4 vaccinated animals developed persistent infection. Analysis of expression levels of proinflammatory cytokines in serial hepatic biopsies failed to reveal an association with vaccine outcome. However, expression of IDO, CTLA-4 [corrected] and PD-1 levels in liver correlated with clearance or chronicity. CONCLUSION: Despite early control of virus load, a virus-associated tolerogenic-like state can develop in certain individuals independent of vaccination history.

Extended treatment duration for hepatitis C virus type 1: comparing 48 versus 72 weeks of peginterferon-alfa-2a plus ribavirin.

BACKGROUND & AIMS: The treatment of patients infected with hepatitis C virus (HCV) type 1 remains a challenge necessitating innovative strategies to improve treatment outcome. The extension of treatment duration beyond 48 weeks is one possible strategy to address this problem. METHODS: The efficacy and safety of 48 weeks (group A, N = 230) vs 72 weeks (group B, N = 225) of treatment with pegylated-interferon-alfa-2a (180 microg/wk) plus ribavirin (800 mg/day) were studied in treatment-naive patients with HCV type 1 infection. On-treatment and sustained virologic response (SVR) 24 weeks after stopping treatment was assessed by qualitative reverse-transcription polymerase chain reaction (sensitivity 50 IU/mL). RESULTS: Overall, no significant differences could be observed in the treatment outcome between both groups. End-of-treatment and SVR rates in groups A and B were 71% vs 63% and 53% vs 54%, respectively. Patients with undetectable HCV-RNA levels already at weeks 4 and 12 had excellent SVR rates ranging from 76% to 84% regardless of treatment group, whereas patients shown to be still HCV-RNA positive at week 12 achieved significantly higher SVR rates when treated for 72 instead of 48 weeks (29% vs 17%, P = .040). A particular benefit from extended treatment duration was seen in patients with low-level viremia (<6000 IU/mL) at week 12. The frequency and intensity of adverse events was similar between the 2 groups. CONCLUSIONS: Extended treatment duration generally is not recommended in HCV type 1 infection and should be reserved only for patients with slow virologic response defined as HCV-RNA positive at week 12 but negative at week 24.

Plasmacytoid dendritic cells in acute and chronic hepatitis C virus infection.

Chronic evolution of acute hepatitis C (aHC) occurs in more than 80% of patients but can frequently be prevented by early treatment with interferon (IFN)-alpha. Plasmacytoid dendritic cells (pDCs) are the major endogenous IFN-alpha producers, but their role in aHC is unknown. In this study, frequency, phenotype, and pDC function were analyzed in 13 patients with aHC and 32 patients with chronic hepatitis C (cHC) compared with 20 healthy controls, 33 sustained responders to antiviral treatment, 14 patients with acute hepatitis B (aHB), and 21 patients with nonviral inflammatory disease. In aHC, pDCs in the peripheral blood were significantly reduced compared with healthy controls (median, 0.1% vs. 0.36%, P < .0005) and were inversely correlated to alanine aminotransferase levels (r = -0.823; P < .005). Circulating pDCs in aHC were immature, as determined via reduced expression of HLA-DR and CCR7, and produced little amounts of IFN-alpha (median, 3.5 pg/50,000 peripheral blood mononuclear cells [PBMCs] vs. 498.4 pg/50,000 PBMCs in healthy controls; P < .0005). Less pronounced changes were present in cHC (median, 0.17%, 28.0 pg/50,000 PBMCs IFN-alpha, respectively). However, a significantly reduced frequency and IFN-alpha production was also found in self-limited aHB (median 0.1%, 8.6 pg/50,000 PBMCs) and in patients with nonviral inflammatory disease (median 0.19%, 7.5 pg/50,000 PBMCs). In conclusion, in aHC frequency and IFN-alpha-producing capacity of peripheral blood pDCs are dramatically reduced and inversely correlated with the degree of liver inflammation. In cHC there is incomplete recovery of pDC function, which, however, could be solely due to the chronic inflammatory state.

Uptake and presentation of hepatitis C virus-like particles by human dendritic cells.

Hepatitis C virus (HCV) is a major cause of chronic hepatitis worldwide. Interaction of dendritic cells (DCs) with viral particles may play an important role in the immunopathogenesis of HCV infection. Since the synthesis or purification of infectious virions is limited, we used HCV-like particles (HCV-LPs) to study the interaction of HCV with human DCs. Immature DCs exhibited an envelope-specific and saturable binding of HCV-LPs, indicating receptor-mediated DC-HCV-LP interaction. Confocal microscopy revealed that HCV-LPs were rapidly taken up by DCs in a temperature-dependent manner. Competition experiments demonstrated that C-type lectins such as mannose receptor or DC-SIGN (DC-specific intercellular adhesion molecule 3-grabbing nonintegrin) were not sufficient for mediating HCV-LP binding. HCV-LP uptake was followed by DC activation. DCs pulsed with HCV-LPs stimulated HCV core-specific CD4(+) T cells, indicating that uptake of HCV-LPs by DCs leads to antigen processing and presentation on major histocompatibility complex (MHC) class II molecules. Finally, HCV-LP-derived antigens were efficiently cross-presented to HCV core-specific CD8(+) T cells. These findings demonstrate that HCV-LPs represent a novel model system to study HCV-DC interaction allowing definition of the molecular mechanisms of HCV uptake, DC activation, and antigen presentation to T cells. Furthermore, HCV-LP-mediated DC activation and efficient antigen presentation may explain the marked immunogenicity of HCV-LPs in vivo.

Analysis of a successful HCV-specific CD8+ T cell response in patients with recurrent HCV-infection after orthotopic liver transplantation.

Virus-specific CD8+ T cells play a major role in antiviral immune defenses; their significance in the transplant setting, however, is unclear. In the present study, we asked whether hepatitis C virus (HCV)-specific CD8+ T cells were detectable in the presence of an immunosuppressive treatment and whether the HCV-specific CD8+ T cell response correlates with treatment outcome in patients who receive interferon (IFN)-alpha / ribavirin therapy after orthotopic liver transplantation (OLTx). Liver- and blood-derived T cell lines of 21 patients after OLTx were studied before, at the end of, and after antiviral treatment. Virus-specific IFN-gamma production in response to a panel of previously identified HCV-specific epitopes restricted by the human leukocyte antigen (HLA) class I molecules A2, A3, B7, B35, and B44 of structural and nonstructural HCV protein was determined by enzyme-linked immunospot (ELISPOT) assay. Before treatment, only low numbers of HCV-specific CD8+ T cells were detectable. In 6 patients with a sustained virological response, a significant, multispecific, and sustained CD8+ T cell response was detectable, which was mainly found in the peripheral blood. Nonresponders and transient responders showed undetectable, weak, or transient HCV-specific CD8+ T cell responses. (Sustained responders vs. transient and nonresponders: Wilcoxon rank-signed test; P < .01). In conclusion, our data indicate that despite immunosuppression, HCV-specific CD8+ T cells are detectable in patients with recurrent HCV infection after OLTx and that a significant, multispecific, and long-lasting HCV-specific CD8+ T cell response contributes to viral elimination.

Inhibition of hepatitis C virus-like particle binding to target cells by antiviral antibodies in acute and chronic hepatitis C.

Hepatitis C virus (HCV) is a leading cause of chronic viral hepatitis worldwide. The study of antibody-mediated virus neutralization has been hampered by the lack of an efficient and high-throughput cell culture system for the study of virus neutralization. The HCV structural proteins have been shown to assemble into noninfectious HCV-like particles (HCV-LPs). Similar to serum-derived virions, HCV-LPs bind and enter human hepatocytes and hepatoma cell lines. In this study, we developed an HCV-LP-based model system for a systematic functional analysis of antiviral antibodies from patients with acute or chronic hepatitis C. We demonstrate that cellular HCV-LP binding was specifically inhibited by antiviral antibodies from patients with acute or chronic hepatitis C in a dose-dependent manner. Using a library of homologous overlapping envelope peptides covering the entire HCV envelope, we identified an epitope in the N-terminal E2 region (SQKIQLVNTNGSWHI; amino acid positions 408 to 422) as one target of human antiviral antibodies inhibiting cellular particle binding. Using a large panel of serum samples from patients with acute and chronic hepatitis C, we demonstrated that the presence of antibodies with inhibition of binding activity was not associated with viral clearance. In conclusion, antibody-mediated inhibition of cellular HCV-LP binding represents a convenient system for the functional characterization of human anti-HCV antibodies, allowing the mapping of envelope neutralization epitopes targeted by naturally occurring antiviral antibodies.

Antiviral treatment of recurrent hepatitis C virus (HCV) infection after liver transplantation: association of a strong, multispecific, and long-lasting CD4+ T cell response with HCV-elimination.

BACKGROUND/AIMS: Patients with recurrent hepatitis C virus (HCV)-infection after liver transplantation (OLTx) could develop an early, multispecific, preferentially intrahepatic CD4+ T cell response. We asked now whether there is a correlation between the HCV-specific CD4+ T cell response and treatment outcome in patients who receive interferon (IFN)-alpha/ribavirin. METHODS: Liver- and blood-derived T cell lines of 20 patients were studied in parallel before, under, at the end and after antiviral treatment. Virus-specific IFN-gamma production at a single cell level to HCV-proteins (core, non-structural protein (NS)3/4, NS5) was determined by enzyme-linked immunospot assay. RESULTS: In 6/7 non-responders a weak HCV-specific CD4+ T cell response was detectable. All six sustained responders developed a strong, at NS3/4 and NS5 directed and long-lasting CD4+ T cell response which was mainly detected in peripheral blood mononuclear cells. This reaction was significantly stronger: (1) in the responders than in the non-responders; and (2) within the responders at the end of treatment than before (P<0.03). Seven transient-responders showed a weak and/or transient HCV-specific CD4+ T cell response. CONCLUSIONS: In patients with recurrent HCV-infection after OLTx, who receive antiviral treatment, a strong, at NS3/4 and NS5 directed and long-lasting CD4+ T cell response is associated with HCV-elimination whereas no or a weak/transient response is associated with treatment failure.

Acute hepatitis C: high rate of both spontaneous and treatment-induced viral clearance.

BACKGROUND & AIMS: Acute hepatitis C virus infection accounts for approximately 20% of cases of acute hepatitis today. The aim of this study was to define the natural course of the disease and to contribute to the development of treatment strategies for acute hepatitis C virus. METHODS: The diagnosis of acute hepatitis C virus in 60 patients was based on seroconversion to anti-hepatitis C virus antibodies or clinical and biochemical criteria and on the presence of hepatitis C virus RNA in the first serum sample. RESULTS: Fifty-one of 60 (85%) patients presented with symptomatic acute hepatitis C virus. In the natural (untreated) course of acute symptomatic hepatitis C (n = 46), spontaneous clearance was observed in 24 patients (52%), usually within 12 weeks after the onset of symptoms, whereas all asymptomatic patients (n = 9) developed chronic hepatitis C. The start of antiviral therapy (interferon-alpha with or without ribavirin) beyond 3 months after the onset of acute hepatitis induced sustained viral clearance in 80% of treated patients. CONCLUSIONS: The management of acute hepatitis C has to take into account the high rate of spontaneous viral clearance within 12 weeks after the onset of symptomatic disease. Treatment of only those patients who remain hepatitis C virus RNA positive for more than 3 months after the onset of disease led to an overall viral clearance (self-limited and treatment induced) in 91% of patients, and unnecessary treatment was avoided in those with spontaneous viral clearance. Patients with asymptomatic acute hepatitis C virus infection are unlikely to clear the infection spontaneously and should be treated as early as possible.

Triple therapy with amantadine in treatment-naive patients with chronic hepatitis C: a placebo-controlled trial.

The antiviral efficacy of amantadine in patients with chronic hepatitis C is controversial. In this randomized, prospective, placebo-controlled, multicenter trial, triple therapy with interferon alfa (IFN-alpha)-2a plus ribavirin and amantadine (amantadine group) was compared with combination therapy IFN-alpha plus ribavirin (control group). Four hundred previously untreated patients with histologically proven chronic hepatitis C were randomly allocated to treatment with amantadine sulphate (100 mg twice daily orally) or a matched placebo together with IFN-alpha induction plus ribavirin (1,000-1,200 mg/day orally) for 48 weeks. The primary end point was sustained virologic response (SVR) defined as undetectable serum hepatitis C virus (HCV) RNA (<100 copies/mL) 24 weeks after the end of treatment. SVR was observed in 52% of the amantadine group and in 43.5% of the control group (P =.11). Among patients with HCV genotype 1 infection, the corresponding SVR rates were 39% and 31%, respectively. The virologic on-treatment response rate in week 24 was significantly higher in the amantadine group as compared with the control group (70% vs. 59%, respectively, P =.016). This beneficial effect was mainly related to HCV type 1-infected patients (63% vs. 47%, respectively, P =.012). Independent factors associated with SVR, according to multiple logistic regression analysis, were amantadine treatment, low baseline HCV RNA, platelet counts (>/=250/nL), pretreatment ALT quotient >/=3, and GGT level (<28 U/L) as well as HCV genotypes other than 1. In conclusion, although we could not demonstrate a significant advantage of the triple regimen in univariate analysis, multivariate analysis offers arguments that amantadine should be considered as a potential anti-HCV drug in future studies.

Detection of functionally altered hepatitis C virus-specific CD4 T cells in acute and chronic hepatitis C.

Chronic hepatitis C is characterized by a weak or absent hepatitis C virus (HCV)-specific CD4(+) T-cell response in terms of antigen-specific proliferation or interferon gamma (IFN-gamma) secretion. To clarify whether this is due to the absence or functional impairment of antigen-specific CD4(+) T cells we developed an assay that relies on the induced expression of the T-cell activation marker CD25 and is therefore independent from cytokine secretion or proliferation. In 10 of 20 patients with chronic hepatitis C, a significant number of antigen-specific activated CD4(+) T cells (mean 1.06%/patient; range, 0% to 5.2% of CD4(+) T cells) could be shown, whereas antigen-specific proliferation was present in only 1 of 20 patients. IFN-gamma secretion was absent in all 13 patients tested. However, significant antigen-specific interleukin 10 (IL-10) and transforming growth factor beta (TGF-beta) secretion was present in 6 of 10 and 3 of 10 patients, respectively. In 8 patients with acute hepatitis C, irrespective of disease outcome, HCV-specific CD4(+) T cells were detected in all patients and at a significantly higher frequency (mean 3.7%/patient; range, 1.16% to 7.17%) in the first weeks of disease. A chronic course of disease was associated either with a loss of both IFN-gamma secretion and proliferation, resembling an anergic state, or a loss of T-cell proliferation followed by a rapid decline in IFN-gamma-producing cells, corresponding to exhaustion of the specific immune response. In conclusion, functional changes of HCV-specific CD4(+) T cells or failure to develop a long-lasting T-helper response may contribute to chronic hepatitis C viral persistence.

Hepatitis C virus eradication associated with hepatitis B virus superinfection and development of a hepatitis B virus specific T cell response.

BACKGROUND/AIMS: Specific T cell responses during acute hepatitis B and during chronic hepatitis C have been described in detail. However, the T cell responses during the rare setting of acute hepatitis B virus (HBV) infection in the course of chronic hepatitis C that eventually lead to clearance of both viruses are completely unknown. METHODS: We analyzed the virus specific CD4+ and CD8+ T cell response during an acute HBV superinfection in a patient with chronic hepatitis C. RESULTS: The patient eliminated hepatitis C virus (HCV)-RNA and HBV-DNA from serum soon after the clinical onset of acute hepatitis B. The HBV specific T cell response found in this patient corresponds to the typical response that has been described in acute hepatitis B without chronic HCV infection. In contrast the hepatitis C specific immune response was similar to that generally found in chronic hepatitis C despite the fact that the patient also eliminated HCV-RNA. CONCLUSIONS: We hypothesize that the acute HBV infection induced a HBV specific T cell response which was associated with elimination HBV DNA and HCV-RNA, the latter possibly by bystander mechanisms, e.g. via secretion of cytokines. If such a non-specific bystander mechanism which has proven to be effective in the experimental setting and which is formally described here for a single patient can be shown to be a more general phenomenon, it may support the approach with new antiviral strategies, e.g. the induction of non-specific defense mechanisms against HCV.

Measurement of serum beta-crosslaps is influenced by proteolytic conditions.

Serum beta-crosslaps are an established laboratory test to investigate bone metabolism. However, lytic conditions may affect the measurement of serum beta-crosslaps. Therefore, we investigated the effect of cathepsin C and human leukocyte lysate on serum beta-crosslaps in relation to temperature and time. We divided eight serum samples with elevated beta-crosslaps levels into three aliquots and stored them at 4, 21 and 37 degrees C. Another five serum samples were divided into three aliquots and adjusted to contain different cathepsin C concentrations (50, 250, 500 IU/l). These aliquots were divided again and stored at 4, 21 and 37 degrees C. Finally, three aliquots from three additional serum samples were treated with human leukocyte lysate (100, 300, 500 microl), divided again and stored at 4, 21 and 37 degrees C. Measurements of serum beta-crosslaps were then carried out before and immediately after manipulation, and after 2 and 5 days of storage. When stored at 21 degrees C, serum beta-crosslaps diminished significantly (25% after 5 days), but no significant change was detectable when they were stored at 4 degrees C. Cathepsin C induced up to a 14% increase in beta-crosslaps while human leukocyte lysate caused up to a 17% decrease. This study demonstrates that the influence of proteolytic conditions on the serum concentration of beta-crosslaps is not uniform. Leukocyte lysate decreased serum beta-crosslaps while the addition of cathepsin C increased their concentration. Therefore, serum should be separated from the whole blood immediately after coagulation and stored until analysis in a deep freezer.

Immunological monitoring during therapeutic vaccination as a prerequisite for the design of new effective therapies: induction of a vaccine-specific CD4+ T-cell proliferative response in chronic hepatitis B carriers.

We characterized the anti-viral T-cell response in 22 chronically infected patients, who participated in a European multi-center randomized placebo-controlled, double-blind study therapeutic vaccination trial with pre-S1, pre-S2 and S antigenic components of the hepatitis B virus (HBV). It induced a significant HBsAg-specific T-cell proliferation and the production of Th2-cytokines (i.e. IL-5). A specific induction of Th1-lymphokines was not detectable although this has been demonstrated in this study in response to the nucleocapsid protein (HBcAg). Further analysis indicated that this approach does not activate HBV-specific CD8+ T-lymphocytes as detected by ELISPOT-assay. Our results might explain why a specific therapeutic vaccine, although safe and well-tolerated is not always able to break tolerance leading to the clearance of the hepatitis B virus.

Memory CD8+ T cells vary in differentiation phenotype in different persistent virus infections.

The viruses HIV-1, Epstein-Barr virus (EBV), cytomegalovirus (CMV) and hepatitis C virus (HCV) are characterized by the establishment of lifelong infection in the human host, where their replication is thought to be tightly controlled by virus-specific CD8+ T cells. Here we present detailed studies of the differentiation phenotype of these cells, which can be separated into three distinct subsets based on expression of the costimulatory receptors CD28 and CD27. Whereas CD8+ T cells specific for HIV, EBV and HCV exhibit similar characteristics during primary infection, there are significant enrichments at different stages of cellular differentiation in the chronic phase of persistent infection according to the viral specificity, which suggests that distinct memory T-cell populations are established in different virus infections. These findings challenge the current definitions of memory and effector subsets in humans, and suggest that ascribing effector and memory functions to subsets with different differentiation phenotypes is no longer appropriate.

Immunology of hepatitis B infection.

The immune response initiated by the T-cell response to viral antigens is thought to be fundamental for viral clearance and disease pathogenesis in hepatitis B virus (HBV) infection. The T-cell response during acute self-limited hepatitis B in people is characterised by a vigorous, polyclonal, and multispecific cytotoxic and helper-T-cell response. By contrast, the immune response in chronic carriers, not able to eliminate the virus, is weak or undetectable. Thus a dominant cause of viral persistence could be the existence of a weak antiviral immune response. Methodological progress in animal models allows more precise investigation of the mechanisms by which the immune system resolves viral infection or develops chronic infection. Although clearance of most virus infections is widely thought to indicate the killing of infected cells by virus-specific T cells, data suggest that non-cytolytic intracellular viral inactivation by cytokines released by virus-inactivated lymphomononuclear cells could have an important role in the clearance of this virus without killing the infected cell. Additional factors that could contribute to viral persistence, which have been partly proven in animal models, are viral inhibition of antigen processing or presentation, modulation of the response to cytotoxic mediators, immunological tolerance to viral antigens, viral mutations, and infection of immunologically privileged sites. In view of the central role of cellular immunity in disease pathogenesis, strategies have been proposed to manipulate this cellular immune response in favour of protection from disease.

Antibody responses against B-cell epitopes of the hypervariable region 1 of hepatitis C virus in self-limiting and chronic human hepatitis C followed-up using consensus peptides.

A rare collection of serum samples from patients with hepatitis C virus (HCV) infection followed up from the onset of clinical symptoms was acquired. RNA corresponding to the hypervariable region 1 (HVR1) of E2 protein of HCV isolated from nine patients was reverse-transcribed, amplified, sequenced, and HVR1 amino acid sequences were deduced. These sequences and a selection of HVR1 amino acid sequences of matching HCV genotypes from protein and translated DNA sequence databanks were used to create the HVR1 amino acid consensus. The degenerated peptides mimicking N- and C-termini of the consensus were synthesized. Most (76%) of 17 patients followed up for the period from 1 week to a minimum of 7 months from the onset of acute symptoms developed antibodies reacting with peptides representing N- and/or C- termini of HVR1. Antibody recognition of the consensus HVR1 peptides indicates that the variability of HVR1 sequence on the protein level is limited with certain conserved structure(s) being untouched. A tendency was observed for a slower development of anti-HVR1 antibody response in patients developing chronic HCV, as compared to those with self-limiting HCV infection.