Cellular immunity to hepatitis C virus core protein and the response to interferon in patients with chronic hepatitis C

Combination of three adjuvants enhances the immunogenicity of a recombinant protein containing the CTL epitopes of non-structural proteins of hepatitis C virus

Hepatitis C virus (HCV) can cause chronic infection and evade the immune response. The generation and maintenance of an effective T-cell response is important for immune-mediated control of HCV infection. The purpose of this study was to obtain recombinant mosaic proteins containing the cytotoxic T lymphocyte (CTL) epitopes of HCV fused with different adjuvants and analyse their immunogenicity. A recombinant polyepitope protein comprising HLA-A2-restricted CTL epitopes of the NS3, NS4ab and NS5a proteins of HCV was designed. Adjuvant compounds, the T-helper (Th) epitope PADRE, lipopeptide from Neisseria meningiditis and interleukin 2 (IL-2) were included in the fusion proteins. Three proteins differing in their adjuvant content were expressed in Escherichia coli and purified. The purified proteins formed nanosized particles. The proteins were characterized by their ability to cause proliferation of spleen cells, induce expression of cytokine genes and production of interferon gamma by T lymphocytes of immunized mice. The obtained recombinant vaccine proteins effectively stimulate dendritic cells, which in turn specifically activate Th1 and Th2 lymphocytes. Adjuvant components act additively to enhance the stimulation of dendritic cells and polarize them in the direction of Th1 lymphocyte activation. Analysis of spleen cell proliferation, expression of Th1 and Th2 cytokines and production of interferon gamma by lymphocytes of immunized mice after specific stimulation in vitro revealed that recombinant protein comprising CTL epitopes of HCV, Th epitope PADRE, lipoprotein and IL-2 induced the highest response of T-lymphocytes.

Role of LncRNA-AF085935, IL-10 and IL-17 in Rheumatoid Arthritis Patients With Chronic Hepatitis C

BACKGROUND

The current study aimed at testing the effect of corticosteroid therapy on serum levels of interleukin-10 (IL-10) and IL-17 as well as lncRNA-AF085935 in patients of rheumatoid arthritis (RA) associated with hepatitis C virus (HCV) and evaluating the usefulness of using these parameters to predict the therapeutic efficacy of steroids in these patients.

METHODS

Thirty healthy control subjects and 65 chronic HCV patients with RA were included in our study. Patients were subjected to clinical examination, abdominal ultrasound, and liver biopsy and received 6-methyl-prednisolone (PDN) 16 mg/day for 48 weeks. Blood samples were collected from all subjects and serum was separated to assess IL-10 and IL-17 by ELISA and HCV RNA and lncRNA-AF085935 by qRT-PCR.

RESULTS

Our study revealed that there were significant increases in serum levels of IL-10, IL-17 and lncRNA-AF085935 in RA patients associated with HCV compared with healthy control subjects. Also there were significant increases in serum levels of IL-10 and HCV RNA and a significant decrease in serum level of IL-17 in patients after corticosteroid therapy, while lncRNA-AF085935 is not significantly changed.

CONCLUSION

LncRNA-AF085935 might be a useful candidate biomarker for the early detection of RA associated with HCV, providing potential new strategies for early screening and therapy of these patients. IL-17 is a non-invasive prognostic marker to predict the efficacy of corticosteroid therapy in RA patients associated with chronic hepatitis C.

Levels of Schistosoma mansoni Circulating Antigen in Chronic Hepatitis C Patients with Different Stages of Liver Fibrosis

The goal of this study was to determine the levels of S. mansoni antigen in different liver fibrosis stages with chronic hepatitis C (CHC) Egyptian patients. A total of 174 CHC patients showing HCV-NS4 antigen and HCV- RNA in their sera were included. S. mansoni antigen was detected in serum using Western blot and ELISA. The levels of interferon-γ (IFN- γ) were determined using ELISA. The 50 kDa S. mansoni antigen discriminated patients infected with S. mansoni from healthy individuals with 0.93 area under curve (AUC), 92% sensitivity, and 97% specificity. The level of S. mansoni antigen (μg/ml) was significantly (P < 0.0001) increased with the progression of liver fibrosis stages (26.9 ± 17.5 in F1, 42.1 ± 25.2 in F2, 49.8 ± 30.3 in F3 and 62.2 ± 26.3 μg/mL in F4 liver cirrhosis), 26.9 ± 17.59 in significant fibrosis (F2-F4); 51.2 ± 27.9 in advanced fibrosis (F3-F4). A significant correlation (r = 0.506; P < 0.0001) was shown between the levels of the S. mansoni antigen and the HCV-NS4 antigen. In conclusion, the presence of S. mansoni antigen in different liver fibrosis stages of CHC patients confirming that concomitant schistosome infection aggravates liver disease.

Interleukin 10 gene single nucleotide polymorphisms in Polish patients with chronic hepatitis C: Analysis of association with severity of disease and treatment outcome

It is suggested that interleukin 10 (IL-10), as a modulator of immune response, is likely to influence the elimination of hepatitis C virus (HCV), the progression of chronic hepatitis C (CHC) and the response to interferon-based therapy in CHC patients. The aim of the study was to analyze the association of single nucleotide polymorphisms (SNPs) of IL-10 gene with severity of liver disease (degree of inflammation and stage of fibrosis) and outcome of pegylated interferon alpha and ribavirin combined therapy (sustained virological response (SVR) and relapse) in 196 Polish CHC patients infected with HCV genotype 1. The analysis included IL-10 promoter SNPs: -1082(A/G) rs1800896, -819(C/T) rs1800871, -592(C/A) rs1800872 and SNP in the 3' UTR of IL-10 gene: +4529(A/G) rs3024498. Genotyping was performed using PCR-RFLP and HRM analysis. It was demonstrated that the -592C allele is associated with mild hepatic inflammation. Moreover, it was found that the -819C allele might be associated with SVR and that the ACCA haplotype and intermediate IL-10 producer ACC haplotype are associated with SVR and non-relapse. It can be concluded that IL-10 SNPs are associated with severity of disease and response to therapy and may be considered as potential prognostic and predictive markers in CHC.

Selection of conserved epitopes from hepatitis C virus for pan-populational stimulation of T-cell responses

The hepatitis C virus (HCV) is able to persist as a chronic infection, which can lead to cirrhosis and liver cancer. There is evidence that clearance of HCV is linked to strong responses by CD8 cytotoxic T lymphocytes (CTLs), suggesting that eliciting CTL responses against HCV through an epitope-based vaccine could prove an effective means of immunization. However, HCV genomic plasticity as well as the polymorphisms of HLA I molecules restricting CD8 T-cell responses challenges the selection of epitopes for a widely protective vaccine. Here, we devised an approach to overcome these limitations. From available databases, we first collected a set of 245 HCV-specific CD8 T-cell epitopes, all known to be targeted in the course of a natural infection in humans. After a sequence variability analysis, we next identified 17 highly invariant epitopes. Subsequently, we predicted the epitope HLA I binding profiles that determine their potential presentation and recognition. Finally, using the relevant HLA I-genetic frequencies, we identified various epitope subsets encompassing 6 conserved HCV-specific CTL epitopes each predicted to elicit an effective T-cell response in any individual regardless of their HLA I background. We implemented this epitope selection approach for free public use at the EPISOPT web server.

Induction of potent protection against acute and latent herpes simplex virus infection in mice vaccinated with dendritic cells

BACKGROUND AIMS

Dendritic cells (DCs) are the most potent antigen presenting cells of the immune system and have been under intense study with regard to their use in immunotherapy against cancer and infectious disease agents. In the present study, DCs were employed to assess their value in protection against live virus challenge in an experimental model using lethal and latent herpes simplex virus (HSV) infection in Balb/c mice.

METHODS

DCs obtained ex vivo in the presence of granulocyte-macrophage colony-stimulating factor and interleukin-4 were loaded with HSV-1 proteins (DC/HSV-1 vaccine). Groups of mice were vaccinated twice, 7 days apart, via subcutaneous, intraperitoneal or intramuscular routes with DC/HSV-1 and with mock (DC without virus protein) and positive (alum adjuvanted HSV-1 proteins [HSV-1/ALH]) control vaccines. After measuring anti-HSV-1 antibody levels in blood samples, mice were given live HSV-1 intraperitoneally or via ear pinna to assess the protection level of the vaccines with respect to lethal or latent infection challenge.

RESULTS

Intramuscular, but not subcutaneous or intraperitoneal, administration of DC/HSV-1 vaccine provided complete protection against lethal challenge and establishment of latent infection as assessed by death and virus recovery from the trigeminal ganglia. It was also shown that the immunity was not associated with antibody production because DC/HSV-1 vaccine, as opposed to HSV-1/ALH vaccine, produced very little, if any, HSV-1-specific antibody.

CONCLUSIONS

Overall, our results may have some impact on the design of vaccines against genital HSV as well as chronic viral infections such as hepatitis B virus, hepatitis C virus and human immunodeficiency virus.

Polymorphisms in interleukin-10 and interleukin-28B genes in Egyptian patients with chronic hepatitis C virus genotype 4 and their effect on the response to pegylated interferon/ribavirin-therapy

BACKGROUND AND AIM

Recently, it has been suggested that single nucleotide polymorphisms (SNPs) in some cytokine genes may influence the production of the associated cytokines that affect the host immune response to pegylated interferon-α (Peg-IFN-α) with ribavirin (RBV) in hepatitis C virus (HCV) patients. The aim of the present study was to investigate the possible role of the SNPs of IL-10 and Il-28B and their serum levels in predicting the response to treatment of HCV-4.

METHODS

Egyptian patients were treated with Peg-IFN-α/RBV. A total of 100 HCV genotype 4-infected patients and 80 healthy control subjects were included in the present study. SNPs in the IL-10 (-592 A/C and -819 T/C) and IL-28B (rs8099917 T/G and rs12979860 C/T) genes and their serum levels were assessed. The IL-10-592-CC, IL-28-rs8099917-TT and IL-28-rs12979860-CC genotypes were significantly higher in responders than in non-responders.

RESULTS

Interestingly, the serum levels of IL-10 were significantly increased; in contrast, the serum levels of Il-28B were significantly decreased in HCV patients compared with normal patients. Polymorphisms in IL-28B are more sensitive (P < 0.001) than those in IL-10-592 (P = 0.03). However, the serum level of IL-10 is higher than that of IL-28, and this difference can serve as a prognostic marker using a receiver operator characteristic (ROC) analysis.

CONCLUSIONS

It can be concluded that SNPs in IL-28B and the serum levels of Il-10 and IL-28 may be promising predictors for HCV therapy.

Rapid early innate control of hepatitis C virus during IFN-α treatment compromises adaptive CD4+ T-cell immunity

The ability to control HCV with IFN-α-based treatments provides an opportunity in humans to study how the rate of viral clearance in vivo impinges on the development of antiviral responses. Ex vivo (IFN-γ-producing) and cultured antiviral CD4⁺ T cells, serum cytokines, and viral loads were measured repeatedly in a cohort of chronically HCV-infected subjects (n = 33) receiving IFN-α. Rapid control of virus indicated by an increased calculated rate of virus clearance, occurred in those subjects demonstrating absent/minimal T-cell responses (p < 0.0006). Surprisingly, in subjects who demonstrated the most robust T-cell responses (and reduced serum IL-10), there was actually a reduced rate of early virus clearance. A subsequent analysis of NK-cell function in available subjects (n = 8) revealed an inverse correlation between pretreatment NK-cell expression of NKp46 and the potential to upregulate cytotoxic function on exposure to IFN-α (p < 0.004), as well as the subsequent measured rate of viral clearance (p = 0.045). Thus, the CD4⁺ T-cell response during IFN-α treatment appears to be shaped by the rate of innate virus suppression. These data suggest that individuals who respond most effectively to immune intervention may be most in need of subsequent vaccination to prevent reinfection.

The evaluation of hepatitis C virus core antigen in immunized BALB/c mice

BACKGROUND

Hepatitis infection represents one of the important causes of morbidity and mortality in developing countries, however there is not any effective vaccine against hepatitis C which is one of the significant problems in vaccine project.

OBJECTIVES

The aim of the present study is to evaluate the role of HCV core protein in inducing IFN-Gamma secretion and TCL activities as a vaccine in Balb/C mice.

MATERIAL AND METHODS

Our previous cloned plasmid (HCV Core gene into pETDuet-1) applied for protein expression in bacteria. The expressed and purified recombinant protein together with Freund's adjuvant was injected to 15 Balb/c mice. The total IgG and IgG2a of immunized mice sera were evaluated after a week. Two weeks after booster injection, we studied the proliferation and IFNγ secretion of spleens, inguinal and popliteal lymph nodes lymphocytes by ELISA and ELISPOT.

RESULTS

The FSFC (Frequency of spot forming cells) of secreting cells of immunized mice with HCV/Core protein and sera IgG2a were considerably higher than the control groups.

CONCLUSIONS

The core protein together with proper adjuvant can be a candidate vaccine against of HCV infection.

Is interleukin-10 gene polymorphism a predictive marker in HCV infection?

The clinical outcome of hepatitis C virus (HCV) infection varies between individuals - from spontaneous viral clearance and persistence without complication, to chronic hepatitis, cirrhosis and hepatocellular carcinoma. Also patterns of response to interferon-based anti-HCV therapy are different from person to person. This diversity may be affected by host genetic factors, including alterations in genes encoding cytokines. Interleukin-10, as an anti-inflammatory cytokine and immune response modulator, may influence on HCV infection susceptibility as well as spontaneous and treatment-induced HCV eradication. Moreover, it is stated that IL-10 has antifibrotic properties and play a role in progression of liver disease. This review summarized studies on interleukin-10 gene polymorphisms (mainly promoter SNPs at positions -1082(G/A), -819(C/T) and -592(C/A)), which may determine IL-10 production, regarding susceptibility to HCV infection, course of HCV-related liver disease (fibrosis, cirrhosis, hepatocellular carcinoma, ALT abnormalities), spontaneous viral elimination as well as hepatitis C treatment outcomes. Analysis of hereby summarized studies shows that it is difficult to unambiguously determine the importance of IL-10 polymorphism as a predictor of clinical outcome of hepatitis C and response to anti-HCV therapy before its beginning. Thus, future larger studies need to address these issues. Continuation of studies on interleukin-10 polymorphisms as well as identification of other candidate predictive markers in HCV infection has important practical implications and there is a chance that may contribute to reduce the scale of hepatitis C problem.

Advances in hepatitis C virus vaccines, Part one: Advances in basic knowledge for hepatitis C virus vaccine design

INTRODUCTION

Around 3% of the world population is infected with HCV, with 3 - 4 million newly infected subjects added to this reservoir every year. At least 10% of these people will develop liver cirrhosis or cancer over time, while no approved vaccine against HCV infection is available to date.

AREAS COVERED

This paper includes a detailed and correlated patent (selected by HCAPLUS search database) and literature (searched by PubMed) review on the HCV genome, proteins and key epitopes (including underestimated HCV proteins, alternate reading frame proteins), HCV immunology, immunosuppressive mechanisms and protective correlations of immunity in acute and chronic states of infection (features for prophylactic and therapeutic HCV vaccine design), recent HCV cell culture systems (HCV/JFH1) and animal models. In part two of this review, advances in HCV vaccine formulations and modalities as well as a detailed list of the current trials for HCV vaccine and discussion of the pros and cones of different strategies will be provided.

EXPERT OPINION

By using the advanced basic knowledge and tools obtained about HCV vaccinology in recent years and the application of novel formulations and modalities, at least partially effective vaccines will become available in the near future to prevent (or treat) the chronic (if not the acute) state of HCV infection. A few of such vaccines are already in clinical trials.

Interferon combination therapy for HIV/hepatitis C virus coinfection

IFN-α has been the cornerstone of chronic hepatitis C virus (HCV) treatment for over a decade. Yet, rates of sustained virologic response of HCV infection to interferon-based therapy, particularly in difficult-to-treat populations, have been disappointingly low. This is particularly true in HIV/HCV coinfection, in which less than a third of patients typically respond to therapy. New HCV protease inhibitors, most of which will need to be administered with pegylated interferon, are in development, but comprehensive, long-term data for their use in coinfected patients is not yet available. Understanding the basis of this population's poor response to interferon-based therapy is crucial to future exploration of new therapeutic options, immunotherapy and prognosis in HIV/HCV-coinfected population.

A new insight into hepatitis C vaccine development

Chronic hepatitis C virus (HCV) infection remains a serious burden to public health worldwide. Currently, HCV-infected patients could undergo antiviral therapy by giving pegylated IFN-α with ribavirin. However, this therapy is only effective in around 50% of patients with HCV genotype 1, which accounts for more than 70% of all HCV infection, and it is not well tolerated for most patients. Moreover, there is no vaccine available. The efforts on identifying protective immunity against HCV have progressed recently. Neutralizing antibodies and robust T cell responses including both CD4⁺ and CD8⁺ have been shown to be related to the clearance of HCV, which have shed lights on the potential success of HCV vaccines. There are many vaccines developed and tested before entering clinical trials. Here, we would first discuss strategies of viral immune evasion and correlates of protective host immunity and finally review some prospective vaccine approaches against chronic HCV infection.

T-cell responses at baseline and during therapy with peginterferon-alpha and ribavirin are not associated with outcome in chronic hepatitis C infected patients

BACKGROUND

Since the association between hepatitis C virus (HCV)-specific T-cell responses both pre-treatment and during interferon-alpha based therapy and viral clearance is unresolved, a combined analysis of distinctive T-cell characteristics (proliferation and interferon-gamma production) is important to clarify this issue.

METHODS

Peripheral blood mononuclear cells (PBMC) collected in 22 chronic HCV infected patients at pre-treatment and at week 4 during pegIFN-alpha/ribavirin therapy, were stimulated with overlapping peptide pools in a [3H]-thymidine assay, an interferon-gamma-ELISA, and a sensitive 12-day T-cell expansion assay.

RESULTS

Compared to the [3H]-thymidine proliferation and interferon-gamma secretion assays, the 12-day T-cell expansion assay was more sensitive in detecting T-cell responses. No significant association was demonstrated between pre-treatment HCV-specific CD4+ or CD8+ T-cell responses and either a sustained virological response (SVR) or a rapid virological response (RVR). However, a skewing of individual responses towards the non-structural antigens was observed. During pegIFN-alpha/ribavirin therapy, HCV-specific CD4+ and CD8+ T-cells declined similarly in both SVR/RVR and non-SVR/non-RVR patients.

CONCLUSION

No correlation was found between the magnitude of pre-treatment HCV-specific T-cell responses and the outcome of pegIFN-alpha/ribavirin therapy in terms of SVR and RVR. Moreover, the magnitude of HCV-specific T-cell responses declined in all patients early during treatment.

Interleukin-10 promoter polymorphisms in hepatitis C patients with and without Schistosoma mansoni co-infection

BACKGROUND/AIM

Interleukin (IL-10) plays a major role in chronic hepatitis C virus (HCV) disease pathogenesis, in particular in Schistosoma mansoni (S. mansoni) co-infected patients. Given that interindividual variations in IL-10 production are influenced by functional polymorphisms in the IL-10 gene promoter, we determined the frequencies of common (-1082, -819 and -592) IL-10 promoter polymorphisms in chronic HCV patients with and without S. mansoni co-infection and healthy controls, and investigated their association with the degree of histological activity index (HAI) and response to interferon-ribavirin therapy.

METHODS

Genomic DNA from 99 patients and 62 healthy controls, born in the same geographical hyperendemic area, was studied by the polymerase chain reaction, followed by restriction enzyme digestion. Sera were assessed for S. mansoni antibodies.

RESULTS

The frequencies of IL-10 polymorphisms at positions -1082, -819 and -592 from the transcription start site were comparable between HCV patients and controls, as well as between HCV mono-infected and either S. mansoni co-infected patients or controls. The grade of inflammation and the stage of fibrosis showed no association with IL-10 polymorphisms. The frequencies of S. mansoni co-infection and IL-10 genotypes/haplotypes were insignificantly different between non-responders and responders to combination therapy. No effect of other factors like age, gender, HAI group scores and serum alanine aminotransferase and aspartate aminotransferase levels was observed on response to therapy in our patients.

CONCLUSION

Our findings suggest that common IL-10 (-1082, -819 and -592) genotypes/haplotypes do not influence the degree of HAI and response to combination therapy or susceptibility to HCV infection with and without S. mansoni co-infection.

Comparisons of CD8+ T cells specific for human immunodeficiency virus, hepatitis C virus, and cytomegalovirus reveal differences in frequency, immunodominance, phenotype, and interleukin-2 responsiveness

To better understand the components of an effective immune response to human immunodeficiency virus (HIV), the CD8(+) T-cell responses to HIV, hepatitis C virus (HCV), and cytomegalovirus (CMV) were compared with regard to frequency, immunodominance, phenotype, and interleukin-2 (IL-2) responsiveness. Responses were examined in rare patients exhibiting durable immune-mediated control over HIV, termed long-term nonprogressors (LTNP) or elite controllers, and patients with progressive HIV infection (progressors). The magnitude of the virus-specific CD8(+) T-cell response targeting HIV, CMV, and HCV was not significantly different between LTNP and progressors, even though their capacity to proliferate to HIV antigens was preserved only in LTNP. In contrast to HIV-specific CD8(+) T-cell responses of LTNP, HLA B5701-restricted responses within CMV pp65 were rare and did not dominate the total CMV-specific response. Virus-specific CD8(+) T cells were predominantly CD27(+)45RO(+) for HIV and CD27(-)45RA(+) for CMV; however, these phenotypes were highly variable and heavily influenced by the degree of viremia. Although IL-2 induced significant expansions of CMV-specific CD8(+) T cells in LTNP and progressors by increasing both the numbers of cells entering the proliferating pool and the number of divisions, the proliferative capacity of a significant proportion of HIV-specific CD8(+) T cells was not restored with exogenous IL-2. These results suggest that immunodominance by HLA B5701-restricted cells is specific to HIV infection in LTNP and is not a feature of responses to other chronic viral infections. They also suggest that poor responsiveness to IL-2 is a property of HIV-specific CD8(+) T cells of progressors that is not shared with responses to other viruses over which immunologic control is maintained.

The effect of controlled therapy interruption in chronic HCV infection: enhanced host immune response? A hypothesis

BACKGROUND

We have hypothesized that prolonged viral suppression partially reverses immune tolerance in chronic hepatitis C virus infection. Brief periods of treatment interruption can then simulate 'auto-vaccination' and evoke powerful secondary host immune responses.

OBJECTIVE

To determine the effect of controlled therapy interruption CTI on viral load in previous relapsers to interferon and ribavirin treatment.

STUDY DESIGN

Virus is maintained at undetectable levels for 2-8 weeks with pegylated interferon and ribavirin and then briefly interrupted, restarting as soon as viremia returns (cycle 1). It is suppressed for at least a further 4 weeks, then briefly interrupted again (cycle 2).

RESULTS

Viremia relapsed within 2-4 weeks (time to relapse TTR) after the first treatment interruption in all four patients in cycle 1. TTR increased sevenfold with the second treatment interruption in patient 1 and was followed by sustained virological response with cycle 3. In patient 2, TTR increased threefold after cycle 2 and subsequent cycles. Serum ALT and bilirubin rose significantly with treatment interruption during cycles 2 and 3, returning to baseline with treatment resumption. Serum bilirubin rose to 12.3mg/dl when two doses of pegylated interferon were missed during cycle 4. In patients 3 and 4, TTR was unchanged after three consecutive cycles. However, VL has remained more than 1 log below baseline for up to 18 months in both.

CONCLUSIONS

These observations suggest that CTI exerts significant control of chronic hepatitis C viremia.

Monocyte-derived dendritic cells from HCV-infected patients transduced with an adenovirus expressing NS3 are functional when stimulated with the TLR3 ligand poly(I:C)

Dendritic cells (DC) transfected with an adenovirus encoding hepatitis C virus (HCV) NS3 protein (AdNS3) induce potent antiviral immune responses when used to immunize mice. However, in HCV infected patients, controversial results have been reported regarding the functional properties of monocyte-derived DC (MoDC), a cell population commonly used in DC vaccination protocols. Thus, with the aim of future vaccination studies we decided to characterize MoDC from HCV patients transfected with AdNS3 and stimulated with the TLR3 ligand poly(I:C). Phenotypic and functional properties of these cells were compared with those from MoDC obtained from uninfected individuals. PCR analysis showed that HCV RNA was negative in MoDC from patients after the culture period. Also, phenotypic analysis of these cells showed lower expression of CD80, CD86, and CD40, but similar expression of HLA-DR molecules as compared to MoDC from uninfected individuals. Functional assays of MoDC obtained from patients and controls showed a similar ability to activate allogeneic lymphocytes or to produce IL-12 and IL-10, although lower IFN-alpha levels were produced by cells from HCV patients after poly(I:C) stimulation. Moreover, both groups of MoDC induced similar profiles of IFN-gamma and IL-5 after stimulation of allogeneic T-cells. Finally, migration assays did not reveal any difference in their ability to respond to CCL21 chemokine. In conclusion, MoDC from HCV patients are functional after transduction with AdNS3 and stimulation with poly(I:C). These findings suggest that these cells may be useful for therapeutic vaccination in chronic HCV infection.

Increased soluble IL-2 receptor levels during interferon and ribavirin treatment are associated with a good response in genotype 2a/2b patients with chronic hepatitis C

OBJECTIVES

Serum levels of soluble interleukin-2 receptor (sIL-2R) are known to serve as a marker for the activation of T lymphocytes. We measured serum levels of sIL-2R in patients with chronic hepatitis C (CHC) during interferon (IFN)-based treatment to determine the correlation between those levels and therapeutic efficacy, and to clarify whether there is a difference in the activation of T lymphocytes among HCV genotypes after the treatment.

METHODS

Forty-four patients received IFN-alpha2b monotherapy (group IFN-M), whereas 82 patients received the combination therapy with IFN-alpha2b and ribavirin (group IFN+R). We measured serum sIL-2R levels in these patients before (T0) and 2 weeks (T2) after the treatment.

RESULTS

The sustained virologic response rates in genotype 2a/2b patients were significantly higher than those in genotype 1b patients in both groups (P<0.005). In sustained virologic responders, sIL-2R levels at T2 were significantly higher than those at T0 in both groups (P<0.001). In nonresponders, sIL-2R levels at T2 were not different from those at T0 in group IFN-M, but were significantly higher than those at T0 in group IFN+R (P=0.0072). In genotype 1b patients, sIL-2R levels at T2 were not different from those at T0 in group IFN-M, but were significantly higher than those at T0 in group IFN+R (P=0.0064). In genotype 2a/2b patients, sIL-2R levels at T2 were significantly higher than those at T0 in both groups (P<0.0005).

CONCLUSION

These findings suggest that the activation of T lymphocytes after IFN-based treatment contributes to a high-sustained virologic response rate, especially in genotype 2a/2b patients.

HCV-specific T-cell response in relation to viral kinetics and treatment outcome (DITTO-HCV project)

BACKGROUND & AIMS

The second slope of viral decline induced by interferon treatment has been suggested to be influenced mainly by the hepatitis C virus (HCV)-specific T-cell response; however, this hypothesis needs to be validated by results derived from experimental studies.

METHODS

To address this issue, the HCV-specific T-cell response of 32 genotype-1-infected patients of the 270 patients enrolled in the dynamically individualized treatment of hepatitis C infection and correlates of viral/host dynamics phase III, open-label, randomized, multicenter trial was studied in relation to viral kinetics and treatment outcome.

RESULTS

Greater proliferative responses by HCV-specific CD8 cells were found before treatment in patients with a fast viral decline and with a sustained viral response. However, no significant improvement of HCV-specific CD8 responses was observed in the first weeks of therapy in both rapid viral responder and non-rapid viral responder patients. A mild enhancement of proliferative T-cell responses and a partial restoration of the cytotoxic T-cell potential was expressed only late during treatment, likely favored by HCV clearance.

CONCLUSIONS

Early restoration of an efficient T-cell response does not seem to be an essential requirement for a rapid viral decline in the first weeks of treatment. However, patients presenting a better HCV-specific CD8 cell proliferative potential at baseline are more likely to present a rapid and sustained viral response. Therefore, future treatment protocols should consider the development of strategies aimed at improving HCV-specific T-cell responses.

Neutralizing antibodies in patients with chronic hepatitis C infection treated with (Peg)-interferon/ribavirin

BACKGROUND

The role of neutralizing antibody (NAb) in determining response to antiviral therapy has not been established.

OBJECTIVE

In this study we have analysed the kinetic's of the NAb response in patients with chronic hepatitis C who received antiviral therapy.

STUDY DESIGN

Seventeen patients infected with genotype 1, 2a/c or 3a hepatitis C virus (HCV) were enrolled, eight with a sustained virological response (SVR), five non-responders and four relapsers.

RESULTS

The mean NAb titre required to neutralize 50% of the E1E2-pp in patients who achieved an SVR (294+/-S.D. 51), in relapsers (246+/-S.D. 61.7) and non-responders (286+/-S.D. 80.95) did not differ significantly between the patient groups and did not alter during the course of treatment (P>0.01). Genetic variation present before antiviral therapy was analysed by single strand conformation polymorphism (SSCP) and failed to demonstrate a significant difference in the mean number of amplified E1E2 DNA fragments from the serum of patients who achieved an SVR (3.15+/-S.D. 1.53), relapsers (2.8+/-S.D. 1.32) or non-responders (3.69+/-S.D. 1.75). The baseline serum HCV viral loads were also not significantly different between patients who achieved an SVR (1.4 x 10(6) copies/ml; +/-S.D. 2.4 x 10(6)), relapsers (1.3 x 10(7) copies/ml; +/-S.D. 2.4 x 10(7)) and non-responders (1.5 x 10(6) copies/ml; +/-S.D. 1.1 x 10(6)).

CONCLUSION

We have shown that neutralizing anti-HCVpp antibody is not associated with response to antiviral therapy. In addition, there was no correlation between baseline virological load, circulating viral quasi-species, NAb titres and final response to treatment.

Impact of serum levels and gene polymorphism of cytokines on chronic hepatitis C infection

The factors leading to clearance or persistent infection of hepatitis C virus (HCV) were not well defined, and the importance of the host immune response has been highlighted. Therefore, the impact of the serum concentration and genetic polymorphism of several cytokines on the outcome of HCV infection warrant additional study. Enzyme-linked immunosorbent assay was employed to measure serum tumor necrosis factor-alpha (TNF-alpha), interleukin (IL)-4, and IL-10 concentrations on 72 hepatitis C patients and 180 controls. Furthermore, the association between single nucleotide polymorphism (SNP) of genes of these cytokines and hepatitis C infection was evaluated by polymerase chain reaction- restriction fragment length polymorphism and statistical analysis. These analyzed SNPs of cytokines included TNF-alpha G238A, TNF-alpha G308A, IL-4 C589T, IL-10 A1082G, IL-10 T819C, and IL-10 A592C. Serum levels of TNF-mu alpha, IL-4, and IL-10 were significantly higher in hepatitis C patients than that of controls (P < 0.001). Furthermore, the distribution of TNF-alpha G308A genotypes and alleles, but not others, was statistically different between patients and controls (P < 0.05). These data suggested the distribution of polymorphism at TNF-alpha G308A may be different between normal subjects and patients with chronic infection of hepatitis C.

Immunity and protection by adoptive transfer of dendritic cells transfected with hepatitis C NS3/4A mRNA

In this study, we tested the hypothesis that adoptive transfer of dendritic cells (DCs) transfected ex vivo with mRNA encoding hepatitis C virus (HCV) NS3/4A would initiate potent HCV-specific protective immune responses in vivo. Murine DCs were transfected with NS3/4A mRNA or eGFP mRNA using either electroporation or Transmessenger Transfection Reagent and then used for adoptive transfer. Electroporation resulted in higher transfection efficiency but lower levels of eGFP and NS3/4A expression when compared to transfection with Transmessenger. The murine NS3/4A mRNA-transfected DCs were functional in T cell activation in vitro. Adoptive transfer of NS3/4A mRNA-transfected DCs resulted in migration to regional lymph nodes, strong cellular immune responses and protection from challenge with vaccinia virus expressing NS3/NS4/NS5 in mice. Furthermore, although Transmessenger mediated transfection was less efficient than electroporation in terms of number of transfected cells, the DCs transfected with NS3/4A mRNA and Transmessenger expressed higher levels of protein and induced stronger immune responses and protection than DCs transfected with NS3/4A mRNA by electroporation. Since no study has explored the in vivo efficacy of mRNA-transfected DC-mediated vaccination against viral diseases, including hepatitis C, our study provided a novel vaccination strategy against hepatitis C as well as other pathogens.

Upregulation of indoleamine 2,3-dioxygenase in hepatitis C virus infection

Indoleamine 2,3-dioxygenase (IDO) is induced by proinflammatory cytokines and by CTLA-4-expressing T cells and constitutes an important mediator of peripheral immune tolerance. In chronic hepatitis C, we found upregulation of IDO expression in the liver and an increased serum kynurenine/tryptophan ratio (a reflection of IDO activity). Huh7 cells supporting hepatitis C virus (HCV) replication expressed higher levels of IDO mRNA than noninfected cells when stimulated with gamma interferon or when cocultured with activated T cells. In infected chimpanzees, hepatic IDO expression decreased in animals that cured the infection, while it remained high in those that progressed to chronicity. For both patients and chimpanzees, hepatic expression of IDO and CTLA-4 correlated directly. Induction of IDO may dampen T-cell reactivity to viral antigens in chronic HCV infection.

Modulation of the IL-12/IFN-γ axis by IFN-α therapy for hepatitis C

Although IFN-alpha forms the foundation of therapy for chronic hepatitis C, only a minority of patients has a sustained response to IFN-alpha alone. The antiviral activities of IFN-alpha formed the rationale for its use in viral hepatitis. However, IFN-alpha and the other Type I IFNs are also pleiotropic immune regulators. Type I IFNs can promote IFN-gamma production by activating STAT4 but can also inhibit production of IL-12, a potent activator of STAT4 and IFN-gamma production. The efficacy of IFN-alpha in the treatment of hepatitis C may therefore depend in part on the balance of IFN-gamma-inducing and IL-12-suppressing effects. We characterized the effects of pegylated IFN-alpha therapy for hepatitis C on the capacity of patients' PBMC to produce IL-12 and IFN-gamma ex vivo. Cells from patients with a sustained virological response to therapy had significantly greater levels of IFN-alpha-driven IFN-gamma production prior to treatment than those from nonresponding patients. No differences in pretreatment IL-12 productive capacity were seen between patient groups. However, therapy with IFN-alpha led to suppression of inducible IL-12 production throughout the course of therapy in both groups of patients.

[New therapies for hepatitis C]

Hepatitis C virus is an important public health threat, not only because of the high prevalence of this infection in western and third world countries, but also because of the high rate of resistance to the available antiviral therapy that consists on the use of pegylated interferon plus ribavirin. Currently, new forms of therapy are being developed based on a more precise knowledge of the structure and function of the viral proteins and of the strategies used by the virus to escape the immune and interferon systems. The new therapeutic approaches aim at different objectives: a) the inhibition of viral replication by blocking the viral protease and/or replicase; b) the use of other types of interferon with more potent antiviral effect, c) the induction of a specific anti-viral immune response by means of immunomodulatory compounds or therapeutic vaccination, d) the blockade of "de novo" infection of other cells with neutralizing antibodies, e) the induction of a antiviral state in the liver by transferring to this organ the gene of interferon and/or immunostimulating cytokines.

Dendritic cells pulsed with hepatitis C virus NS3 protein induce immune responses and protection from infection with recombinant vaccinia virus expressing NS3

Infections with Hepatitis C virus (HCV) pose a serious health problem worldwide. In this study, the hypothesis that adoptive transfer of dendritic cells (DCs) pulsed with HCV NS3 protein and matured with an oligodeoxynucleotide (ODN) containing CpG motifs (CpG) ex vivo would initiate potent HCV-specific protective immune responses in vivo was tested. NS3 protein was efficiently transduced into DCs and treatment of DCs with CpG ODN induced phenotypic maturation and specifically increased the expression of CD40. DCs matured with CpG ODN produced higher interleukin 12 levels and a stronger allogeneic T-cell response compared with untreated DCs. Notably, there were no differences between NS3-pulsed DCs and DCs pulsed with a control protein with respect to phenotype, cytokine production or mixed lymphocyte reaction, indicating that transduction with NS3 protein did not impair DC functions. Compared with the untreated NS3-pulsed DCs, the NS3-pulsed DCs matured with CpG ODN induced stronger cellular immune responses including enhanced cytotoxicity, higher interferon-gamma production and stronger lymphocyte proliferation. Upon challenge with a recombinant vaccinia virus expressing NS3, all mice immunized with NS3-pulsed DCs showed a significant reduction in vaccinia virus titres when compared with mock-immunized mice. However, the NS3-pulsed DCs matured with CpG ODN induced higher levels of protection compared with the untreated NS3-pulsed DCs. These data are the first to show that NS3-pulsed DCs induce specific immune responses and provide protection from viral challenge, and also demonstrate that CpG ODNs, which have a proven safety profile, would be useful in the development of DC vaccines.

Activation of Refractory T Cell Responses against Hepatitis C Virus Core Protein by Ablation of Interfering Hydrophobic Domains

Hepatitis C virus (HCV) is the major pathogen of chronic hepatitis and liver disease, but currently there are no prophylactic HCV vaccines available. The HCV core protein-encoding sequence is among the most conserved genes in the HCV genome, making it a prime candidate for a component of a vaccine. The core protein localizes to the endoplasmic reticulum (ER) through a C-terminal hydrophobic region that is cotranslationally inserted into the ER membrane. Here we show that removal of the C-terminal hydrophobic region confers nuclear localization and enhances proteasomal degradation of the core protein in mammalian cells. This efficient protein proteolysis induces enhanced core-specific CD8(+) T cell responses in BALB/c mice immunized with plasmids expressing C-terminal deletions of the HCV core protein. These results suggest that more potent HCV vaccines can be achieved by targeting the core protein for proteasomal degradation by deletion of its C-terminal hydrophobic domain.

Characterization of T-cell responses against immunodominant epitopes from hepatitis C virus E2 and NS4a proteins

Successful clearance of hepatitis C virus (HCV) infection has been associated with strong cellular immune responses against viral antigens. However, although the magnitude of these responses is clearly important for viral eradication, more studies are needed to unravel the fine specificity of the protective anti-HCV immunity in infected patients. This was the aim of the present study. Overlapping peptides spanning the sequence of HCV E2 and NS4a proteins were used to stimulate T cells from patients with chronic hepatitis C divided into three groups: naïve patients, patients who exhibited sustained response to interferon (IFN)-alpha therapy and patients who failed to respond to the treatment. Interleukin-2 production by stimulated cells was measured in each case. Patients with sustained response to therapy had stronger responses to E2 peptides than nonresponders, whereas naïve patients demonstrated intermediate reactivity. In the case of NS4a, responses against peptides where similar in all groups of patients. Analysis of the peptides recognized by T cells showed that responses were broad and heterogeneous, and some immunodominant epitopes, preferentially recognized by patients exhibiting sustained response to treatment, were found. These results confirm the role of cellular immune responses in viral clearance, and stress the importance of immunodominant regions within HCV antigens. These viral sequences may represent valuable immunogens for preparation of therapeutic or prophylactic vaccines.

Hepatitis C virus core protein: an update on its molecular biology, cellular functions and clinical implications

The present review article is an update on various features of hepatitis C virus (HCV) core protein including its molecular biology, role in HCV replication, involvement in HCV pathogenesis, etiological role in hepatocellular carcinogenesis, significance in diagnosis and vaccination against HCV infection. Core protein is a structural protein of HCV virus and has only recently been characterized. It was found to play a major role in HCV-induced viral hepatitis. Although published information shows a lot about the clinical significance of HCV core protein, several studies are still needed to demonstrate its exact significance in viral biology and underlying HCV pathogenesis.

Enhancement of CD4 and CD8 immunity by anti-CD137 (4-1BB) monoclonal antibodies during hepatitis C vaccination with recombinant adenovirus

The induction of protective or therapeutic cellular immunity against hepatitis C virus (HCV) is a difficult goal. In a previous work we showed that immunization with a recombinant adenovirus encoding HCV-NS3 (RAdNS3) could partially protect mice from challenge with a vaccinia virus encoding HCV antigens. We sought to investigate whether systemic administration of an immunostimulatory monoclonal antibody directed against the lymphocyte surface molecule CD137 could enhance the immunity elicited by RAdNS3. It was found that treatment with anti-CD137 mAb after the administration of a suboptimal dose of RAdNS3 enhanced cytotoxic and T helper cell responses against HCV NS3. Importantly, the ability of RAdNS3 to induce protective immunity against challenge with a recombinant vaccinia virus expressing HCV proteins was markedly augmented. Thus, combination of immunostimulatory anti-CD137 mAb with recombinant adenoviruses expressing HCV proteins might be useful in strategies of immunization against HCV.

Prospects for dendritic cell vaccination in persistent infection with hepatitis C virus

Although hepatitis C virus (HCV) is classified in the Hepacivirus genus in the family Flaviviridae, it is unlike most of the other members of this family due to its propensity to cause persistent infections. This persistent infection eventually results in chronic liver disease, cirrhosis and hepatocellular carcinoma in a proportion of infected individuals. It has been difficult to examine correlates of clearance or persistence because most acute phase HCV infections are subclinical or result in symptoms which are non-specific; consequently, acute infections are not generally recognised and patients often present many years later with persistent infection and accompanying chronic liver disease. Nevertheless, seminal studies, performed during the acute phase, have identified a number of factors which are likely to influence the outcome of infection, although it is possible that the mechanism is multifactorial. One of these factors is impairment of dendritic cell function by a mechanism resulting from expression of an HCV protein(s) in these cells. This may be a major factor in the failure of the immune response to expand after HCV infection, leading to persistence. Nevertheless, it may be possible to overcome this defect by autologous transfusion of HCV antigen-loaded, mature dendritic cells and the purpose of this review is to highlight the need and general approaches for developing dendritic cell-based immunotherapy for HCV infection.

Hepatitis C virus-specific cytolytic T cell responses after antiviral therapy

Antigen-specific T cells are likely to provide a critical defense against hepatitis C virus (HCV) infection. However, their detection in blood is uncommon except in persons who undergo spontaneous recovery after acute HCV infection. We postulated that virological responses after antiviral interferon-alpha therapy may be associated with enhanced cytolytic T cell immunity. Peripheral blood memory CTL responses were quantified using short term limiting dilution culture, with cytolytic function detected by standard chromium release assay. In this cross-sectional study, 5 of 11 interferon-alpha or interferon-alpha plus ribavirin-treated subjects exhibited cytolytic T cell responses after therapy completion; 4 of these 5 subjects were HCV RNA negative at the time of assay. In contrast, only 1 of 9 untreated chronically viremic subjects had detectable HCV-specific cytolytic T cell responses. Although the requisite factors necessary to achieve sustained virologic response after therapy remain largely undefined, the findings presented here suggest that antiviral therapy-induced virological clearance may be associated with the induction, expansion, and/or recirculation of HCV antigen-specific cytolytic T cells, and may play a role in the maintenance of a nonviremic state.

Hepatitis C virus structural proteins impair dendritic cell maturation and inhibit in vivo induction of cellular immune responses

Hepatitis C virus (HCV) chronic infection is characterized by low or undetectable cellular immune responses against HCV antigens. Some studies have suggested that HCV proteins manipulate the immune system by suppressing the specific antiviral T-cell immunity. We have previously reported that the expression of HCV core and E1 proteins (CE1) in dendritic cells (DC) impairs their ability to prime T cells in vitro. We show here that immunization of mice with immature DC transduced with an adenovirus encoding HCV core and E1 antigens (AdCE1) induced lower CD4(+)- and CD8(+)-T-cell responses than immunization with DC transduced with an adenovirus encoding NS3 (AdNS3). However, no differences in the strength of the immune response were detected when animals were immunized with mature DC subsequently transduced with AdCE1 or AdNS3. According to these findings, we observed that the expression of CE1 in DC inhibited the maturation caused by tumor necrosis factor alpha or CD40L but not that induced by lipopolysaccharide. Blockade of DC maturation by CE1 was manifested by a lower expression of maturation surface markers and was associated with a reduced ability of AdCE1-transduced DC to activate CD4(+)- and CD8(+)-T-cell responses in vivo. Our results suggest that HCV CE1 proteins modulate T-cell responses by decreasing the stimulatory ability of DC in vivo via inhibition of their physiological maturation pathways. These findings are relevant for the design of therapeutic vaccination strategies in HCV-infected patients.

Long-term interleukin 10 therapy in chronic hepatitis C patients has a proviral and anti-inflammatory effect

An imbalance in Th1 and Th2 cytokine production is implicated in disease progression of HCV. Our aim was to determine the effect of IL-10 administration in patients with HCV-related liver disease. Thirty patients with advanced fibrosis who had failed antiviral therapy were enrolled in a 12-month treatment regimen with SQ IL-10 given daily or thrice weekly. Liver biopsies were performed before and after therapy. Serum and PBMC were collected for HCV RNA, ALT, and functional T-cell analysis. IL-10 led to significant improvement in serum ALT (mean ALT: day 0 = 142 +/- 17 vs. month 12 = 75 +/- 10; P <.05). Hepatic inflammation score decreased by at least 2 in 13 of 28 patients (mean decrease from 4.6 +/- 0.3 to 3.7 +/- 0.3, P <.05) and 11 of 28 showed a reduction in fibrosis score (mean change from 5.0 +/- 0.2 to 4.5 +/- 0.3, P <.05). Serum HCV RNA levels increased by 0.5 log during therapy (mean HCV RNA day 0: 12.3 +/- 3.0 Meq/mL; 12 months: 38 Meq/mL; P <.05) and returned to baseline at the end of follow-up (11.0 +/- 2.4 Meq/mL). Five patients developed viral loads of greater than 120 Meq/mL and two of these developed an acute flare in serum ALT. IL-10 caused a decrease in the number of HCV-specific CD4+ and CD8+ IFN-gamma secreting T cells and alterations in PBMC cytokine production towards a Th2 dominant profile. These changes parallel the improvement in ALT and rise in HCV RNA. In conclusion, long-term rIL-10 therapy appears to decrease disease activity, but also leads to increased HCV viral burden via alterations in immunologic viral surveillance.

Pleiotropic mechanisms of ribavirin antiviral activities

Renewed interest in the mechanism of action of ribavirin results from its synergistic enhancement of interferon therapy and the need to develop more efficacious agents to treat hepatitis C virus infection. Since the discovery of ribavirin over 30 years ago by scientists at ICN Pharmaceuticals, many mechanisms of action for ribavirin have been proposed. These include inhibition of host inosine monophosphate dehydrogenase by ribavirin monophosphate, inhibition of viral capping enzymes, inhibition of viral RNA synthesis by ribavirin triphosphate, lethal mutagenesis of viral RNA genomes resulting from promiscuous incorporation of ribavirin triphosphate by the viral RNA polymerase, and modulation of the host immune responses. In this article, we will briefly review the evidence for these mechanisms, emphasizing recent findings. In addition, we will discuss strategies for development of nucleoside analogs that may replace ribavirin in the future.

Vaccination with an adenoviral vector encoding hepatitis C virus (HCV) NS3 protein protects against infection with HCV-recombinant vaccinia virus

Cellular immune response plays an important role in the clearance of hepatitis C virus (HCV). Thus, development of efficient ways to induce anti-viral cellular immune responses is an important step toward prevention and/or treatment of HCV infection. With this aim, we have constructed a replication-deficient recombinant adenovirus expressing HCV NS3 protein (RAdNS3). The efficacy of RAdNS3 was tested in vivo by measuring the protection against infection with a recombinant vaccinia virus expressing HCV-polyprotein (vHCV1-3011). Immunisation with 10(9)pfu of RAdNS3 induced anti-NS3 humoral, T helper and T cytotoxic responses. We identified eight epitopes recognised by IFN-gamma producing cells, five of them exhibiting lytic activity. Moreover, we show that RAdNS3 immunised mice were protected against challenge with vHCV1-3011 and that this protection was mediated by CD8(+) cells. In conclusion, our results suggest that adenoviral vectors encoding NS3 might be useful for the induction of prophylactic and/or therapeutic anti-HCV immunity.

Southeast Asian patients with chronic hepatitis C: the impact of novel genotypes and race on treatment outcome

Hepatitis C virus (HCV) genotype and other host and viral factors influence treatment outcome in chronic HCV infection. We evaluated the effect of race and genotype on interferon and ribavirin treatment outcome in 70 Southeast Asian (SEA) and 50 white patients. Genotype was based on the 5' untranslated region (5'UTR) with a commonly used line probe assay (INNO-LiPA HCV II) that may mistype genotype 7, 8, or 9 as 1b. HCV core region sequencing resulted in reclassification of 8 genotype 1 and 25 genotype 1b SEA subjects as genotype 7, 8, or 9. Twenty-six SEA genotype 7, 8, and 9 (79%) and 10 SEA true genotype 1b (59%) patients achieved a sustained virologic response (SVR) compared with 15 (34%) white genotype 1b patients. Logistic regression analysis showed that SEA patients with genotype 7, 8, or 9 were more likely to achieve a SVR than white genotype 1b patients (OR 16.56; 95%CI 4.16, 65.91) as were SEA true genotype 1b patients compared with white genotype 1b patients (OR 4.63; 95%CI 1.19, 18.04). In conclusion, a proportion of SEA patients classified by INNO-LiPA as genotype 1b were in reality genotype 7, 8, or 9. In comparison with white genotype 1b patients, both SEA genotype 1b and SEA genotype 7, 8, and 9 patients showed a significantly greater SVR. HCV core sequencing was necessary to determine genotype accurately in persons potentially exposed to HCV genotypes 7, 8, or 9. This study also supports the concept that race and ethnicity are important determinants of treatment outcome in HCV infected patients.

Abnormal priming of CD4(+) T cells by dendritic cells expressing hepatitis C virus core and E1 proteins

Patients infected with hepatitis C virus (HCV) have an impaired response against HCV antigens while keeping immune competence for other antigens. We hypothesized that expression of HCV proteins in infected dendritic cells (DC) might impair their antigen-presenting function, leading to a defective anti-HCV T-cell immunity. To test this hypothesis, DC from normal donors were transduced with an adenovirus coding for HCV core and E1 proteins and these cells (DC-CE1) were used to stimulate T lymphocytes. DC-CE1 were poor stimulators of allogeneic reactions and of autologous primary and secondary proliferative responses. Autologous T cells stimulated with DC-CE1 exhibited a pattern of incomplete activation characterized by enhanced CD25 expression but reduced interleukin 2 production. The same pattern of incomplete lymphocyte activation was observed in CD4(+) T cells responding to HCV core in patients with chronic HCV infection. However, CD4(+) response to HCV core was normal in patients who cleared HCV after alpha interferon therapy. Moreover, a normal CD4(+) response to tetanus toxoid was found in both chronic HCV carriers and patients who had eliminated the infection. Our results suggest that expression of HCV structural antigens in infected DC disturbs their antigen-presenting function, leading to incomplete activation of anti-HCV-specific T cells and chronicity of infection. However, presentation of unrelated antigens by noninfected DC would allow normal T-cell immunity to other pathogens.

Intrahepatic and circulating HLA class II-restricted, hepatitis C virus-specific T cells: functional characterization in patients with chronic hepatitis C

To compare the functional features of circulating and intrahepatic hepatitis C virus (HCV)-specific CD4+ T cells in chronic HCV infection, peripheral blood and liver-infiltrating lymphocytes from 29 patients with chronic hepatitis C were stimulated with structural and nonstructural HCV proteins to produce antigen-specific T-cell lines and clones. Antigen specificity, fine specificity, phenotype, cytokine production, and T-cell receptor (TCR)-vbeta chain expression were analyzed. The results indicate a hierarchy of stimulatory capacity by the different HCV proteins, core being the antigen most frequently recognized by CD4+ intrahepatic lymphocytes, followed by NS4 and NS5. The CD4 response was directed simultaneously against different HCV proteins in individual patients, but fine-specificity analysis indicated that the response was generally focused on a limited number of immunodominant epitopes. Although the narrowly focused nature of this response may favor the emergence of escape mutations, this event was not observed by following-up over time the sequence of 2 epitopes strongly immunodominant for intrahepatic CD4 cells of a patient with chronic HCV infection. In conclusion, simultaneous analysis of peripheral blood and intrahepatic CD4 cells in the same patients indicated a predominant Th1 profile of HCV-specific CD4 cells and suggests a specific compartmentalization of virus-specific T cells into the liver.

Thyroid dysfunction during treatment of chronic hepatitis C with interferon alpha: no association with either interferon dosage or efficacy of therapy

OBJECTIVES

Treatment of chronic hepatitis C with interferon-alpha (IFN-alpha) may induce thyroid disorders. We evaluated whether this risk is related to the dosage of IFN-alpha or the virological treatment response. Other possible risk factors as well as the evolution of the thyroid abnormalities were also studied.

METHODS

In this prospective trial (n=254), thyroid-stimulating hormone (TSH), free thyroxin (fT4) and thyroid peroxidase autoantibodies were measured before, during and after treatment for hepatitis C virus (HCV). The patients were randomized to either induction therapy [IFN-alpha 6 million units (MIU) daily for 4 weeks and 3 MIU 3/7 days for 22 weeks] or conventional therapy [IFN-alpha 3 MIU 3/7 days for 26 weeks]. In addition, all patients received ribavirin (1000 or 1200 mg) daily. Sustained virological response was defined as loss of detectable HCV RNA at 6 months follow-up. Thyroid dysfunction was defined as TSH level below or above the normal range (0.2-4.5 MIU L-1).

RESULTS

Biochemical thyroid dysfunction developed in 30 (11.8%) of 254 patients. Hypothyroidism (TSH > 4.5 MIU L-1) was seen in 20 and hyperthyroidism (TSH < 0.2 MIU L-1) in 10 patients. Nine of the 30 patients developed symptomatic thyroid disease and HCV treatment was discontinued because of thyroid dysfunction in three of these patients. Thyroid dysfunction occurred in 15 (11.7%) of 128 patients who received high-dose IFN-alpha induction therapy as compared with 15 (11.9%) of 126 patients who received conventional IFN-alpha therapy (P=0.96). Amongst 231 patients who completed all 6 months of HCV treatment, a sustained virological response was obtained in 19 (66%) of 29 with thyroid dysfunction and 109 (54%) of 202 without (P=0.24). By multivariate analysis female gender and Asian origin were independent predictors of developing biochemical thyroid dysfunction (P < 0.01).

CONCLUSION

Thyroid dysfunction occurred in 11.8% of patients treated for chronic hepatitis C with IFN-alpha and ribavirin. Neither the IFN-alpha dosage nor the virological response to treatment were related to the incidence of thyroid dysfunction.

Immunopathogenesis of hepatitis C virus infection

Hepatitis C virus, a recently identified member of the family Flaviviridae, is an important cause of chronic viral hepatitis and cirrhosis. There are similarities in the nature of the immune response to this pathogen with immunity in other flavivirus and hepatotropic virus infections, such as hepatitis B. However, the high rate of viral persistence after primary hepatitis C infection, and the observation that neutralizing antibodies are not protective, would suggest that there are a number of important differences between hepatitis C, other flaviviruses, and hepatitis B. The phenomenon of quasispecies evolution and other viral factors have been proposed to contribute to immune evasion by hepatitis C virus. In the face of established persistent infection, virus-specific cytotoxic T lymphocytes may exert some control over viral replication. However, these same effectors may also be responsible for the progressive liver damage characteristic of chronic hepatitis C infection. The nature of protective immunity, including the role of innate immune responses early after hepatitis C exposure, remains to be defined.

The immunopathogenesis of hepatitis C virus infection

The outcome of HCV infection is determined by the interaction between the virus and the host immune system. The persistence of infection in most HCV-infected individuals, despite the presence of HCV-directed antibodies, suggests that such antibodies fail to induce viral clearance. Patients with self-limited hepatitis C have evidence of a polyclonal, multispecific CD8+ T-cell response along with a coordinated CD4+ T-cell response that is associated with eradication of HCV infection. Cytokines are produced both locally within the liver and systemically and may play an important role in controlling viral replication and contributing to hepatocellular damage through amplification of a nonspecific immune response. In most patients, the humoral, cellular immune, and cytokine response seem insufficient to eradicate infection. In its attempt to clear the virus from the liver, the immune system contributes to the hepatocellular injury seem in most chronically infected patients. A better understanding of the host's immune response may provide further insight on the pathogenetic mechanisms involved in development of chronic hepatitis and aid the development of better therapeutic strategies.

Mechanisms of action of ribavirin in antiviral therapies

Although ribavirin was originally synthesized over 30 years ago and has been used to treat viral infections as monotherapy (respiratory syncytial virus and Lassa fever virus) or with interferon-alpha (IFN-alpha) as combination therapy (hepatitis C virus), the precise mechanism of its therapeutic activities remains controversial. In this review we focus on two main biological properties of ribavirin: its indirect and direct antiviral activities (with particular emphasis on its efficacy against chronic hepatitis C infection). Each property could individually or collectively account for its clinical efficacy against viral infections. First, with emphasis on the evidence for indirect activities of ribavirin, we will review the clinical observations that suggest that the immunomodulatory properties of ribavirin can in part account for its antiviral activities in vivo. We will then describe the mode of ribavirin's direct antiviral activities. These direct activities can be ascribed to several possible mechanisms, including the recently described activity as an RNA mutagen, a property that may be important in driving a rapidly mutating RNA virus over the threshold to 'error catastrophe'.