Immune responses in hepatitis C virus infection and mechanisms of hepatitis C virus persistence

Hepatitis C Virus Infection Cycle-Specific MicroRNA Profiling Reveals Stage-Specific miR-4423-3p Targets RIG-I to Facilitate Infection

Hepatitis C virus (HCV) infection is one of the main causes of chronic liver diseases, the disorders of which involve multiple pathological processes and elements including host factors such as non-coding small RNAs. Although several genes have been reported to be correlated with HCV infection, the potential regulatory network has not been deciphered clearly. By small RNA sequencing, we clarified the expression profile of microRNAs (miRNAs) in HCV-infected Huh7 and Huh7.5.1 cells and identified 6 dysregulated miRNAs with the same expression trend and 32 dysregulated miRNAs with different expression trends during different stages of HCV life cycle. By looking into each infection stage, we found that 6 miRNAs were entry stage specific, 4 miRNAs were replication stage specific, and 1 miRNA was related to the transmission stage. Moreover, due to the fact that Huh7.5.1 cells have a retinoic acid-inducible gene 1 (RIG-I) mutation which causes reduced production of interferons (IFNs), we here focused on the miRNAs of different trends to decipher the RIG-I/IFN specific miRNAs. Among them, miR-4423-3p showed a significant promotive effect on HCV infection by suppressing RIG-I/IFN pathway through direct binding to RIG-I mRNA. Together, the results displayed novel insights into the miRNA regulatory networks in HCV infection and progression, thus providing a prosperous perspective into the establishment of novel therapeutic and diagnostic targets of the disease.

Ledipasvir/Sofosbuvir for Patients Coinfected With Chronic Hepatitis C and Hepatitis B in Taiwan: Follow-up at 108 Weeks Posttreatment

BACKGROUND

For patients coinfected with hepatitis C virus (HCV) and hepatitis B virus (HBV), HCV treatment with direct-acting antivirals can lead to HBV reactivation. We evaluated HBV reactivation during ledipasvir/sofosbuvir treatment and 108-week follow-up.

METHODS

In Taiwan, 111 patients with HCV genotype 1 or 2 and HBV received ledipasvir/sofosbuvir (90mg/400mg) once daily for 12 weeks. HBV virologic reactivation was defined as postbaseline increase in HBV DNA from either less than the lower limit of quantification (LLOQ, 20 IU/mL) to equal to or more than LLOQ or equal to or more than LLOQ to >1 log10 IU/mL. HBV clinical reactivation was HBV virologic reactivation with alanine aminotransferase (ALT) >2× upper limit of normal. Factors associated with development of HBV virologic or clinical reactivation were evaluated with logistic regression analysis.

RESULTS

All patients (100%, 111/111) maintained HCV suppression through 108 weeks after treatment. HBV virologic reactivation occurred in 73% of patients (81/111). Clinical reactivation occurred in 9% (10/111). The majority of HBV virologic reactivations (86%, 70/81) occurred by follow-up week 12, whereas clinical reactivation was generally more delayed. Eight (7%, 8/111) initiated HBV therapy. In regression analyses, baseline HBV DNA and hepatitis B surface antigen (HBsAg) levels were associated with HBV virologic reactivation and baseline ALT and HBV DNA, and HBsAg levels were associated with HBV clinical reactivation.

CONCLUSION

Among HCV/HBV coinfected patients treated with direct-acting antivirals for HCV, HBV virologic reactivation occurred in a majority of patients during treatment and follow-up. In most patients, HBV virologic reactivation was asymptomatic; only a small proportion initiated HBV treatment. Notably, clinical reactivation may still occur >3 months after end of therapy.

CLINICAL TRIALS REGISTRATION

NCT02613871.

Hepatitis C Virus Infection: Host⁻Virus Interaction and Mechanisms of Viral Persistence

Hepatitis C (HCV) is a major cause of liver disease, in which a third of individuals with chronic HCV infections may develop liver cirrhosis. In a chronic HCV infection, host immune factors along with the actions of HCV proteins that promote viral persistence and dysregulation of the immune system have an impact on immunopathogenesis of HCV-induced hepatitis. The genome of HCV encodes a single polyprotein, which is translated and processed into structural and nonstructural proteins. These HCV proteins are the target of the innate and adaptive immune system of the host. Retinoic acid-inducible gene-I (RIG-I)-like receptors and Toll-like receptors are the main pattern recognition receptors that recognize HCV pathogen-associated molecular patterns. This interaction results in a downstream cascade that generates antiviral cytokines including interferons. The cytolysis of HCV-infected hepatocytes is mediated by perforin and granzyme B secreted by cytotoxic T lymphocyte (CTL) and natural killer (NK) cells, whereas noncytolytic HCV clearance is mediated by interferon gamma (IFN-γ) secreted by CTL and NK cells. A host-HCV interaction determines whether the acute phase of an HCV infection will undergo complete resolution or progress to the development of viral persistence with a consequential progression to chronic HCV infection. Furthermore, these host-HCV interactions could pose a challenge to developing an HCV vaccine. This review will focus on the role of the innate and adaptive immunity in HCV infection, the failure of the immune response to clear an HCV infection, and the factors that promote viral persistence.

Dominating expression of negative regulatory factors downmodulates major histocompatibility complex Class-II expression on dendritic cells in chronic hepatitis C infection

AIM

To elucidate the molecular mechanisms leading to development of functionally impaired dendritic cells (DCs) in chronic hepatitis C (CHC) patients infected with genotype 3 virus.

METHODS

This prospective study was conducted on the cohorts of CHC individuals identified as responders or non-responders to antiviral therapy. Myeloid DCs were isolated from the peripheral blood of each subject using CD1c (BDCA1)(+) DC isolation Kit. Monocytes from healthy donor were cultured with DC growth factors such as IL-4 and GM-CSF either in the presence or absence of hepatitis C virus (HCV) viral proteins followed by LPS stimulation. Phenotyping was done by flowcytometry and gene expression profiling was evaluated by real-time PCR.

RESULTS

Non-responders [sustained virological response (SVR)-ve] to conventional antiviral therapy had significantly higher expression of genes associated with interferon responsive element such as IDO1 and PD-L1 (6-fold) and negative regulators of JAK-STAT pathway such as SOCS (6-fold) as compared to responders (SVR+ve) to antiviral therapy. The down-regulated genes in non-responders included factors involved in antigen processing and presentation mainly belonging to major histocompatibility complex (MHC) Class-II family as HLA-DP, HLA-DQ (2-fold) and superoxide dismutase (2-fold). Cells grown in the presence of HCV viral proteins had genes down-regulated for factors involved in innate response, interferon signaling, DC maturation and co-stimulatory signaling to T-cells, while the genes for cytokine signaling and Toll-like receptors (4-fold) were up-regulated as compared to cells grown in absence of viral proteins.

CONCLUSION

Underexpressed MHC class-II genes and upregulated negative regulators in non-responders indicate diminished capacity to present antigen and may constitute mechanism of functionally defective state of DCs.

Serum Cytokine of IL-10 and IL-12 in Chronic Liver Disease: The Immune and Inflammatory Response

The current study was designed to investigate the potential association of serum interleukin-10 and interleukin-12 with HCV infection in chronic liver disease and to evaluate their possible role as new biomarkers in HCC development. Material and Methods. Forty-one patients suffering from chronic liver disease (33 patients harbor HCV infection and 8 are HCV-negative patients) were enrolled in the present study and histopathologically diagnosed into 15 patients with HCC, 16 patients with LC, and 10 patients with liver histology compatible with precirrhotic hepatitis (PCH). Ten patients complaining of cholecystitis were included as nondisease control. Serum levels of IL-10 and IL-12 were measured by enzyme linked immunosorbent assay (ELISA). Results. HCV-infected patients showed elevated expression of IL-10 and IL-12 compared to nondisease controls (P < 0.0001) but there is no significant difference with respect to their expression in HCV-negative patients. Serum IL-10 and IL-12 were elevated significantly with disease progression (P < 0.0001) and a positive correlation coefficient was detected between IL-10, IL-12 (r = 0.785, P < 0.0001), and transaminase values suggesting their possible role in chronic inflammation progression leading to HCC. Conclusion. IL-10 and IL-12 might be involved in chronic inflammation progression leading to HCC and their evaluation could be used as new biomarkers to reflect the degree of inflammation in HCC development.

Comparative Immunogenicity in Rabbits of the Polypeptides Encoded by the 5' Terminus of Hepatitis C Virus RNA

Recent studies on the primate protection from HCV infection stressed the importance of immune response against structural viral proteins. Strong immune response against nucleocapsid (core) protein was difficult to achieve, requesting further experimentation in large animals. Here, we analyzed the immunogenicity of core aa 1–173, 1–152, and 147–191 and of its main alternative reading frame product F-protein in rabbits. Core aa 147–191 was synthesized; other polypeptides were obtained by expression in E. coli. Rabbits were immunized by polypeptide primes followed by multiple boosts and screened for specific anti-protein and anti-peptide antibodies. Antibody titers to core aa 147–191 reached 10⁵; core aa 1–152, 5 × 10⁵; core aa 1–173 and F-protein, 10⁶. Strong immunogenicity of the last two proteins indicated that they may compete for the induction of immune response. The C-terminally truncated core was also weakly immunogenic on the T-cell level. To enhance core-specific cellular response, we immunized rabbits with the core aa 1–152 gene forbidding F-protein formation. Repeated DNA immunization induced a weak antibody and sustained proliferative response of broad specificity confirming a gain of cellular immunogenicity. Epitopes recognized in rabbits overlapped those in HCV infection. Our data promotes the use of rabbits for the immunogenicity tests of prototype HCV vaccines.

IL-26 is overexpressed in chronically HCV-infected patients and enhances TRAIL-mediated cytotoxicity and interferon production by human NK cells

OBJECTIVE

Interleukin-26 (IL-26) is a member of the IL-10 cytokine family, first discovered based on its peculiar expression by virus-transformed T cells. IL-26 is overexpressed in chronic inflammation (rheumatoid arthritis and Crohn's disease) and induces proinflammatory cytokines by myeloid cells and some epithelial cells. We thus investigated the expression and potential role of IL-26 in chronic HCV infection, a pathology associated with chronic inflammation.

DESIGN

IL-26 was quantified in a cohort of chronically HCV-infected patients, naive of treatment and its expression in the liver biopsies investigated by immunohistochemistry. We also analysed the ability of IL-26 to modulate the activity of natural killer (NK) cells, which control HCV infection.

RESULTS

The serum levels of IL-26 are enhanced in chronically HCV-infected patients, mainly in those with severe liver inflammation. Immunohistochemistry reveals an intense IL-26 staining in liver lesions, mainly in infiltrating CD3+ cells. We also show that NK cells from healthy subjects and from HCV-infected patients are sensitive to IL-26. IL-26 upregulates membrane tumour necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL) expression on CD16- CD56(bright) NK cells, enabling them to kill HCV-infected hepatoma cells, with the same efficacy as interferon (IFN)-α-treated NK cells. IL-26 also induces the expression of the antiviral cytokines IFN-β and IFN-γ, and of the proinflammatory cytokines IL-1β and TNF-α by NK cells.

CONCLUSIONS

This study highlights IL-26 as a new player in the inflammatory and antiviral immune responses associated with chronic HCV infection.

New Insights into IDO Biology in Bacterial and Viral Infections

Initially, indoleamine-2,3-dioxygenase (IDO) has been introduced as a bactericidal effector mechanism and has been linked to T-cell immunosuppression and tolerance. In recent years, evidence has been accumulated that IDO also plays an important role during viral infections including HIV, influenza, and hepatitis B and C. Moreover, novel aspects about the role of IDO in bacterial infections and sepsis have been revealed. Here, we review these recent findings highlighting the central role of IDO and tryptophan metabolism in many major human infections. Moreover, we also shed light on issues concerning human-specific and mouse-specific host–pathogen interactions that need to be considered when studying the biology of IDO in the context of infections.

CD4+ primary T cells expressing HCV-core protein upregulate Foxp3 and IL-10, suppressing CD4 and CD8 T cells

Adaptive T cell responses are critical for controlling HCV infection. While there is clinical evidence of a relevant role for regulatory T cells in chronic HCV-infected patients, based on their increased number and function; mechanisms underlying such a phenomena are still poorly understood. Accumulating evidence suggests that proteins from Hepatitis C virus can suppress host immune responses. We and others have shown that HCV is present in CD4+ lymphocytes from chronically infected patients and that HCV-core protein induces a state of unresponsiveness in the CD4+ tumor cell line Jurkat. Here we show that CD4+ primary T cells lentivirally transduced with HCV-core, not only acquire an anergic phenotype but also inhibit IL-2 production and proliferation of bystander CD4+ or CD8+ T cells in response to anti-CD3 plus anti-CD28 stimulation. Core-transduced CD4+ T cells show a phenotype characterized by an increased basal secretion of the regulatory cytokine IL-10, a decreased IFN-γ production upon stimulation, as well as expression of regulatory T cell markers, CTLA-4, and Foxp3. A significant induction of CD4+CD25+CD127(low)PD-1(high)TIM-3(high) regulatory T cells with an exhausted phenotype was also observed. Moreover, CCR7 expression decreased in HCV-core expressing CD4+ T cells explaining their sequestration in inflamed tissues such as the infected liver. This work provides a new perspective on de novo generation of regulatory CD4+ T cells in the periphery, induced by the expression of a single viral protein.

Granulocyte-macrophage colony-stimulating factor genetic adjuvant enhances the immune stimulatory effects of plasmid DNA encoding the hepatitis C virus core protein

AIM: To study the effect of granulocyte-macrophage colony-stimulating factor (GM-CSF) genetic adjuvant on immune response induced by plasmid DNA encoding the hepatitis C virus (HCV) core (C) protein.

METHODS: The gene encoding the HCV C protein was amplified by PCR from HCV 1b genotype and inserted into the pUC119 vector. The HCV C gene was then subcloned into the pCMH6K eukaryotic vector, and the resulting plasmid was named pCMH6K/HCV-C. The recombinant vector was confirmed by restriction enzyme analysis and DNA sequencing, and transfected into China hamster ovary (CHO) cells with Lipofectamine 2000. Distribution of the HCV C protein in transfected CHO cells was detected by immunofluorescence. Balb/c mice were vaccinated with the recombinant plasmid with or without the GM-CSF gene. HCV C-specific antibody in serum was measured by ELISA. The changes in T lymphocyte subsets and levels of Th cell intracellular cytokines interferon-γ (IFN-γ) and interleukin-4 (IL-4) in splenic cell suspension from immunized mice were evaluated by flow cytometric analysis. CTL activity was assessed by LDH assay.

RESULTS: Restrict enzyme digestion and DNA sequencing indicated that the recombinant pCMH6K/HCV-C was successfully constructed. The expression of plasmid-encoded protein was mainly distributed in membrane and scarcely in cytoplasm of transfected CHO cells. The percentage of CD4⁺ T cells in spleen cells in the pCMH6K/HCV-C+pGM-CSF co-vaccination group was significantly higher than those in other groups (all P < 0.05). The percentage of CD8⁺ T cells showed no significant differences among each group (P > 0.05). CTL activity induced by GM-CSF DNA co-vaccination was significantly higher than that immunized with the same amount of other naked DNA (P < 0.05). The ratio of IFN-γ to IL-4 in spleen cells from GM-CSF DNA co-vaccination group was significantly higher than those in other groups (all P < 0.05).

CONCLUSION: GM-CSF DNA could enhance the immune stimulatory effects of HCV DNA vaccine and induce Th1-type immune response.

Genetic polymorphism in cyclooxygenase-2 promoter affects hepatic inflammation and fibrosis in patients with chronic hepatitis C

Cyclooxygenase (COX)-2 is involved in inflammation, anti-apoptosis and carcinogenesis. The -1195GG genotype of single nucleotide polymorphism (SNP) in COX-2 promoter was associated with low platelet counts in patients with chronic hepatitis C. Polymorphism of patatin-like phospholipase domain-containing protein 3 (PNPLA3) gene (rs738409 C>G) have been reported to be associated with cirrhosis, and the major genotype of SNPs near interleukin (IL)28B are related to viral clearance. The present study was designed to assess the contribution of these SNPs to disease progression in patients with chronic hepatitis C. The study enrolled 220 Japanese patients with chronic hepatitis C. Three SNPs, -1195 COX-2, PNPLA3 and IL28B (rs8099917), were genotyped in order to analyze their association with hepatic fibrosis and inflammation. The -1195GG genotype in COX-2 was associated with advanced fibrosis and higher levels of inflammation in the liver tissues. The major genotype of IL28B was also associated with advanced fibrosis, but the polymorphism of PNPLA3 was neither associated with fibrosis nor inflammation. Multivariate analysis showed that -1195GG in COX-2 is an independent factor associated with advanced fibrosis, while the major genotype of IL28B and HCV genotype 2 were other independent factors. In conclusion, the -1195GG genotype in COX-2 is a genetic marker for liver disease progression, while the PNPLA3 genotypes are not associated with disease progression in Japanese patients with chronic hepatitis C.

Proteomic analysis of hepatitis C virus (HCV) core protein transfection and host regulator PA28γ knockout in HCV pathogenesis: a network-based study

Hepatitis C virus (HCV) causes chronic liver disease worldwide. HCV Core protein (Core) forms the viral capsid and is crucial for HCV pathogenesis and HCV-induced hepatocellular carcinoma, through its interaction with the host factor proteasome activator PA28γ. Here, using BD-PowerBlot high-throughput Western array, we attempt to further investigate HCV pathogenesis by comparing the protein levels in liver samples from Core-transgenic mice with or without the knockout of PA28γ expression (abbreviated PA28γ(-/-)CoreTG and CoreTG, respectively) against the wild-type (WT). The differentially expressed proteins integrated into the human interactome were shown to participate in compact and well-connected cellular networks. Functional analysis of the interaction networks using a newly developed data warehouse system highlighted cellular pathways associated with vesicular transport, immune system, cellular adhesion, and cell growth and death among others that were prominently influenced by Core and PA28γ in HCV infection. Follow-up assays with in vitro HCV cell culture systems validated VTI1A, a vesicular transport associated factor, which was upregulated in CoreTG but not in PA28γ(-/-)CoreTG, as a novel regulator of HCV release but not replication. Our analysis provided novel insights into the Core-PA28γ interplay in HCV pathogenesis and identified potential targets for better anti-HCV therapy and potentially novel biomarkers of HCV infection.

Innate immunity and hepatitis C virus infection: a microarray's view

Hepatitis C virus (HCV) induces a chronic infection in more than two-thirds of HCV infected subjects. The inefficient innate and adaptive immune responses have been shown to play a major pathogenetic role in the development and persistence of HCV chronic infection. Several aspects of the interactions between the virus and the host immune system have been clarified and, in particular, mechanisms have been identified which underlie the ability of HCV to seize and subvert innate as well as adaptive immune responses. The present review summarizes recent findings on the interaction between HCV infection and innate immune response whose final effect is the downstream inefficient development of antigen-specific adaptive immunity, thereby contributing to virus persistence.

Hepatitis C virus infection in the Middle East and North Africa "MENA" region: injecting drug users (IDUs) is an under-investigated population

PURPOSE

Investigation of the injecting drug users (IDUs) population is becoming extremely critical and timely in light of the recent evidence that IDUs now act as the core of hepatitis C virus (HCV) epidemics in developed countries. The purpose of this article, therefore, is not only to review the epidemiology of HCV in the Middle East and North Africa (MENA) region, but also to see whether IDUs were adequately studied and whether harm reduction strategies to be applied for their protection have been set.

METHODS

A literature review was carried out of articles published within the last decade on HCV infection.

RESULTS

The gathered data showed that the population of IDUs is severely under-investigated throughout the whole region, possibly due to religious and cultural impediments.

CONCLUSION

In order to reduce the risk of HCV infection in IDUs, a set of recommendations are advanced emphasizing the urgent need for bio-behavioral studies in this population in order to help identify the source and mode of transmission and the genotypes of HCV involved. These results may allow the development of effective and, yet, socially acceptable intervention strategies. We believe that the role which IDUs play in sustaining HCV infection is also an under-investigated topic in many developing countries. Similar reviews and, hence, interventions should be initiated in these regions.

IL28B genetic variations are associated with high sustained virological response (SVR) of interferon-α plus ribavirin therapy in Taiwanese chronic HCV infection

Chronic hepatitis C virus (HCV) infection patients exhibit different sustained virological responses (SVRs) following the treatment with pegylated interferon-α (IFN-α) and ribavirin. Genome-wide association studies consistently linked SVR of IFN-α-based therapy to the IL28B single-nucleotide polymorphisms (SNPs) on chromosome 19q.13 in various populations. This study was undertaken to investigate the association of IL28B SNPs with SVR in a cohort of Taiwanese chronic HCV patients. Ten SNPs of IL28B were genotyped in 728 chronic HCV patients and 960 healthy controls. Genotype distributions, allele frequencies and haplotypes were tested for SVR and susceptibility in Taiwanese chronic HCV patients. Non-genotype 1 infection (adjusted P=3.3 × 10(-12), odds ratio (OR) 0.179; 95% confidence interval (CI): 0.110-0.290) and low HCV viral load (<400 000 IU ml(-1)) (adjusted P=3.5 × 10(-9), OR 0.299; 95% CI: 0.200-0.446) were two major factors identified for high SVR. Notably, eight IL28B SNPs including previously described disease-associated SNPs (Trend test P=0.005) were significantly associated with SVR. Our data indicate that IL28B polymorphisms are the essential contributing factors for high SVR in Taiwanese chronic HCV patients. Combination of virus genotyping and host genetic data may be used to select the optimal treatment regimes in IFN-based therapy.

Significance of changes in serum IL-18 and IL-1β levels in patients with chronic hepatitis C

AIM: To investigate the roles of serum IL-18 and IL-1β in the progression of chronic hepatitis C and explore the correlation between serum IL-18 and IL-1β levels and the efficacy of interferon (IFN) therapy.

METHODS: The levels of IL-18 and IL-1β in the serum of 30 chronic hepatitis C patients were determined before and after they received IFN therapy to observe changes in the serum levels of the two cytokines in different periods after HCV infection. Moreover, the correlations of serum IL-18 and IL-1β levels with ALT level, HCV genotype, IL-2 and IL-6 levels were analyzed. The differences in the serum levels of the two cytokines were also compared between patients with response and nonresponse to interferon treatment. The levels of serum cytokines were determined by ELISA. HCV genotypes were classified by direct sequencing. HCV RNA loads were determined by fluorescence quantitative PCR.

RESULTS: The level of IL-18 in the serum of chronic hepatitis C patients was higher than that of healthy controls (1077.44 ± 657.58 ng/L vs 259.92 ± 328.47 ng/L, P < 0.001). No significant difference in the level of serum IL-1β was noted between chronic hepatitis C patients and healthy controls though it had an upward trend over time (in contrast to a downward trend for IL-18). Severe patients had higher serum IL-1β level than mild ones (4.99 ± 1.44 ng/L vs 3.68 ± 0.76 ng/L, P < 0.05). The levels of the two cytokines were not significantly different among patients with different genotypes or subtypes of HCV. The level of IL-18 was positively correlated with that of IL-2 (r = 0.434, P < 0.05) rather than IL-6. The level of IL-1β was not correlated with those of IL-2 and IL-6. No significant differences were noted in the serum levels of IL-18 and IL-1β between patients with response and nonresponse to IFN therapy.

CONCLUSION: Serum IL-18 and IL-1β levels may be correlated with the chronicity and severity of hepatitis C but can not be used for prediction of the efficacy of IFN therapy.

Magnitude of CD8 T-cell responses against hepatitis C virus and severity of hepatitis do not necessarily determine outcomes in acute hepatitis C virus infection

AIM

We investigated the relationship between the magnitude of comprehensive hepatitis C virus (HCV)-specific CD8(+) T-cell responses and the clinical course of acute HCV infection.

METHODS

Six consecutive patients with acute HCV infection were studied. Analysis of HCV-specific CD8(+) T-cell responses was performed using an interferon-gamma-based enzyme-linked immunospot assay using peripheral CD8(+) T-cells, monocytes and 297 20-mer synthetic peptides overlapping by 10 residues and spanning the entire HCV sequence of genotype 1b.

RESULTS

Five patients presented detectable HCV-specific CD8(+) T-cell responses against a single and different peptide, whereas 1 patient showed responses against three different peptides. Neither the magnitude of HCV-specific CD8(+) T-cell responses nor the severity of hepatitis predicts the outcome of acute hepatitis. The maximum number of HCV-specific CD8(+) T-cells correlated with maximum serum alanine aminotransferase level during the course (r = 0.841, P = 0.036).

CONCLUSIONS

HCV-specific CD8(+) T-cell responses were detectable in all 6 patients with acute HCV infection, and 6 novel HCV-specific CTL epitopes were identified. Acute HCV infection can resolve with detectable HCV-specific CD8(+) T-cell responses, but without development of antibody against HCV.