Hepatitis C viral quasispecies and liver damage in patients with chronic hepatitis C virus infection

Correlation of IL28B rs12979860 genotype and gender with spontaneous clearance of HCV infection: a Pakistani cross-section study

AIM

There is a strong correlation of IL28B rs12979860 genetic variations and gender with spontaneous clearance of hepatitis C virus (HCV) infection.

MATERIALS & METHODS

HCV-infected subjects were categorized into HCV spontaneous clearance (SC) group and chronic hepatitis C (CHC) group on the basis of anti-HCV antibodies and HCV RNA level and follow-up of 6 months. 35 subjects were classified in SC group and 165 subjects were classified in CHC group. IL28B rs12979860 genotypes were determined by allele-specific PCR.

RESULTS & CONCLUSION

Multinominal logistic regression analyses revealed that both genders favor IL28B rs12979860 CT genotype (OR: 4.80; CI: 2.22-10.35; p = 0.0005) and (OR: 3.47; CI: 1.63-7.43; p = 0.001) for male and female, respectively, are significant in spontaneous clearance of HCV infection.

High resolution sequencing of hepatitis C virus reveals limited intra-hepatic compartmentalization in end-stage liver disease

BACKGROUND & AIMS

The high replication and mutation rate of hepatitis C virus (HCV) results in a heterogeneous population of viral sequences in vivo. HCV replicates in the liver and infected hepatocytes occur as foci surrounded by uninfected cells that may promote compartmentalization of viral variants. Given recent reports showing interferon stimulated gene (ISG) expression in chronic hepatitis C, we hypothesized that local interferon responses may limit HCV replication and evolution.

METHODS

To investigate the spatial influence of liver architecture on viral replication we measured HCV RNA and ISG mRNA from each of the 8 Couinaud segments of the liver from 21 patients undergoing liver transplant.

RESULTS

HCV RNA and ISG mRNA levels were comparable across all sites from an individual liver but showed up to 500-fold difference between patients. Importantly, there was no association between ISG and HCV RNA expression across all sites in the liver or plasma. Deep sequencing of HCV RNA isolated from the 8 hepatic sites from two subjects showed a similar distribution of viral quasispecies across the liver and uniform sequence diversity. Single genome amplification of HCV E1E2-envelope clones from 6 selected patients at 2 hepatic sites supported these data and showed no evidence for HCV compartmentalization.

CONCLUSIONS

We found no differences between the hepatic and plasma viral quasispecies in all patients sampled. We conclude that in end-stage liver disease HCV RNA levels and the genetic pool of HCV envelope sequences are indistinguishable between distant sites in the liver and plasma, arguing against viral compartmentalization.

LAY SUMMARY

HCV is an RNA virus that exists as a quasispecies of closely related genomes that are under continuous selection by host innate and adaptive immune responses and antiviral drug therapy. The primary site of HCV replication is the liver and yet our understanding of the spatial distribution of viral variants within the liver is limited. High resolution sequencing of HCV and monitoring of innate immune responses at multiple sites across the liver identified a uniform pattern of diversity and argues against viral compartmentalization.

Association of IL28B rs8099917 genotype and female sex with spontaneous clearance of hepatitis C virus infection: a Japanese cross-sectional study

Hepatitis C virus (HCV) infection is a serious global health problem. Previous studies have suggested that the interleukin 28B (IL28B) rs8099917 genotype is related to spontaneous clearance of HCV in Caucasian populations. Our objective was to investigate the association of the IL28B rs8099917 genotype with spontaneous clearance of HCV by community-dwelling Japanese. A cross-sectional community-based population study of 993 Japanese residents was conducted. Based on anti-HCV antibody and HCV RNA levels, 50 subjects were assigned to the spontaneous-clearance group, 155 to the chronic-infection group, and 788 to the control group. Logistic regression analysis was done to examine the roles of the IL28B rs8099917 genotype and sex. To analyze the interactions between these factors, an "IL28B rs809991 genotype × sex" interaction term was included in the multivariate analysis. Significantly more subjects in the spontaneous-clearance group than in the chronic-infection group had the favorable IL28B rs8099917 genotype and were female. Multivariate logistic regression analysis extracted the favorable IL28B rs8099917 TT genotype (odds ratio [OR] 9.39; 95% confidence interval [CI], 2.16-40.83, P = 0.003) and female sex (OR, 2.27; 95% CI, 1.16-4.45, P = 0.017) as factors contributing to the spontaneous clearance of HCV. No significant interaction was found between the IL28B rs8099917 genotype and sex (P for interaction = 0.428). Both the favorable IL28B rs8099917 genotype and female sex were associated with the spontaneous clearance of HCV in this Japanese population.

Influence of insulin resistance on the development of hepatocellular carcinoma after antiviral treatment for non-cirrhotic patients with chronic hepatitis C

Background

Insulin resistance is considered to be an important factor in the progression of fibrosis and the enhancement of the risk of hepatocellular carcinoma (HCC) for chronic hepatitis C patients. The aim of this study was to assess the effect of insulin resistance on the development of HCC by non-cirrhotic chronic hepatitis C patients treated with pegylated interferon alpha-2b (PEG-IFNα2b) and ribavirin.

Methods

This retrospective study consisted of 474 Japanese non-cirrhotic patients with chronic hepatitis C. The cumulative incidence of HCC was estimated using the Kaplan-Meier method, according to insulin resistance by the homeostasis model assessment of insulin resistance (HOMA-IR) and treatment outcome.

Results

The overall sustained virological response (SVR) rate was 45.1 % (214/474, genotype 1: 35.4 % [129/364] and genotype 2: 77.3 % [85/110]). Twenty-one (4.4 %) patients developed HCC during the follow-up period. The 5-year cumulative incidence of HCC of the SVR group (2.6 %) was significantly lower than that of the non-SVR group (9.7 %) (log-rank test: P = 0.025). In multivariable logistic regression analysis, HOMA-IR (≥2.5) (hazard ratio [HR] 12.8, P = 0.0006), fibrosis status (F3) (HR 8.85, P < 0.0001), and post-treatment alanine aminotransferase (ALT) level (≥40 U/L) (HR 4.33, P = 0.036) were independently correlated to the development of HCC. Receiver operating characteristic analysis to determine the optimal threshold value of HOMA-IR for predicting the development of HCC in the non-SVR group showed that the areas under the curve was high (0.80, cutoff value: 3.0). Only three patients (1.4 %) who achieved SVR developed HCC. Two of them had severe insulin resistance and did not show improvement in HOMA-IR after achieving SVR.

Conclusions

Insulin resistance has a strong impact on the development of HCC by non-cirrhotic patients who have PEG-IFNα2b and ribavirin treatment failure.

Recurrent HCV after liver transplantation-mechanisms, assessment and therapy

Chronic HCV infection is the leading indication for liver transplantation. However, as a result of HCV recurrence, patient and graft survival after liver transplantation are inferior compared with other indications for transplantation. HCV recurrence after liver transplantation is associated with considerable mortality and morbidity. The development of HCV-related fibrosis is accelerated after liver transplantation, which is influenced by a combination of factors related to the virus, donor, recipient, surgery and immunosuppression. Successful antiviral therapy is the only treatment that can attenuate fibrosis. The advent of direct-acting antiviral agents (DAAs) has changed the therapeutic landscape for the treatment of patients with HCV. DAAs have improved tolerability, and can potentially be used without PEG-IFN for a shorter time than previous therapies, which should result in better outcomes. In this Review, we describe the important risk factors that influence HCV recurrence after liver transplantation, highlighting the mechanisms of fibrosis and the integral role of hepatic stellate cells. Indirect and direct assessment of fibrosis, in addition to new antiviral therapies, are also discussed.

Comparison of quasispecies diversity of HCV between chronic hepatitis c and hepatocellular carcinoma by Ultradeep pyrosequencing

Backgrounds. Hepatitis C virus (HCV) exists as population of closely related genetic variants known as quasispecies. HCV quasispecies diversity is strongly influenced by host immune pressure on virus. Quasispecies diversity is expected to decline as host immune response to HCV decreases over natural course of progressing from chronic hepatitis C (CHC) to hepatocellular carcinoma (HCC). Methods. Ultradeep pyrosequencing (UDPS) was used to evaluate degree of quasispecies diversity in 49 patients infected with HCV including 26 with CHC and 23 with HCC. Whole structural protein of HCV genome was subjected to UDPS. Results. Shannon's indices for quasispecies diversity in HCV E1 were significantly lower in patients with HCC than in those with CHC. 14 amino acid positions differed significantly between two groups. Area under curve of ROC analysis for differentiating HCC from CHC was >0.8 for all of 14 amino acid positions. Conclusion. HCV quasispecies diversity as indicator of declining host immune functions was easily assessed by UDPS technology. Shannon's indices in 14 amino acid positions were found to differentiate between patients with CHC and those with HCC. Our data propose that degree of HCV quasispecies measured by UDPS might be useful to predict progression of HCC in chronic HCV patients.

Clinical significance of intra-host variability of Dengue-1 virus in venous and capillary blood

Dengue fever represents a major public health problem. Both viral and host immune factors are involved in severe infections. Humans and mosquito-vectors are infected with diverse viral populations that may play a role in viral adaptation and disease pathogenesis. Our objective was to analyse the intra-host genetic variability of dengue virus type 1 (DENV-1) in the venous and capillary blood and its relationships with the clinical presentation of dengue fever. Early serum samples were collected in 2009 from ten DENV-1-infected patients hospitalized in Santa Cruz de la Sierra, Bolivia. Partial viral envelope sequences were analysed at the inter-host and intra-host level. For each patient, an average of 56 clone sequences was analysed both in the venous sector and the capillary sector (from right and left hands). The ten consensus sequences were highly similar. The intra-host DENV-1 genetic variability was significantly lower in the venous sector than in the capillary sector, and in patients with haemorrhagic symptoms than in those without haemorrhagic symptoms, particularly in capillary samples. No relation was found with sex, age, dengue IgG-serological status, day of serum sampling, or viral load. Significant relationships were found between the clinical presentation of dengue fever and the variability of viral populations within hosts, particularly in capillary samples. The observed variability of envelope sequences at the early phase of dengue infection was not critically influenced by the previous dengue serological status of patients. An important part of viral microevolution may occur in the capillary sector and influence the mechanisms of severe forms.

Association between chronic hepatitis C virus infection and high levels of circulating N-terminal pro-brain natriuretic peptide

The association between HCV infection and myocardial disorders remains unclear. This study aimed to assess whether or not HCV infection influences myocardial dysfunction by the use of NT-proBNP, a sensitive marker of myocardial dysfunction. A total of 198 participants [99 patients with chronic HCV infection (aged 46-68 years) and 99 anti-HCV-negative sex and age matched controls] were examined. Serum HCV-RNA level and HCV genotype were tested and liver biopsy was done only for the patient group. The NT-proBNP concentration of the HCV patients (mean 71.6 ± 79.1 pg/ml; median 46.0 pg/ml, range 5.0-400.0) was significantly higher than that of the controls (mean 39.8 ± 24.4 pg/ml; median 35.8 pg/ml, range 7.0-108.0) (P < 0.05). 20.0 % of the HCV patients and 0.6 % of the controls had high NT-proBNP (higher than 125 pg/ml; the single cut off point for patients under 75 years of age) (P < 0.05). Stepwise multiple regression analysis revealed that chronic HCV infection was independently correlated with NT-proBNP level after adjustment for parameters that might influence NT-proBNP (P = 0.005). Our data suggest that chronic HCV infection is associated with increased NT-proBNP, indicating that chronic HCV infection might induce myocardial dysfunction.

Evaluation of the adverse effect of premature discontinuation of pegylated interferon α-2b and ribavirin treatment for chronic hepatitis C virus infection: results from Kyushu University Liver Disease Study

BACKGROUND AND AIMS

Pegylated interferon (PEG-IFN) α-2b and ribavirin (RBV) treatment of chronic hepatitis C virus (HCV) infection is associated with a substantially elevated risk of discontinuation. The aim of this study is to evaluate the reason for premature discontinuation during PEG-IFN α-2b and RBV treatment due to adverse effects in patients with chronic HCV infection.

METHODS

A total of 2871 Japanese patients who had chronic HCV infection treated with PEG-IFN α-2b and RBV were screened. We prospectively investigated the reasons for premature discontinuation of treatment classified by sex and age, and analyzed the timing of discontinuation.

RESULTS

Of the 2871 patients, 250 (8.7%) discontinued treatment because of adverse effects. The main reasons for premature discontinuation were neurovegetative symptoms (n = 77, 30.8%), depression-related syndrome (n = 46, 18.4%), hematologic effects (n = 41, 16.4%) and dermatologic effects (n = 27, 10.8%). The rate of discontinuation of treatment for patients aged ≥ 65 years was significantly higher than for patients aged < 65 years, for both men (P < 0.0001) and women (P = 0.0121). Moreover, the frequency of discontinuation due to neurovegetative symptoms, depression-related syndrome, and hematologic effects for men aged ≥ 65 years was significantly higher than for those aged < 65 years (P = 0.0001, P = 0.0016, and P = 0.0170, respectively), but not for women.

CONCLUSION

Premature discontinuation due to the adverse effects of PEG-IFN α-2b and RBV treatment by patients with chronic HCV infection is mainly due to neuropsychiatric symptoms and is more common for older than for younger patients.

Pegylated interferon α-2b plus ribavirin for Japanese chronic hepatitis C patients with normal alanine aminotransferase

AIM

  To investigate the efficacy and safety of a pegylated interferon (PEG-IFN) α-2b plus ribavirin (RBV) combination treatment for patients with chronic hepatitis C virus (HCV) infection who have persistently normal alanine aminotransferase (NALT).

METHODS

  This multicenter study included 989 patients with HCV genotype 1 (114 with NALT and 875 with elevated ALT) who received weight-based doses of PEG-IFN α-2b plus RBV for 48 weeks. We compared the sustained viral response (SVR) rates of patients with NALT and elevated ALT who received at least 80% or more of the target dosage of PEG-IFN α-2b and 60% or more of the target RBV (minimum acceptable dosage).

RESULTS

  No significant difference was found in the overall SVR rate between the NALT (42.1%) and elevated ALT groups (37.3%). No significant difference in the SVR rates was found between NALT (63.3%) and elevated ALT group (61.6%) patients who received minimum acceptable dosage. Multivariate analysis showed that age (<65 years old) and total cholesterol (≧220 mg/dL) were significantly independent positive factors associated with an SVR in the NALT group. Twenty-four weeks after treatment, an ALT increase above the normal range was observed for 34.0% (18 of 53) of the non-responsive group of NALT patients.

CONCLUSIONS

  The efficacy and safety of PEG-IFN α-2b plus RBV combination therapy for patients with chronic HCV infection are similar for patients with NALT and those with elevated ALT levels. These results indicate that patients with NALT should be considered for treatment with PEG-IFN α-2b plus RBV.

Excellent superiority and specificity of COBAS TaqMan HCV assay in an early viral kinetic change during pegylated interferon alpha-2b plus ribavirin treatment

BACKGROUND

An early virological response (EVR) after the start of interferon (IFN) treatment for chronic hepatitis C leads to a successful virological outcome. To analyze an association between sustained virological response (SVR) and EVR by comparing TaqMan with Amplicor assays in HCV genotype 1-infected patients treated with pegylated (PEG)-IFN alpha-2b plus ribavirin (RBV).

METHODS

We retrospectively analyzed a total of 80 HCV genotype 1 patients (39 SVR and 41 non-SVR patients), who received an enough dosage and a complete 48-week treatment of PEG-IFN alpha-2b plus RBV. Serum HCV RNA levels were measured by both TaqMan and Amplicor assays for each patients at Weeks 2, 4, 8 and 12 after the start of the antiviral treatment.

RESULTS

Of the 80 patients with undetectable HCV RNA by Amplicor, 17 (21.3%) patients were positive for HCV RNA by TaqMan at Weeks 12. The quantification results showed that no significant difference in the decline of HCV RNA level between TaqMan and Amplicor 10-fold method assays within the initial 12 weeks of the treatment was found. However, the qualitative analysis showed significant differences of the positive predictive rates for SVR were found between TaqMan (100% at weeks 4 and 100% at weeks 8) and Amplicor (80.0% and 69.6%, respectively).

CONCLUSIONS

The COBAS TaqMan HCV assay is very useful for monitoring HCV viremia during antiviral treatment to predict a SVR in HCV genotype 1 patients.

The quasispecies nature and biological implications of the hepatitis C virus

Many RNA viruses exist as a cloud of closely related sequence variants called a quasispecies, rather than as a population of identical clones. In this article, we explain the quasispecies nature of RNA viral genomes, and briefly review the principles of quasispecies dynamics and the differences with classical population genetics. We then discuss the current methods for quasispecies analysis and conclude with the biological implications of this phenomenon, focusing on the hepatitis C virus.

Increased rate of death related to presence of viremia among hepatitis C virus antibody-positive subjects in a community-based cohort study

The overall mortality of patients infected with hepatitis C virus (HCV) has not been fully elucidated. This study analyzed mortality in subjects positive for antibody to HCV (anti-HCV) in a community-based, prospective cohort study conducted in an HCV hyperendemic area of Japan. During a 10-year period beginning in 1995, 1125 anti-HCV-seropositive residents of Town C were enrolled into the study and were followed for mortality through 2005. Cause of death was assessed by death certificates. Subjects with detectable HCV core antigen (HCVcAg) or HCV RNA were considered as having hepatitis C viremia and were classified as HCV carriers; subjects who were negative for both HCVcAg and HCV RNA (i.e., viremia-negative) were considered as having had a prior HCV infection and were classified as HCV noncarriers. Among the anti-HCV-positive subjects included in the analysis, 758 (67.4%) were HCV carriers, and 367 were noncarriers. A total of 231 deaths occurred in these subjects over a mean follow-up of 8.2 years: 176 deaths in the HCV carrier group and 55 in the noncarrier group. The overall mortality rate was higher in HCV carriers than in noncarriers, adjusted for age and sex (hazard ratio, 1.53; 95% confidence interval, 1.13-2.07). Although liver-related deaths occurred more frequently among the HCV carriers (hazard ratio, 5.94; 95% confidence interval, 2.58-13.7), the rates of other causes of death did not differ between HCV carriers and noncarriers. Among HCV carriers, a higher level of HCVcAg (>or=100 pg/mL) and persistently elevated alanine aminotransferase levels were important predictors of liver-related mortality.

CONCLUSION

The presence of viremia increases the rate of mortality, primarily due to liver-related death, among anti-HCV-seropositive persons in Japan.

HCV genetic variability: from quasispecies evolution to genotype classification

HCV is a ssRNA virus belonging to the Flaviviruses and is found worldwide worldwide in humans. Following primary infection, persistent infection develops in more than 85% of cases, which in up to 30% of cases, may progress to liver disease, cirrhosis and hepatocellular carcinoma. The virus presents a high degree of genetic variability owing to the combination of a lack of proofreading by the RNA-dependent RNA polymerase and a high level of viral replication. This genetic variability allows the classification of genotypes, subtypes, isolates and quasispecies to which epidemiological and pathogenetic significance may be associated. The features and biological implications of HCV variability and of quasispecies dynamics in infection transmission, mechanisms of chronicity and resistance to antiviral therapy are discussed.

Association between the treatment length and cumulative dose of pegylated interferon alpha-2b plus ribavirin and their effectiveness as a combination treatment for Japanese chronic hepatitis C patients: project of the Kyushu University Liver Disease Study Group

AIM

The aim of the present study was to investigate the association between the length of the treatment period and the cumulative dose of pegylated interferon alpha-2b (peg-IFN alpha-2b) plus ribavirin (RBV) and their effectiveness in the treatment of chronic hepatitis C.

METHODS

Seven hundred and fifteen patients received peg-IFN alpha-2b plus RBV treatment for 48 weeks and 24 weeks for genotypes 1 (n = 586) and 2 (n = 129), respectively.

RESULTS

Sustained virological responses (SVR), defined as serum hepatitis C virus (HCV)-RNA undetectable at 24 weeks after the end of treatment, were 42.4% and 74.4% in genotypes 1 and 2, respectively, on an intention-to-treat analysis. SVR significantly increased with treatment length (4.7%, 36.4%, and 51.8% for < 24 weeks, 24-47 weeks, and 48 weeks, respectively, for genotype 1; and 28.6%, 57.1%, 78.3% for < 12 weeks, 12-23 weeks, and 24 weeks, respectively, for genotype 2). SVR significantly increased with total cumulative treatment dose (21.1%, 36.5%, and 52.9% with < 60%, 60-79%, and >or= 80% in peg-IFN dose; 29.6%, 51.1%, and 59.2% with < 60%, 60-79%, and >or= 80% in RBV dose) in genotype 1, although it did not differ significantly for genotype 2.

CONCLUSIONS

In peg-IFN alpha-2b plus RBV treatment for chronic hepatitis C, it is important to complete the target length of treatment and to continue the target dosage to achieve SVR, especially for genotype 1 patients.

High molecular weight form of adiponectin levels of Japanese patients with chronic hepatitis C virus infection

AIM

The aim of the present study was to clarify the correlation between serum adiponectin level and the properties of hepatitis C virus (HCV).

METHODS

A meal test was carried out for insulin resistance assessment in 81 patients with chronic HCV infection. Blood samples were taken before and after the test to measure serum insulin and plasma glucose (PG). The adiponectin level was measured by enzyme-linked immunosorbent assay in each patient.

RESULTS

Serum adiponectin levels were significantly correlated with the area under the insulin curve (AUC-insulin)during the meal test and with serum HCV-RNA level. Multiple regression analysis showed age to be a significant independent parameter associated with an increased adiponectin level, whereas male sex, fasting insulin, and serum HCV-RNA level were significant independent parameters associated with a decreased adiponectin level.

CONCLUSION

It is possible that insulin resistance in patients with chronic HCV infection is related to adiponectin secretion.

Quasispecies and its impact on viral hepatitis

Quasispecies dynamics mediates adaptability of RNA viruses through a number of mechanisms reviewed in the present article, with emphasis on the medical implications for the hepatitis viruses. We discuss replicative and non-replicative molecular mechanisms of genome variation, modulating effects of mutant spectra, and several modes of viral evolution that can affect viral pathogenesis. Relevant evolutionary events include the generation of minority virus variants with altered functional properties, and alterations of mutant spectrum complexity that can affect disease progression or response to treatment. The widespread occurrence of resistance to antiviral drugs encourages new strategies to control hepatic viral disease such as combination therapies and lethal mutagenesis. In particular, ribavirin may be exerting in some cases its antiviral activity with participation of its mutagenic action. Despite many unanswered questions, here we document that quasispecies dynamics has provided an interpretation of the adaptability of the hepatitis viruses, with features conceptually similar to those observed with other RNA viruses, a reflection of the common underlying Darwinian principles.

Immunopathogenesis in hepatitis C virus cirrhosis

HCV (hepatitis C virus) has a high propensity to persist and to cause chronic hepatitis C, eventually leading to cirrhosis. Since HCV itself is not cytopathic, liver damage in chronic hepatitis C is commonly attributed to immune-mediated mechanisms. HCV proteins interact with several pathways in the host's immune response and disrupt pathogen-associated pattern recognition pathways, interfere with cellular immunoregulation via CD81 binding and subvert the activity of NK (natural killer) cells as well as CD4(+) and CD8(+) T-cells. Finally, HCV-specific T-cells become increasingly unresponsive and apparently disappear, owing to several possible mechanisms, such as escape mutations in critical viral epitopes, lack of sufficient help, clonal anergy or expansion of regulatory T-cells. The role of neutralizing antibodies remains uncertain, although it is still possible that humoral immunity contributes to bystander damage of virally coated cells via antibody-dependent cellular cytotoxicity. Cytotoxic lymphocytes kill HCV-infected cells via the perforin/granzyme pathway, but also release Fas ligand and inflammatory cytokines such as IFNgamma (interferon gamma). Release of soluble effector molecules helps to control HCV infection, but may also destroy uninfected liver cells and can attract further lymphocytes without HCV specificity to invade the liver. Bystander damage of these non-specific inflammatory cells will expand the tissue damage triggered by HCV infection and ultimately activate fibrogenesis. A clear understanding of these processes will eventually help to develop novel treatment strategies for HCV liver disease, independent from direct inhibition of HCV replication.

Non-structural protein 4A of Hepatitis C virus accumulates on mitochondria and renders the cells prone to undergoing mitochondria-mediated apoptosis

Non-structural protein 4A (NS4A) of Hepatitis C virus (HCV) functions as a cofactor for NS3 by forming a complex with it to augment its enzymic activities. NS4A also forms a complex with other HCV proteins, such as NS4B/NS5A, to facilitate the formation of the viral RNA replication complex on the endoplasmic reticulum (ER) membrane. In addition to its essential role in HCV replication, NS4A is thought to be involved in viral pathogenesis by affecting cellular functions. In this study, it was demonstrated that NS4A was localized not only on the ER, but also on mitochondria when expressed either alone or together with NS3 in the form of the NS3/4A polyprotein and in the context of HCV RNA replication in Huh7 cells harbouring an HCV RNA replicon. Moreover, NS4A expression altered the intracellular distribution of mitochondria significantly and caused mitochondrial damage, as evidenced by the collapsed mitochondrial transmembrane potential and release of cytochrome c into the cytoplasm, which led ultimately to induction of apoptosis through activation of caspase-3, but not caspase-8. Consistently, Huh7 cells expressing NS3/4A and those harbouring an HCV RNA replicon were shown to be more prone to undergoing actinomycin D-induced, mitochondria-mediated apoptosis, compared with the control Huh7 cells. Taken together, these results suggest the possibility that HCV exerts cytopathic effect (CPE) on the infected cells under certain conditions and that NS4A is responsible, at least in part, for the conditional CPE in HCV-infected cells.

Hepatitis C virus population dynamics during infection

Hepatitis C virus (HCV) behaves as an evolving viral quasispecies in its continuously changing environment. The study of HCV quasispecies population dynamics in experimental models and infected patients can provide useful information on factors involved in the HCV life cycle and pathogenicity. HCV quasispecies variability also has therapeutic implications, as the continuous generation and selection of fitter or truly resistant variants can allow the virus to escape control by antiviral drugs.

Alanine transaminase levels in the year before pregnancy predict the risk of hepatitis C virus vertical transmission

Vertical transmission is the most common route of hepatitis C virus (HCV) infection in children. Transmission risk factors have been described, but most risk factors can only be evaluated using expensive laboratory exams. The aim of the present study was to evaluate whether maternal alanine transaminase (ALT) levels before pregnancy correlate with HCV vertical transmission. Seventy-four transmitting and 403 nontransmitting mothers were evaluated. All mothers enrolled had two ALT determinations in the last year before pregnancy, at least 6 months apart. Mothers were divided into two groups: mothers with persistently normal serum ALT levels and mothers with abnormal ALT levels. In the second group both mothers with constantly raised or with fluctuating ALT levels (one normal and one raised determination) were included. ALT was defined as raised if higher than twice the upper limit of normal. Abnormal ALT levels were found in 39/74 (52.7%) HCV transmitting mothers and in 146/403 (32.6%) nontransmitting mothers (P = 0.008; relative risk 1.96; 95% confidence limits 1.19-3.23). The risk of transmission from mothers with constantly raised ALT levels was more evident than that from mothers with fluctuating ALT levels. Increased ALT levels may reflect a more severe liver disease and a higher viral load, factors known to be associated with vertical transmission. ALT determination, a simple, widely available and inexpensive test, may help in identifying mothers with an increased risk of HCV vertical transmission.

Helper T cell cytokine response to ribavirin priming before combined treatment with interferon alpha and ribavirin for patients with chronic hepatitis C

The viral genotype and serum viral level influence the response to interferon (IFN) treatment in patients with chronic hepatitis C virus (HCV) viremia. The aim of this study was to investigate a possible relationship between early virological response and helper T (Th) cell cytokine expansion by 4 weeks of ribavirin (RIB) alone followed by IFN and RIB combined in patients with genotype 1b and a high HCV RNA level, patients reported not to respond well to IFN treatment. Eighty-one patients with genotype 1b and a high HCV RNA level, over 100 international unit per milliliter (KIU/mL) (by Amplicor HCV Monitor), were assigned to two groups: Group A (N = 40) with a 4-week RIB administration followed by a 24-week combination treatment, and Group B (N = 41) with a 24-week combination treatment only. Blood was obtained from each patient on the following schedule: at Baseline (4 weeks before day 0), on day 0 (initiation day of the RIB and IFN combination treatment), weeks 4 (4 weeks after the start of the combination treatment), and at the end of the combination treatment. Flow cytometry was used to investigate sequential changes of IFN-gamma producing (Th1) and interleukin-4 producing (Th2) cells from whole blood samples after stimulation with PMA and ionomycin. Serum HCV RNA clearances were 32.5% at week 4, 43.2% at week 8, 85.7% at the end of the combination treatment, and 22.9% within the 24-week follow-up in Group A; and 17.1%, 27.0%, 66.7% and 19.4% in Group B, respectively. The mean Th1/Th2 ratio significantly increased from 15.9 at baseline to 17.6 at day 0 with a decrease of Th2 cells, and then significantly decreased from 17.6 at day 0 to 15.5 at week 4 in Group A, while there was no significant change in Group B between baseline and day 0. In Group A, 13 patients with HCV RNA clearance within 4 weeks had a significantly increased Th1/Th2 ratio, from 14.0 at baseline to 22.1 at day 0, and then a significantly decreased ratio, from 22.1 at day 0 to 15.0 at week 4, while the others had no significant change in the ratio. RIB administration preceding combined treatment of RIB with IFN was more effective in Th2 cell expansion than the usual combined treatment of IFN with RIB and led to a relatively early virological clearance in chronic hepatitis C patients with genotype 1b and a high HCV RNA level.

Strenuous physical labor is important as a cause of elevated alanine aminotransferase levels in Japanese patients with chronic hepatitis C viremia

To clarify the influence of lifestyle habits on the elevated alanine aminotransferase (ALT) levels deterioration of Japanese patients with chronic hepatitis C virus (HCV) viremia, we investigated the effects of smoking, drinking, and physical labor on the disease course of the residents living in a rural area of Kyushu, Japan. The data of patients with chronic HCV viremia and control subjects without HCV infection were analyzed retrospectively from 1986 to 1992 and prospectively from 1993 to 2000. In 2000, a questionnaire was given to 268 HCV-infected patients and 275 control subjects to survey for the lifestyle habits. The data of serial ALT level testing during the observation period was used as a measure of liver damage: 183 HCV patients (68.3%) and 10 control subjects (3.6%) had abnormal ALT levels greater than 35 IU/1 for more than half of their observation period. The percentage of HCV patients with elevated ALT levels significantly increased with the daily consumption of alcohol (p < 0.0001), the length of time spent in strenuous physical labor per day (p = 0.0056), and the number of cigarettes smoked per day (p = 0.0003). A stepwise logistic regression analysis showed male sex (p = 0.003), platelet counts (p < 0.001), strenuous physical labor (p = 0.002), and drinking history (p = 0.007) to be significantly associated with the elevated ALT levels of HCV patients. When strenuous physical labor was done for over 2 h, the probability of elevated ALT levels was increased compared with patients engaging in strenuous physical labor under 2 h (estimated odds ratio = 1.82 [under 2 h], 20.60 [over 2 h]). Interestingly, strenuous physical labor was extracted before alcohol consumption as a significant factor in the elevated ALT levels. Among the control subjects, only the amount of alcohol consumed per day (p = 0.0001) was significantly associated with the elevated levels. These data suggests that strenuous physical labor over a long period of time might be related to elevated ALT levels in patients with chronic HCV viremia as well as drinking.

Detection of apoptotic caspase activation in sera from patients with chronic HCV infection is associated with fibrotic liver injury

Chronic hepatitis C virus (HCV) infection is characterized by inflammatory liver damage and is associated with a high risk of development of cirrhosis and hepatocellular carcinoma. Although histological examination of liver biopsies is currently the gold standard for the detection of early liver damage, there is a strong need for better noninvasive methods. We recently demonstrated that the proapoptotic activation of caspases is considerably enhanced in histological sections from HCV-infected liver tissue, suggesting an important role of apoptosis in liver damage. Here, we investigated whether caspase activation is detectable also in sera from patients with chronic HCV infection. Using a novel enzyme-linked immunosorbent assay that selectively recognizes a proteolytic neoepitope of the caspase substrate cytokeratin-18, we demonstrate that caspase activity is markedly increased in the sera of HCV patients. Interestingly, while 27% of patients with chronic HCV infection showed normal aminotransferase levels despite inflammatory and fibrotic liver damage, more than 50% of those patients exhibited already elevated serum caspase activity. Moreover, 30% of patients with normal aminotransferase but elevated caspase activity revealed higher stages of fibrosis. In conclusion, compared with conventional surrogate markers such as aminotransferases, detection of caspase activity in serum might be a more sensitive method of detecting early liver injury. Thus, measurement of caspase activity might provide a novel diagnostic tool, especially for patients with normal aminotransferases but otherwise undiagnosed histologically active hepatitis and progressive fibrosis.

Role of viral and host factors in HCV persistence: which lesson for therapeutic and preventive strategies?

Several lines of evidence support the view that hepatitis C virus is not directly cytopathic for infected host cells and that the immune response plays a central role in the pathogenesis of liver damage. Innate and adaptive immune responses are induced in most individuals infected with hepatitis C virus but are insufficient to eliminate the virus. The mechanisms responsible for this failure are largely unknown but the kinetics of hepatitis C virus replication relative to the priming of the adaptive responses may exert a profound influence on the balance between virus and host. Immediately after hepatitis C virus infection, the virus replicates efficiently, inducing the production of type I interferons. However, the rapid increase in viral replication seems to be ignored by the adaptive immune response, and after a short interval from exposure, viral load can reach levels comparable to those of patients with established persistent infection. The CD8-mediated response shows functional defects, with impaired production of interferon-gamma, low perforin content, decreased capacity of expansion and lysis of target cells. Late appearance and functional defects of T cells in hepatitis C virus infection might be the result of the rapid increase of the viral load that could create the conditions for exhaustion of the adaptive response or reflect an insufficient function of the innate immune response. This possibility is suggested by in vitro studies showing that hepatitis C virus gene products can interfere with the anti-viral activity of type I interferons and natural killer cells as well as with the maturation of dendritic cells. While T-cell defects are reversed in a minority of infected individuals who succeed in controlling the infection, the T-cell impairment becomes progressively more profound as infection progresses to chronicity. In this situation, therapeutic restoration of adaptive responses may represent a rational strategy to obtain resolution of infection and to complement available therapies. The peculiar kinetics of hepatitis C virus replication and T-cell induction soon after infection may have important implications also for the design of protective vaccines since memory responses may not be able to precede the early peak of viral replication. Therefore, vaccines against hepatitis C virus may be unable to prevent infection but may rather be effective in facilitating a self-limited evolution of infection.

Confirmation of nosocomial hepatitis C virus infection in a hemodialysis unit

OBJECTIVES

To investigate a hepatitis C virus (HCV) outbreak in a hemodialysis unit and determine the source of transmission.

METHODS

We have prospectively investigated the epidemiology of hemodialysis-related HCV infection in a single unit since 1989. In September 2000, acute hepatitis C (AH-C) was diagnosed in 5 patients by alanine aminotransferase elevation and HCV genotype 1b viremia without antibody to HCV. We surveyed the epidemiologic situation and performed polymerase chain reaction sequence analysis of the HCV 5'-noncoding (5'NC) region in the patients for comparison with 9 patients with chronic HCV genotype 1b viremia.

RESULTS

Sequence analysis of the 5'NC region showed the consistency in the 5 independent clones from each AH-C patient and those from each chronic HCV viremia patient and no quasispecies over time in the clones of any of 14 analyzed patients. All AH-C patients had the same sequencing of the 6 variations in the region with the only other patient. A saline ampoule, used for heparin solution during hemodialysis, had a recap function. It was difficult to determine whether the ampoule was new or had already been used. The source-patient often underwent hemodialysis before the AH-C patients and most of their hemodialysis-related medicine was prepared during the source-patient's treatment. These findings suggested a high possibility that the AH-C patients shared a single heparin-saline solution ampoule contaminated by HCV from the source-patient.

CONCLUSION

Nosocomial HCV infection occurred as a result of poor infection control practice when a patient with chronic HCV viremia received treatment prior to other hemodialysis patients.

Hepatitis C virus quasispecies in the natural course of HCV-related disease in patients with haemophilia

Patients with haemophilia show high prevalence of hepatitis C infection but low rate of progressive liver disease when they are not co-infected with HIV. The balance between host immune system and hepatitis C virus (HCV) variability seems to play a major role in the evolution of the HCV-related disease. To address this point we have studied, in a group of selected patients with haemophilia, the composition and in some cases the evolution, of the highest variable envelope gene within the hypervariable region 1 (HVR1) of the HCV, which is the region more directly exposed to the host immune response. Five of 12 patients show a very high homogeneity of the HVR1 and four of those had severe progressive liver disease. These results seem to confirm the major role of the immunity in driving the variability of the HCV rather than the high degree of different HCV strains to which haemophiliacs have been in touch with, during their long-term replacement therapy. Our results seem in keeping with other studies on different type of patients, where a low degree of quasispecies variability has been demonstrated in relationship with the progression and the severity of their liver disease.

Granulocyte and Monocyte Adsorptive Apheresis for Patients with Chronic Hepatitis C Virus Infection: A Report on Six Cases with High Plasma Viremia

Granulocytes and monocytes/macrophages (GM) are known to constitute extra-hepatic sites for hepatitis C virus (HCV) replication and dissemination. Accordingly, we thought that selective GM adsorptive apheresis (GMA) might contribute to the treatment of HCV in patients with high viremia (HCV-RNA > 100 kIU/mL). Of six patients (three males and three females), mean age 62.2 years, five had not responded to interferon-alpha (INF-alpha) and one was INF-alpha naïve. Each patient received five GMA sessions, once a week for 5 weeks. The two antecubital veins were used as blood access and return lines and the apheresis was performed at 30 mL/min for 60 min. Treatment efficacy was assessed by monitoring changes in plasma HCV-RNA and aminotransferase. Granulocyte and monocyte/macrophage adsorptive apheresis was well tolerated. During each GMA, there was on average a 52.9% fall in plasma HCV-RNA, but HCV-RNA increased again during the time before the next GMA. There was no marked change in either aminotransferase during GMA. Furthermore, beyond the last GMA, HCV-RNA increased together with worsening aminotransferase in three of six patients. In conclusion, it would appear that GMA can partially reduce plasma HCV and GMA at a frequency of one session/week for 5 consecutive weeks but that this was inadequate to induce a sustained decrease in plasma HCV-RNA in patients with high viremia without simultaneous administration of antiviral medications. The most effective frequency of GMA needs to be determined in future clinical studies.

Clinical management of HCV carriers with normal aminotransferase levels

An ad hoc committee appointed by the Italian Association for the Study of the Liver (AISF) proposed these Practice Guidelines for the management of HCV carriers with persistently normal aminotransferase levels. Only stringent ALT determinations will make it possible to distinguish these subjects from those in temporary biochemical remission. The overall prevalence in Italy has been estimated between 1.5 and 10.6%. HCV RNA quantitation and genotype determination are not predictors of the presence and severity of liver damage nor correlate with the outcome of the disease, and should not be used in clinical practice for the management and surveillance of HCV carriers with normal ALT. Only a minority of HCV carriers with normal ALT levels show a normal morphological picture (true 'healthy carriers'). Disease activity is mild in most cases; fibrosis is generally mild and cirrhosis is very rare. Histological activity, as monitored by sequential liver biopsies, seems to have very slow evolution. HCV carriers should not undergo liver biopsy on a routine basis. Liver biopsy can be reasonably proposed only in selected cases. Until the results of studies with PEG interferon plus ribavirin are available, HCV carriers should not receive antiviral treatment outside controlled experimental studies.

Comprehensive review of hepatitis C for psychiatrists: risks, screening, diagnosis, treatment, and interferon-based therapy complications

Hepatitis C is an RNA virus responsible for chronic infection in at least 4 million Americans. Patients are often unaware that they have contracted the virus until the appearance of long-term consequences of the infection, primarily cirrhosis and hepatocellular carcinoma. Many patients with hepatitis C have comorbid psychiatric and/or substance abuse disorders. Treatments for hepatitis C infection are based on interferon-alfa therapy and have shown increasing effectiveness in recent years; however, interferon-alfa therapy also poses significant risks for physical and neuropsychiatric side effects. Since psychiatrists often serve as primary caregivers for patients who are at higher risk for hepatitis C infection, knowledge about the diagnosis, prognosis, and treatment of this disease is needed. In the first half of this article, the authors review the epidemiology, transmission, pathophysiology and disease course of hepatitis C, as well as the neuropsychiatric complications of hepatitis C infection. They also discuss the incidence of comorbid psychiatric disorders in patients with hepatitis C infection and consider the impact of the infection on patients' quality of life. The authors then provide an overview of the clinical management of HCV infection, including screening procedures, decision-making about treatment, available treatments (interferon-alfa, pegylated interferon-alpha, combination therapy with interferon and ribavirin) and their side effects and potential drug-drug interactions, and prediction of treatment response. The authors then discuss management of the neuropsychiatric complications of treatment with interferon-alpha and ribavirin, including depression, mania and psychosis, and cognitive and neurological complications. The final section of the article focuses on special issues related to the treatment of hepatitis C infection in patients with substance abuse or dependence and/or other comorbid psychiatric illness.

Hepatitis C virus genetic variability: pathogenic and clinical implications

HCV is variable because of the properties of the viral RdRp, high levels of replication, and large population sizes. The Darwinian evolution of HCV has been characterized by the emergence of the HCV genotypes, including six main types and a large number of subtypes. The study of HCV genotype epidemiology provides useful information on the worldwide HCV epidemics. The HCV genotype is an important predictor of the response to IFN-alpha-based antiviral therapy, and genotype determination is currently used to tailor treatment indications. In addition, HCV circulates and behaves in infected individuals as mixtures of closely related but distinct viral populations referred to as quasispecies. This particular nature of the virus influences its transmission, the pathogenesis of liver disease and extra-hepatic manifestations, and the outcome during and after antiviral therapy or after transplantation for HCV-related end-stage liver disease. Further studies are needed to understand better the implications of HCV quasispecies diversity in the pathophysiology of HCV infection.

Apoptosis in hepatitis C virus infection

Infection with hepatitis C virus (HCV) is characterized by inflammatory liver damage and a long viral persistence associated with an increased risk of developing hepatocellular carcinoma. Both in liver damage and in oncogenesis a disturbance of apoptosis has been implicated, although the underlying mechanisms in these apparently opposite processes are incompletely understood. HCV-triggered liver injury is mediated mainly by host immune mechanisms and eventually by direct cytopathic effects of HCV. Recent data shows that caspase activation, either triggered by death ligands, other cytokines, granzyme B or HCV proteins, is considerably upregulated in HCV-infected liver. Interestingly, caspase activation appears to correlate closely with the inflammatory response. Data about the role of single HCV proteins, either in cultured cells or transgenic animals models, however, are contradictory, as both pro- and anti-apoptotic effects have been observed. Nevertheless, apoptosis induction upon HCV infection may critically contribute to liver damage, while inhibition of apoptosis may result in HCV persistence and development of hepatocellular carcinoma.

TT-virus infection in Japanese general population and in hemodialysis patients

To determine TT virus (TTV) prevalence and the persistence of viremia, we prospectively did cross-sectional and longitudinal studies using by the polymerase chain reaction to test the successive sera of 150 Japanese hemodialysis patients and compared these with those of 166 residents of a rural Japanese area endemic for hepatitis C virus (HCV). TTV DNA positivity was significantly higher in 50 (30.1%) of the residents than in 25 (16.7%) of the patients in 1997 (P < 0.05). TTV DNA positively in the patients was not associated with HCV RNA positivity and also increased with the number of blood transfusions and decreased with the duration of hemodialysis, but not significantly. Longitudinal study from 1997 to 1999 showed that persistent TTV DNA positivity was found significantly more often in 35 (21.1%) of the residents than in 13 (8.6%) of the patients (P < 0.05), and that persistent TTV DNA negativity was found significantly more often in 103 (68.7%) of the patients than in 91 (54.8%) of the residents (P < 0.05). Of the 25 patients and 50 residents TTV DNA positive in 1997, TTV DNA was eliminated more often in 12 (48.0%) patients than in 15 (30.0%) residents over the three years, but the difference was not significant. The route of TTV transmission might differ from HCV in that it could be nonparenteral. TTV was less prevalent in hemodialysis patients than residents, and the virus was more often eliminated by hemodialysis patients than by residents during the three-year observation period, possibly because of the effect of the hemodialysis procedure.

Increased frequency of IFN-gamma-producing peripheral CD8+ T cells with memory-phenotype in patients with chronic hepatitis C

To identify the capacity for cytokine production and the phenotypic characteristics of peripheral CD8(+) T cells in patients with chronic hepatitis C, 31 patients with chronic hepatitis C and 22 healthy controls were studied at the single cell level by three-color flow cytometry. Whole blood was stained with surface CD8, intracellular interferon-gamma (IFN-gamma), and interleukin-4 (IL-4), surface CD8, CD28, and intracellular IFN-gamma after stimulation with PMA plus ionomycin, and then surface CD8, CD45RA, and CD28. IFN-gamma-producing peripheral CD8(+) T cells were found frequently in patients than in controls (P < 0.05), whereas IL-4-producing peripheral CD8(+) T cells were not. Although the frequency of peripheral CD28(+)CD8(+) and CD28(-)CD8(+) T cells in patients was not different from that of controls, CD28(+)CD8(+) T cells exceeded CD28(-)CD8(+) T cells in the capacity for IFN-gamma-production after mitogenic stimulation (P < 0.01). In a more detailed analysis of the CD28(+)CD8(+) T cells, CD45RA(-)CD28(+)CD8(+) T cells, defined phenotypically as memory cells, were found frequently in patients than in controls (P < 0.05). There were no significant correlations between the frequency of IFN-gamma-producing peripheral CD8(+) T cells and hepatitis C virus RNA level or serum alanine aminotransferase level in patients. These data suggest that functionally T cytotoxic type 1 and memory CD8(+) T cells are predominant in the peripheral blood of chronic hepatitis C patients and that such activated CD8(+) T cells are associated with liver damage.

Evolutionary trends of the first hypervariable region of the hepatitis C virus E2 protein in individuals with differing liver disease severity

Hepatitis C virus (HCV) exists as a complex swarm of genetically related viruses known as a quasispecies. Recent work has shown that quasispecies complexity and evolutionary rates are associated with the outcome of acute infection. Knowledge of how the virus population evolves at different stages of chronic infection is less clear. We have studied rates of evolution of the first hypervariable region (HVR1) of the E2 envelope protein in six individuals with disparate liver disease severity. These data show that virus populations present in individuals with mild non-progressive liver disease evolve in a typical Darwinian fashion, with a consistent accumulation of non-synonymous (amino acid-changing) substitutions. By contrast, the virus population remains relatively static in individuals with severe progressive liver disease. Possible mechanisms for this disparity are discussed.

Hypervariable region 1 quasispecies in hepatitis C virus genotypes 1b and 3 infected patients with normal and abnormal alanine aminotransferase levels

The role of hepatitis C virus (HCV) heterogeneity in the severity of chronic hepatitis C infection remains unclear. Our aim was to study the hypervariable region 1 (HVR1) heterogeneity in patients with chronic hepatitis C infected with genotype 1b or 3 and with normal or abnormal alanine aminotransferase (ALT). HVR1 quasispecies were assessed by single strand conformational polymorphism (SSCP) in 67 patients with chronic hepatitis C, including 35 with persistently normal ALT and 32 with abnormal ALT. Sixty-two patients underwent a liver biopsy. Among the 67 patients, 40 were infected with genotype 1b and 27 with genotype 3. In univariate analysis, low heterogeneity (<or= 3 bands at SSCP) was significantly associated with normal ALT (P < 0.001), milder histological lesions (activity, P=0.02; fibrosis, P=0.04), and at the limit of significance for genotype 1b (P=0.07). In multivariate analysis, low heterogeneity was significantly and independently associated with normal ALT (P=0.09) and genotype 1b (P=0.03). In patients with chronic hepatitis C, a low viral heterogeneity is significantly and independently associated with normal ALT and genotype 1b. These results are consistent with the view that patients with normal ALT have a different immune response against HCV resulting in a low HCV heterogeneity.

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.

Longitudinal evaluation of the structure of replicating and circulating hepatitis C virus quasispecies in nonprogressive chronic hepatitis C patients

In previous cross-sectional studies, we demonstrated that, in most patients with chronic hepatitis C, the composition and complexity of the circulating hepatitis C virus (HCV) population do not coincide with those of the virus replicating in the liver. In the subgroup of patients with similar complexities in both compartments, the ratio of quasispecies complexity in the liver to that in serum (liver/serum complexity ratio) of paired samples correlated with disease stage. In the present study we investigated the dynamic behavior of viral population parameters in consecutive paired liver and serum samples, obtained 3 to 6 years apart, from four chronic hepatitis C patients with persistently normal transaminases and stable liver histology. We sequenced 359 clones of a genomic fragment encompassing the E2(p7)-NS2 junction, in two consecutive liver-serum sample pairs from the four patients and in four intermediate serum samples from one of the patients. The results show that the liver/serum complexity ratio is not stable but rather fluctuates widely over time. Hence, the liver/serum complexity ratio does not identify a particular group of patients but a particular state of the infecting quasispecies. Phylogenetic analysis and signature mutation patterns showed that virtually all circulating sequences originated from sequences present in the liver specimens. The overall behavior of the circulating viral quasispecies appears to originate from changes in the relative replication kinetics of the large mutant spectrum present in the infected liver.

Hepatitis C virus. The importance of viral heterogeneity

Although recent evidence indicates that the quasispecies nature of HCV constitutes a critical strategy for the virus to survive in the host, the mechanisms of viral persistence remain unknown. Similarly, the correlates of immune protection in a limited proportion of individuals who succeed in clearing HCV are still largely undefined. Understanding the mechanisms of sterilizing immunity is essential for devising preventive measures against HCV and unraveling how the virus eludes such immunity. As in other viral infections, the complex interactions between the virus and the host early in the course of HCV infection probably determine the outcome of the disease (i.e., resolution or persistence). The evidence now accumulated on HCV and other models of viral infection is compatible with the hypothesis that both cellular and humoral components are needed for definitive viral clearance. Nevertheless, detailed studies of the specific cellular and humoral immune responses during the incubation period and the acute phase of hepatitis C, in relation to the viral quasispecies evolution and the clinical outcome, are still lacking both in humans and in the chimpanzee model. Until such studies are performed, most ideas of viral clearance mechanisms remain hypothetical, and the immunologic basis of HCV clearance will continue to be inferred from associations rather than from causal relationships.

Quantitation of hepatic hepatitis C virus RNA in patients with chronic hepatitis C. Relationship with severity of disease, viral genotype and response to treatment

BACKGROUND/AIMS

To determine the correlation between hepatic hepatitis C virus (HCV) RNA and histological lesions, viral genotype or response to alpha interferon therapy.

METHODS

Forty-three patients with chronic hepatitis C (14 sustained responders (SR) and 29 non-sustained responders (NSR)) were studied. A liver tissue sample was obtained before and 1 year after treatment. Quantitation of hepatic HCV-RNA was performed by competitive PCR.

RESULTS

Before treatment, HCV-RNA was detectable in all liver samples. There was no association between hepatic HCV-RNA and the severity of liver lesions. There was a significant association between old age and hepatic HCV-RNA (P = 0.03). There was an association, at the limit of significance, between genotype 1 and high hepatic HCV-RNA amounts (15 x 106 and 4.1 x 10(6) copies/g, P = 0.05). Pre-treatment hepatic HCV-RNA amounts were lower in SRs than in others (0.65 x 10(6) and 13.2 x 10(6) copies/g, P = 0.0002). After treatment, no liver HCV-RNA was detectable in the SRs while in the NSRs, the HCV-RNA amounts were unchanged.

CONCLUSIONS

The amount of hepatic HCV-RNA is correlated to genotype and response to interferon therapy but not to histologic lesions. Hepatic HCV-RNA clearance is observed in SRs, suggesting viral eradication.

Acute hepatitis C among Japanese hemodialysis patients: a prospective 9-year study

OBJECTIVES

The aims of this prospective survey were to determine the incidence and clinical characteristics of newly acquired hepatitis C virus (HCV) infection in hemodialysis patients after the start of antibody to HCV (anti-HCV) screening for blood products in Japan in 1989.

METHODS

In serial serum samples from 269 hemodialysis patients who were followed over a mean period of 6.6 yr (+/- 2.1 yr) from 1990 to 1998, HCV RNA and anti-HCV were detected by reverse transcription-polymerase chain reaction and second generation ELISA, respectively.

RESULTS

During the observation period, newly acquired HCV infection was found in 26 (15.4%) of the 169 hemodialysis patients without anti-HCV or HCV RNA at entry, an annual incidence rate of 2.59%. Of these 26, only four had a history of blood transfusion, one of whom had received the blood transfusion after 1992, the year in which screening of blood products for anti-HCV by second-generation ELISA was introduced in Japan. Persistent HCV viremia was found in 17 (65.4%) of the 26 patients; the other nine (34.6%) had transient HCV infection. The mean period of continuous ALT abnormality was significantly longer in the former (12.4+/-13.6 months) than in the latter (1.9+/-3.5 months) (p = 0.0067). However, only three (17.6%) of 17 patients with chronic HCV viremia had continuous ALT abnormality for more than 24 months; in all of them, ALT eventually normalized.

CONCLUSIONS

These findings indicate that newly acquired HCV infection has continued to occur in hemodialysis patients after the initiation of anti-HCV screening of blood products and that the abnormal ALT found in these patients is related to HCV chronicity.

Seroepidemiology of TT virus infection and relationship between genotype and liver damage

TT virus (TTV) has been identified in patients with posttransfusion hepatitis of unknown etiology and is thought to be a new hepatitis virus. We determined the extent of TTV infection in the Japanese general population and the relationship between TTV DNA genotype and liver damage. In 1998, we tested 847 serum samples for TTV. TTV DNA was assayed by a nested polymerase chain reaction and classified into three different genotypes and eight subtypes. TTV DNA was detected in 25.3% and 32.4% of the inhabitants of the two areas studied, respectively. The genotype distribution was similar in both areas. G1, G2, and G3 were 60%, 20%, and 5%, respectively. Of the 20 subjects with TTV DNA alone and elevated serum ALT levels, 18 were G1, one was G2, and one was G3. TTV infection is endemic in the Japanese general population studied. The main TTV genotype, G1, may be related to the ensuing liver damage.

Hepatitis C virus carriers with persistently normal aminotransferase levels: healthy people or true patients?

Since the discovery of hepatitis C virus, the availability of serological hepatitis C virus screening has led to the identification of many subjects with normal aminotransferase levels who are chronically infected by the hepatitis C virus. To date, the epidemiology and natural history of subjects with normal aminotransferase levels are far from being clarified. Further, whether subjects with persistently normal aminotransferase levels should routinely undergo liver biopsy is still extremely controversial, and benefit from interferon treatment in this group of patients is yet to be proven. On account of the consistent normality of aminotransferases, it is not easy to calculate the rate of persons with normal aminotransferase levels among chronic hepatitis C virus carriers, nor their prevalence in the general population. It has been estimated that up to 25% of patients with chronic hepatitis C virus infection have persistently normal aminotransferase levels (10% to 40%, according to different studies). Most studies showed a clear prevalence of females, ranging from 58% to 90%. Liver biopsy shows some degree of chronic liver disease in up to 80% of these subjects, although in the majority, histological damage is mild and probably does not progress to more severe liver disease, moreover, the progression to fibrosis is slower than in patients with elevated aminotransferase levels. Virological features of these subjects (hepatitis C virus genotype distribution, viral load, quasispecies diversity) do not differ with respect to patients with elevated aminotransferase levels although a higher frequency of non 1 hepatitis C virus types has been reported. To date, no biochemical or virological tools to assess the presence and severity of liver damage exist. Antiviral treatment with interferon may induce a long-term response in only a small proportion of hepatitis C virus carriers with persistently normal aminotransferase levels, and many patients develop aminotransferase-flare-up during or shortly after treatment. Thus, interferon or combination antiviral treatment of hepatitis C virus carriers with normal aminotransferase values should be avoided in clinical practice.

Hepatitis C

In the latter half of the 20th century, HCV emerged as the most common cause of chronic liver disease, and will likely remain so. Since its initial discovery in 1989, rapid progress has been made in our understanding of the virology, epidemiology, natural history, diagnosis, and treatment of HCV. Over the next few decades, as further advancements are made, superior treatment options will become available.