Predicting interferon therapy efficacy from hepatitis C virus genotype and RNA titer

Treatment progress and expansion in Japan: From interferon to direct-acting antiviral

Hepatitis C virus (HCV) was first discovered in 1989, and patients infected with HCV were initially treated with interferon (IFN) monotherapy. In the 2000s, pegylated IFN combined with ribavirin was the mainstay of therapy for infected patients, but the sustained virologic response (SVR) rate was less than 50% for patients with HCV genotype 1. To further improve the therapeutic effect, direct-acting antiviral (DAA) was developed, and combination therapy with DAA and IFN has been available since 2011. In addition, IFN-free DAA therapy became available in 2014, and SVR was achieved in more than 95% of patients with chronic hepatitis and compensated cirrhosis. Thus, in just 30 years since the discovery of HCV, we aim to eliminate HCV in almost all patients. However, there are remaining issues to be addressed. Many of the patients who achieved SVR with DAA therapy had advanced liver fibrosis, and it is necessary to verify to what extent DAA therapy improves their prognosis in terms of liver function, hepatocellular carcinoma occurrence, and mortality. Resistance-associated substitutions can cause failure of DAA therapy, and the search for an effective therapy for high-level resistant viruses such as P32 deletion is particularly important. DAA therapy was approved for use in patients with decompensated cirrhosis in Japan in 2019, which is an unmet need so far. It is also important to verify the efficacy and safety in real-world settings. The World Health Organization aims to eliminate HCV by 2030, and Japan must tackle its remaining issues to achieve this goal.

Features of hepatitis C virus infection, current therapies and ongoing clinical trials in ten Asian Pacific countries

Estimated hepatitis C virus (HCV) infection rates in the general populations were 1.3, 0.9, 0.4-1.0, 14.7, 0.1-0.3, 0.9-1.9, 1.0-2.0, 5, 4.4-8.6 and 0.5-1.3 % in Australia, Bangladesh, Mainland China, Egypt, Hong Kong, India, Japan, Pakistan, Taiwan and Turkey, respectively. The main HCV genotypes (Gs) are G1, G3, G1b, G4, G1b, G3, G1b, G3, G1b and G2, and G1 in Australia, Bangladesh, Mainland China, Egypt, Hong Kong, India, Japan, Pakistan, Taiwan and Turkey, respectively. Of IL28B genotypes, favorable alleles are ~50 % in Australia and Turkey, but 60-70 % in most of the other Asian countries. Peginterferon plus ribavirin is available in all ten Asian Pasific countries. In addition, HCV NS3/4A protease inhibitors with peginterferon plus ribavirin are currently available in several countries. Clinical trials of interferon-free regimens for HCV are ongoing in most of the ten Asian Pacific countries.

Prevalence of hepatitis C virus infections and distribution of hepatitis C virus genotypes among Korean blood donors

BACKGROUND

Hepatitis C virus (HCV) remains a worldwide health-care burden. Prevalence rates vary and the distribution of genotypes depends on geographical location. Here, the recent prevalence of HCV infections and distribution of HCV genotypes among Korean blood donors were studied.

METHODS

Between February 2005 and December 2009, a total of 11,064,532 donors were screened for anti-HCV and 11,412,690 donors were screened for HCV RNA. HCV genotyping was conducted for 748 blood donors with HCV RNA by using the line probe assay (VERSANT HCV Genotype 2.0 Assay, Bayer Healthcare, USA) after amplification of the 5'-untranslated and core regions of the genome.

RESULTS

The anti-HCV prevalence was 0.16% (17,250/11,064,532). HCV RNA was detected in 959 out of the 11,412,690 donors (8.4/100,000). HCV RNA was more prevalent among women, donors who resided at harbor sites, and first-time donors. In addition, the prevalence of HCV RNA increased with age. The genotypes of 740 out of the 748 tested donors (98.9%) were identified. HCV genotype 1b (47.7%) and 2a/2c (35.0%) were dominant. Genotypes 2 (7.6%), 2b (2.3%), 3a (1.6%), 1a (1.3%), 1 (0.9%), 2v (0.5%), 1v (0.1%), and 3 (0.1%) were also identified. Genotype 4a/4c/4d (0.1%) was detected for the first time in one Korean blood donor.

CONCLUSIONS

The distribution of HCV genotypes in Korea has not changed remarkably, with the exception of genotype 4a/4c/4d. A periodic study to monitor the prevalence of HCV infections and the distribution of HCV genotypes is required to identify emerging genotypes in Korea.

Oxidative stress, endogenous antioxidants, alcohol, and hepatitis C: pathogenic interactions and therapeutic considerations

Hepatitis C virus (HCV) is a blood-borne pathogen that was identified as an etiologic agent of non-A, non-B hepatitis in 1989. HCV is estimated to have infected at least 170 million people worldwide. The majority of patients infected with HCV do not clear the virus and become chronically infected, and chronic HCV infection increases the risk for hepatic steatosis, cirrhosis, and hepatocellular carcinoma. HCV induces oxidative/nitrosative stress from multiple sources, including inducible nitric oxide synthase, the mitochondrial electron transport chain, hepatocyte NAD(P)H oxidases, and inflammation, while decreasing glutathione. The cumulative oxidative burden is likely to promote both hepatic and extrahepatic conditions precipitated by HCV through a combination of local and more distal effects of reactive species, and clinical, animal, and in vitro studies strongly point to a role of oxidative/nitrosative stress in HCV-induced pathogenesis. Oxidative stress and hepatopathogenesis induced by HCV are exacerbated by even low doses of alcohol. Alcohol and reactive species may have other effects on hepatitis C patients such as modulation of the host immune system, viral replication, and positive selection of HCV sequence variants that contribute to antiviral resistance. This review summarizes the current understanding of redox interactions of HCV, outlining key experimental findings, directions for future research, and potential applications to therapy.

Potent induction therapy with interferon and ribavirin combination therapy does not achieve a higher sustained virological response rate in chronic hepatitis C with genotype 1b and high hepatitis C virus RNA level

AIMS

To compare twice-daily interferon (IFN)-beta administration and once-daily IFN-alpha-2b administration as induction therapy in ribavirin combination therapy in chronic hepatitis C with a high viral load of genotype-1b hepatitis C virus (HCV).

METHODS

Sixty-one chronic hepatitis patients with a high viral load of genotype-1b HCV were randomly divided into three groups: group A was given IFN-beta 6 MU induction therapy twice daily for 2 weeks; group B was given IFN-alpha-2b 6 MU induction therapy once daily for 2 weeks; and group C was given no induction therapy. All three groups were then given IFN-alpha-2b 6 MU 3 days/week for the rest of the 24-week study period. Ribavirin was given for the entire 24-week study period.

RESULTS

Although the cumulative HCV-RNA negative rates tended to be higher in group A than in group B, the differencewas not significant. The HCV-RNA negative rate at week 2 was significantly higher in groups A and B than in group C (P < 0.05). The sustained virological response (SVR) rate was 16% overall, 21% for groups A and B, and 5% for group C; the SVR rate of groups A plus B tended to be higher than that of group C (P = 0.093).

CONCLUSIONS

There was no difference between the effects of the two induction therapies; potent induction therapy does achieve higher early viral clearance but not a higher SVR rate.

Antiviral therapy for chronic hepatitis C: past, present, and future

Antiviral therapy for chronic hepatitis C has dramatically advanced since the discovery of the hepatitis C virus (HCV) in 1989 and the introduction of interferon (IFN) monotherapy in the early 1990s. The current standard therapy uses a combination of pegylated IFN and ribavirin. The duration of therapy and response to therapy are HCV genotype-specific. Genotype 1 patients require 48 weeks of the combination therapy for 50% successful viral elimination, while genotype 2 patients require 24 weeks of therapy for 80% or 90% viral elimination. Early viral kinetics after the initiation of therapy is a useful predictor of the sustained virologic response (SVR), which is formally determined at 24 weeks after completion of the treatment. For example, an early virologic response, which is determined by a 2-log reduction of HCV RNA or viral elimination at 12 weeks after the initiation of therapy, is a strong negative predictor of SVR in genotype 1 patients. In contrast, a rapid virologic response of HCV RNA-negative at 4 weeks after the initiation of therapy identifies genotype 2 "super-responders," who may require a shorter period of therapy. Adherence to therapy is one of the most important factors for successful viral clearance. Hematopoietic growth factors such as epoetin and granulocyte-colony stimulating factor help reduce therapy-mediated cytopenia and improve patient compliance, thereby leading to better viral clearance. New types of anti-HCV agents such as HCV protease and polymerase inhibitors are needed for those patients that do not respond to combination therapy.

Sequence elements correlating with circulating viral load in genotype 1b hepatitis C virus infection

The correlation between hepatitis C virus (HCV) genomic sequences and circulating HCV RNA levels was assessed to investigate the genetic elements affecting viral load. The interferon sensitivity-determining region (ISDR) sequence and the serum viral load were strongly correlated in 226 patients examined. Analysis of the entire HCV genome from six patients (three with a high and the others with a low viral load) with similar ISDR sequences identified several candidate residues associated with viral load. The amino acid (aa) sequences of these candidate residues and flanking regions in 67 additional patients revealed that only the residue at aa 962 varied significantly between the HCV patients with low and high serum loads (P=0.042). At this position, alanine was observed more frequently in the patients with a high viral load. In conclusion, our results strongly suggest that serum HCV RNA loads are inversely correlated with amino acid substitutions in the ISDR, and aa 962 was identified as a possible second determinant of serum HCV RNA load.

Sequence analysis of PePHD within HCV E2 region and correlation with resistance of interferon therapy in Japanese patients infected with HCV genotypes 2a and 2b

OBJECTIVE

Hepatitis C virus (HCV) E2 protein was recently reported to have a double-stranded RNA-activated protein kinase-eukaryotic initiation factor 2alpha (PKR-eIF2alpha) phosphorylation homology domain (PePHD); PKR is induced by interferon (IFN). PePHD interacts with PKR and inactivates it. PePHD could be a predictor for IFN response, like the interferon sensitivity determination region (ISDR) of HCV NS5A. Several groups reported that PePHD is conserved, and mutations in this region do not correlate with IFN response. In this study, we further investigated the amino acid variation of PePHD among four major genotypes and its correlation with IFN response.

METHODS

We enrolled 74 patients for this study and determined PePHD sequence of HCV derived from sera of patients infected with HCV genotype 1a (1 patient; nonresponder [NR]), 1b (36 patients; 4 complete responders [CR], 32 NR), 2a (29 patients; 17 CR, 12 NR), and 2b (8 patients; 3 CR, 5 NR). We also analyzed mutations in ISDR of HCV genotype 1b in 31 patients.

RESULTS

PePHD had several variations among four genotypes investigated. In patients infected with HCV genotype 1b, PePHD sequence was well conserved and seemed to have no correlation with IFN response. Mutations in ISDR were correlated with IFN response. In patients with HCV genotypes 2a and 2b, PePHD had multiple variations, and one particular motif, "RGQQ-" at the N-terminus, showed a close correlation with IFN resistance. All eight patients with HCV containing this motif were IFN nonresponders.

CONCLUSIONS

IFN resistance of HCV correlates with its "RGQQ-" motif at the N-terminus of PePHD in HCV genotype 2a and 2b. PePHD of HCV could be a predictor of IFN resistance in patients infected with HCV genotype 2a and 2b.

Efficacy of interferon-alpha treatment in Japanese children with chronic hepatitis C

BACKGROUND

We investigated the efficacy of natural interferon (IFN)-alpha treatment in 34 Japanese children with chronic hepatitis C.

METHODS

Thirty-four children completed 6 months of therapy with natural IFN-alpha and were followed for 12 months or longer. We examined the serum hepatitis C virus (HCV) RNA titer and liver histology before, during, and after IFN treatment.

RESULTS

At 6 months after the cessation of IFN-alpha treatment, 16 patients (47%) had normal serum alanine aminotransferase concentration and no detectable serum HCV RNA. There were no major side-effects, excluding some influenza-like symptoms during the IFN-alpha treatment. Most genotype 2a patients had a complete response (80%). Moreover, patients who had a low HCV RNA titer (<102 copies/mL) after 1 month of IFN-alpha treatment became complete responders at 6 months after the cessation of treatment. Histological improvement was observed in almost all patients after IFN-alpha treatment.

CONCLUSION

Interferon-alpha treatment is safe and effective for children with chronic hepatitis C and has no serious side-effects. A HCV RNA concentration of <102 copies/mL after 1 month of IFN-alpha treatment and genotype 2a may be useful predictors of long-term IFN efficacy.

Nonimmune complexed HCV RNA titer in serum as a predictor of interferon response in patients with chronic hepatitis C

OBJECTIVE

Hepatitis C virus (HCV) has been reported to exist in the circulation of patients in various forms such as free virions, immune complexes, and nucleocapsids. To clarify the clinical significance of serum HCV titers according to the forms of virus particles, we evaluated the immune complexed (IC) and nonimmune complexed (NIC) HCV RNA titers in 77 chronic hepatitis patients treated with interferon (IFN).

METHODS

IC and NIC forms in pretreatment serum were separated by immunoprecipitation using antihuman immunoglobulin antibody, and quantified by reverse transcription polymerase chain reaction.

RESULTS

Serum titers of NIC HCV RNA were correlated with those of whole serum HCV RNA (r = 0.96, p < 0.01) and IC HCV RNA (r = 0.98, p < 0.01), but they were not with the aminotransferase levels, gamma-globulin concentration, and grading or staging of liver histology. Nonresponders to IFN had significantly high NIC HCV RNA titers compared with sustained responders (10(4.93 +/- 0.81) copies/ml vs 10(4.06 +/- 0.69) copies/ml, p < 0.01). It is noteworthy that the relative amount of NIC HCV RNA to whole serum HCV RNA was also significantly higher in nonresponders than in sustained responders (0.66 +/- 0.10 vs 0.50 +/- 0.11, p < 0.0001). Multivariate analysis showed that low NIC HCV RNA titer (p < 0.01) and genotype 2 (p = 0.02) were independent variables contributing to sustained response to IFN, but the whole serum HCV RNA titer was not.

CONCLUSIONS

Pretreatment NIC HCV RNA titer is a more reliable predictive marker than genotype or whole serum HCV RNA of a sustained response to IFN monotherapy. This finding suggests that humoral immunity may affect the response to IFN.

Dynamic changes of HVR1 quasispecies in chronic hepatitis C after IFN therapy

AIM: To evaluate the correlation between the complexity of HCV HVR1 quasi-species and their response to IFN therapy in patients with chronic hepatitis C.

METHODS: Twenty patients with chronic hepatitis C received IFN therapy (3 mu/d, three times/week for 24 wk). Serum quasispecies complexity of HVR1 was analyzed by polymerase chain reaction mediated singl-strand conformation polymorphism (SSCP) before and 3 mo, 6 mo post-therapy, respectively.

RESULTS: Of 20 patients, 7 had low level of complexity (SSCP bands ≤ 3), 13 had high level of complexity (SSCP bands > 3). The rate of HCV RNA negative in low level complexity group was higher than that in high level complexity group. Patients with low level of complexity prior to therapy had good responsive to IFN; Serum HCV RNA in some patients did not convert to negative after IFN therapy, however, the number of SSCP bands decreased gradually.

CONCLUSION: HCV HVR1 quasi-species complexity is a predictive factor in response to IFN therapy, a statistically significant correlation between high level of complexity of HCV HVR1 quasi-species and lacking of response to IFN therapy in patients with chronic hepatitis C was found.

To interfere and to anti-interfere: the interplay between hepatitis C virus and interferon

As popular strategies used by numerous viruses, interception of interferon (IFN) signaling and inhibition of IFN-induced antiviral functions allow viruses to evade the host immune response and set up successful infections. Hepatitis C virus (HCV), the leading cause of chronic liver disease worldwide and a major public health hazard, causes persistent infection in the majority of infected individuals. IFN-based therapies, currently the only ones available for HCV infection, have been unable to eliminate viral infection in the majority of patients, and many studies suggest that HCV possesses mechanisms to antagonize the IFN-induced antiviral response. Multiple viral, host, and IFN-associated factors have been implicated in the interplay between HCV and IFN. Two viral proteins, NS5A and E2, became the focus of much attention and extensive study because of their abilities to inhibit IFN-induced, double-stranded RNA-activated protein kinase (PKR), a major mediator of the IFN-induced biologic response, and to perturb the IFN signaling pathway. In this review, we discuss the significance of the interferon sensitivity determining region (ISDR) within NS5A, which has been the subject of intense debates. In addition, we discuss the potential mechanisms by which NS5A interferes with IFN signaling and the current working models. Further understanding of the molecular mechanisms underlying the interaction between HCV and IFN will likely facilitate improvement of current IFN-based therapies and development of novel treatments for the HCV pandemic. Future HCV research will benefit from both the development of efficient, convenient model systems for viral propagation, and the utilization of high throughput, genomic-scale approaches.

Alcohol abstinence does not offset the strong negative effect of lifetime alcohol consumption on the outcome of interferon therapy

Heavy alcohol consumption has been reported to negatively affect the outcome of interferon therapy. We studied the impact of lifetime alcohol consumption in patients with chronic hepatitis C treated with interferon after 6 months of alcohol withdrawal. Alcohol intake was measured when patients with chronic hepatitis C were referred to us for the first time, and from that moment complete abstinence was recommended. After 6 months of abstinence, 150 patients with persistent elevated serum alanine aminotransferase (ALT) have been treated with interferon (IFN)-alpha, 3 or 6 microU three times per week for 12 months. Univariate and multivariate analysis were performed to identify the predictors of treatment response. Carbohydrate-deficient transferrin was employed to assess alcoholic abstinence. The sustained response rate felt from 33% in nondrinkers to 20% of mild-drinkers and to only 9% in heavy drinkers. Drinker patients showed a relapse rate twice as high as that of nondrinkers. According to the multivariate analysis, the strongest independent predictors of nonresponse were genotype 1b infection, age of the patients and their lifetime alcohol intake. Carbohydrate-deficient transferrin detected at baseline, at 3 months of therapy and at the end of follow-up gave a positive result only in eight determinations (1.77%), confirming the compliance of patients to our recommendation of alcohol abstinence. Lifetime alcohol consumption has a strong negative effect on the outcome of interferon treatment, mainly in heavy drinkers. A 6-month period of abstinence may not be sufficient to offset this negative effect on treatment outcome.

Amino acid substitutions in the nonstructural region 5A of hepatitis C virus genotypes 2a and 2b and its relation to viral load and response to interferon

OBJECTIVES

The interferon sensitivity-determining region (ISDR) in nonstructural region 5A (NS5A) of hepatitis C virus genotype 1b has been reported to correlate with response to interferon therapy and viral load. Recently the correlation between NS5A and response to interferon in genotype 2a was also reported. We examined the region of genotypes 2a and 2b corresponding to the ISDR of genotype lb to elucidate its correlation with response to interferon and viral load.

METHODS

The sequences of amino acid positions 2213-2248 in NS5A were determined in 39 patients with genotype 2a and 12 patients with genotype 2b.

RESULTS

In the patients infected with genotype 2a, the number of amino acid substitutions in the ISDR-corresponding region compared with the consensus sequence of genotype 2a was significantly correlated with viral load (p = -0.541, p < 0.001) and with response to interferon therapy (p < 0.05); 83% of the patients with three or more substitutions obtained sustained responses, whereas only 44% of those with less than three substitutions obtained sustained responses. Multivariate analysis confirmed that the number of substitutions in the ISDR-corresponding region of genotype 2a was one of the independent predictors of response to interferon therapy (discriminant coefficient = 1.35, p < 0.001).

CONCLUSIONS

Substitutions in the ISDR-corresponding region in NS5A of hepatitis C virus genotype 2a was confirmed to correlate to viral load and response to interferon therapy. In genotype 2b, further work must be considered because of the small number of patients studied.

Ethnicity and cytokine production gauge response of patients with hepatitis C to interferon-alpha therapy

Interferon is the primary treatment for hepatitis C virus (HCV). However, the long-term success rate is low particularly for African Americans relative to Caucasians and may be due to differential immune abilities. This study compared cytokine production from PHA-stimulated peripheral blood from 25 healthy and 40 HCV-infected African Americans and Caucasians. HCV patients were designated as IFN responders or nonresponders based on outcome after therapy. Ethnicity and genotype were associated with IFN response. IFN responders were 100% Caucasian, whereas nonresponders were 67% Caucasian and 33% African American (P = 0.01). Genotype 1 was present in 100% nonresponders and 50% responders (P < 0.05). Age, sex, liver histology, ALT, and viral titers were equivalent (ns). Cytokine production from healthy individuals showed ethnic variation in cytokine levels. Healthy African Americans produced greater amounts of IL-2 (P = 0.06), TNF-alpha (P = 0.06) and less IL-10 (P = 0.05) than healthy Caucasians. In contrast, IFN-gamma and TGF-beta levels were equivalent. Pretherapy cytokine production among HCV patients showed a similar pattern of ethnic variation. African American nonresponders produced more IL-2 (P = 0.06) and TNF-alpha (P = 0.02) than Caucasian nonresponders. Cytokine levels among Caucasian and African American nonresponders were equivalent (P = ns) to ethnically matched healthy individuals whereas Caucasian responders produced subnormal levels of IL-10 (P < 0.05) and TGF-beta (P < 0.05). Since all African Americans failed IFN therapy, cytokine production could not be compared with therapeutic outcome. However, comparison of cytokine production among Caucasians showed that responders produced less IL-10 (P < 0.001) and more TGF-beta (P = 0.06) than nonresponders and predicted Caucasian nonresponders with 83% sensitivity and 96% specificity. HCV genotype was not relevant to cytokine production (P = ns). Distribution of cytokine genetic polymorphisms (TNF-alpha, TNF-beta, IL-10, TGF-beta) was equivalent in all ethnic groups and did not predict clinical nonresponders. In summary, it appears that ethnicity may contribute to variable immune responses and therapeutic outcome. The cytokine profile among African Americans suggests a more robust immune response, which may complicate therapy with IFN. In contrast, the subnormal cytokine production among Caucasian responders may be more permissive to IFN therapy. Pretherapy cytokine production may allow prediction of drug resistance among Caucasians.

Significance of serum soluble Fas antigen level in chronic hepatitis C patients treated with interferon: relationship to the therapeutic response

BACKGROUND AND AIM

Fas system-mediated cytotoxicity is thought to be involved in the development of liver injury in hepatitis C virus (HCV) infection. In this study, we investigated serum soluble Fas antigen levels in chronic hepatitis C patients treated with interferon and their correlation with the therapeutic response.

METHODS

The subjects were 67 chronic hepatitis C patients who underwent a 24-week course of alpha-interferon therapy. Patients were categorized into three groups; sustained responders (n = 22), transient responders (n = 24), and non-responders (n = 21), according to changes in the serum alanine aminotransferase level during and after therapy. The viral genotype, viremic level and diversity in the hypervariable region were examined before therapy. Serum soluble Fas antigen levels were assayed by using serum samples taken at the beginning and the end of therapy.

RESULTS

In the univariate analysis, serum soluble Fas antigen levels tended to be higher in non-responders (10.0 +/- 3.4 ng/mL) than in sustained responders (8.5 +/- 3.0 ng/mL) and transient responders (8.2 +/- 2.1 ng/mL; P = 0.13 and P < 0.05). The non-response to therapy was observed in eight of the 15 (53%) patients with serum soluble Fas antigen > or = 11 ng/mL, compared with 13 of the 52 (25%) patients with serum soluble Fas antigen < 11 ng/mL (P < 0.05). As for the multivariate analysis, the only significant factor contributing to the sustained response was a low HCV viremic level (P = 0.0046). Significant factors contributing to the non-response were a high serum alanine aminotransferase (P = 0.0407) and a high serum soluble Fas antigen level (P = 0.0483).

CONCLUSIONS

High production levels of soluble Fas antigen may be associated with a poor response to interferon therapy in chronic hepatitis C patients.

Long-term histological prognosis and serum fibrosis markers in chronic hepatitis C patients treated with interferon

BACKGROUND

Interferon (IFN) therapy is effective in 20-40% of patients with chronic hepatitis C, but the relationship between histological changes and the response to interferon is still unclear. We investigated the long-term histological prognosis and the changes of serum fibrosis markers after interferon therapy relation to the response.

METHODS AND RESULTS

One hundred and eighteen patients with chronic hepatitis C who received interferon therapy were divided into four groups based on the detection of viremia and the serum alanine aminotransferase (ALT) level after treatment. A histological examination was performed by using the histological activity index and the criteria of the METAVIR score. Serum fibrosis markers were used to measure the levels of hyaluronic acid and type IV collagen 7s. Responders, whose serum ALT levels became normal after treatment, demonstrated histological improvement. Histological improvement was more rapid in sustained virological responders with hepatitis C virus (HCV) RNA seronegativity than in biochemical responders with HCV-RNA seropositivity. Only sustained virological responders exhibited histological cure. In partial responders, whose serum ALT levels decreased to less than twice the upper of normal, and non-responders whose serum ALT levels were not reduced, liver fibrosis was unchanged or showed progression. Serum fibrosis markers increased with progression of the histological stage and varied depending on the response to interferon.

CONCLUSION

Normalization of serum ALT levels after interferon therapy led to a histological improvement, and that with viral clearance achieved histological cure. Serum fibrosis markers were useful indicators for long-term according to the response of IFN therapy.

Decline of hepatitis C virus load in serum during the first 24 h after administration of interferon-beta as a predictor of the efficacy of therapy

BACKGROUND/AIMS

Hepatitis C virus (HCV) kinetics during interferon (IFN)-alpha treatment have been evaluated recently, however, little is known about the resultant viral kinetics in IFN-beta treatment. In this study, we evaluated HCV kinetics during the first 24 h of IFN-beta treatment, and also assessed their relationship to therapeutic outcomes.

METHODS

We measured HCV RNA levels at 0 and 24 h after the initiation of IFN-beta treatment, and we calculated the decay slope, viral half-life, and viral production and clearance. Then we analyzed these factors as they related to therapeutic responses with IFN-beta as well as to clinical variables, i.e. genotype, diversity of hyper variable region, and histological findings.

RESULTS

Patients with sustained responses (SR) displayed steeper decay slopes of the viral load than those without SR (2.87 +/- 1.41 vs. 1.82 +/- 1.66, P = 0.031). On the other hand, the decay slope was not affected by the clinical variables. The values of viral half-life and viral production and clearance showed no significant correlation to the response and the clinical variables.

CONCLUSION

This study demonstrated that the decay slope of the viral load during the first 24 h is related to the virological response to IFN-beta treatment.

Low cell binding ability of HCV is closely related to interferon treatment especially in patients with HCV genotype 2a/2b. A large series prospective study on Japanese patients with chronic hepatitis C

BACKGROUND/AIMS

We have previously shown that the quantity of antibody-free virion in the pre-treatment sera of the patients with chronic hepatitis C is a good predictive factor for the efficacy of interferon treatment. However, the biological significance of the free virion should be verified by a prospective study.

METHODS

We prospectively evaluated 152 consecutive patients with chronic hepatitis C who received a standardized interferon treatment, and analyzed the free virion and the binding titers, the ability of hepatitis C virus (HCV) to bind to the human lymphocytic cell line.

RESULTS

Sixty-five patients achieved a long-term sustained remission, 76 patients did not respond to the interferon therapy, and 11 patients dropped out. The sera from the patients with genotype 2a/2b had significantly lower free virion and cell binding titers than those with genotype 1b. A multivariate analysis showed three independent variables associated with the interferon response; cell binding titer <10(0.5)/ml, viral load <10(4.5) copies/50 microl, and genotype 2a/2b with odds ratios of 14.6, 11.8, and 9.8, respectively.

CONCLUSIONS

The low level of in vitro cell binding ability of HCV helped to clarify the good responsiveness to interferon observed in patients especially with a high viral load of genotype 2a/2b.

Hepatitis C virus and interferon resistance

Interferon plays a critical role in the host's natural defense against viral infections and in their treatment. It is the only therapy for hepatitis C virus (HCV) infection; however, many virus isolates are resistant. Several HCV proteins have been shown to possess properties that enable the virus to evade the interferon-mediated cellular antiviral responses.

Genetic changes in the interferon sensitivity determining region of hepatitis C virus during the natural course of chronic hepatitis C

Amino acid mutations in the interferon sensitivity determining region (ISDR) are closely associated with the response to interferon in patients with hepatitis C virus genotype 1b (HCV-1b) infection. In this study, 36 patients chronically infected with HCV-1b, with no history of interferon therapy with respect to ISDR changes in HCV were studied. Two serum samples were obtained from each patient, with an average interval of 3.5 years, and predominant nucleotide and amino acid sequences of the ISDR at initial and subsequent time points were compared for each patient. Three of 12 patients with the wild type ISDR (no amino acid mutation in the ISDR compared to the consensus sequence) changed to the intermediate type (1 to 3 mutations) at later time points, whereas the other 9 still had the wild type. Similarly, 2 of 18 patients with the intermediate type changed to the wild type, whereas the other 16 patients continued to have the intermediate type. One of 6 patients with the mutant type (4 or more mutations) changed to the intermediate type, and the other 5 continued to have the mutant type. Although ISDR nucleotide changes/site/year were not significantly different among the 3 groups of patients, percentages of non-synonymous nucleotide changes were greater in the mutant type (63%) than the wild (9%) or the intermediate type (20%) (P < 0.05). These results show that mutations in the ISDR do not occur frequently, suggesting that interferon sensitivity does not change greatly during the natural course of the disease in each patient.

Hepatitis C virus quantitation: optimization of strategies for detecting low-level viremia

A long-term assessment of quantitative hepatitis C virus (HCV) testing was performed at the University of Pittsburgh Medical Center. The Quantiplex HCV RNA 2.0 branched-chain DNA (bDNA) assay (Bayer Diagnostics) for hepatitis C viral load determination was used to test 3,471 specimens. bDNA-negative samples were also tested by an in-house qualitative reverse transcriptase (RT)-PCR assay with a measured sensitivity of fewer than 100 HCV genome equivalents per milliliter. Of 1,239 bDNA-negative specimens, 74.1% were negative and 25.9% were positive by RT-PCR, indicating the presence of viremia in a significant proportion of bDNA-negative samples. We discuss the medical and economic implications of these results and propose two alternatives for clinical laboratories to consider in approaching quantitative HCV testing. For laboratories able to perform a sensitive RT-PCR assay for </=40% of the bDNA test cost, prescreening bDNA requests by RT-PCR may be the most cost-effective approach.

Clinical significance of hepatitis C virus genotypes

The advent of genotyping assays has stimulated investigators around the world to study the molecular epidemiology of hepatitis C virus (HCV) infection in specific patient categories, as well as possible correlations with the clinical and histological features of chronic liver disease and response to antiviral treatment. While a general consensus has been reached on the worldwide epidemiology and distribution of HCV types in certain risk categories (i.e. intravenous drug users), the association between genotype 1b and severe liver disease is still controversial. Although generalized use of genotyping is not presently recommended for clinical or epidemiological monitoring, several studies emphasize to the importance of HCV genotyping as part of a therapeutic algorithm. This recommendation is based on overwhelming evidence in support of a correlation between genotype 1 and a poor response to interferon-a alone or in combination with ribavirin.

[Characteristics of the hepatitis C virus and viral predictors of therapeutic response]

NATURAL HISTORY OF HEPATITIS C-INFECTION AND VIRAL CHARACTERISTICS: Hepatitis C-virus (HCV) infection is a major cause of non-A, non-B-hepatitis and, additionally, is associated with liver cirrhosis and hepato-cellular carcinoma. The high degree of chronificity of HCV-infection is reasonable due to antigenic variability of neutralizing epitopes leading to incomplete immunoresponse with subsequent virus persistence. Besides genetic variants of HCV within a virus population (quasispecies nature of HCV), different genotypes are classified being genetically and phenotypically distinct, and geographically restricted in part. Genotyping of HCV is not only important for phylogenetic and epidemiological studies, but also a predictive marker for pathogenesis and therapy. VIRAL PREDICTORS OF HCV THERAPY: In a meta-analysis of 18 therapeutical studies of chronical HCV infections, genotype 1 and high levels of viremia determined markedly the response to interferon therapy. In this context, clinical trials have proven the effect of a combined therapy with interferon and ribavirin. Especially patients with HCV genotype 1 or high levels of viremia had a real benefit from combined antiviral therapy in comparison to monotherapy with interferon. CONCLUSION AND FUTURE CONCEPTS: Besides recent concepts improving the therapeutical response to HCV infection, further effort is necessary to develop more successful strategies for eradication of hepatitis C virus. In this context, variations of interferon therapy should be evaluated (e.g. higher and daily doses, longer duration of interferon therapy, "retarded" interferon (PEG-IFN). In addition, new therapeutical concepts should be performed including a combination of interferon with other known antiviral agents (amantadine), a combination with immunomodulators (GM-CSF, thymosin alpha 1), the development of new antiviral agents (inhibitors of viral proteases, helicases and polymerases) and the exploration of anti-viral, molecular strategies (specific ribozymes, antisense oligonucleotides and DNA-vaccination). Nevertheless, the development of an effective vaccination should be the most important challenge for the future.

Influence of transfusion-transmitted virus infection on the clinical features and response to interferon therapy in Japanese patients with chronic hepatitis C

Recently, the genome of a novel DNA virus, transfusion-transmitted virus (TTV), was cloned from the plasma of a blood donor who had an elevated aminotransferase level but no serological markers of known hepatitis viruses. In this study, we investigated the influence of TTV infection on the clinical features and response to interferon (IFN) therapy in patients with chronic hepatitis C. We studied 247 patients who had received a 16- or a 24-week course of IFN-alpha therapy. The serum of these patients was analysed for TTV DNA using a hemi-nested polymerase chain reaction and TTV was detected in 114 patients (46%). No significant differences were found with respect to clinical features (gender, age, liver-related biochemical tests, hepatitis C virus (HCV) genotype and serum HCV RNA levels) between the patients who were positive for TTV DNA and those who were negative for TTV DNA. The fibrosis score was higher in TTV-positive patients (2.1 +/- 1.1) than in TTV-negative patients (1.7 +/- 1.1, P = 0.023). The biochemical sustained-response rate was 25% in TTV-positive patients and 25% in TTV-negative patients (not significant). A sustained HCV clearance rate was achieved in 26% of TTV-positive patients and in 22% of TTV-negative patients (not significant). TTV DNA clearance after IFN therapy was observed in 36 of 69 patients (52%) for whom stored serum samples were available. The disappearance of TTV DNA had no effect on the biochemical response to IFN therapy. In conclusion, TTV co-infection is frequently observed in Japanese patients with chronic hepatitis C. In chronic hepatitis C, TTV does not modify the clinical features or the response to IFN.

Selection of genetic variants of the 5' noncoding region of hepatitis C virus occurs only in patients responding to interferon alpha therapy

Interferon alpha (IFN alpha) can suppress the replication of hepatitis C virus (HCV) in chronically infected patients. However, HCV persists in a significant number of patients despite the normalization of alanine transaminase (ALT) during IFN alpha therapy. In this study, HCV variants in patients under IFN alpha therapy were characterized to examine their role in viral persistence during the therapy. Sixteen patients selected for this study were infected with HCV genotype 1b and remained HCV RNA positive for at least 1 month after onset of therapy. Nine patients responded to the therapy in terms of normalization of ALT (responders), whereas seven patients did not show a significant decrease of ALT level (nonresponders). To examine HCV populations in these patients, the HCV 5' noncoding region (5' NCR) was analyzed by polymerase chain reaction amplification and sequencing. Newly emerging variants of the HCV 5' NCR replaced predominant variants present prior to IFN alpha therapy in six of nine responders. Most predominant HCV variants during IFN alpha therapy carried a nucleotide substitution G to A at nt 231 within the 5' NCR. An analysis of the HCV quasispecies population in one responder revealed that a preexisting variant became predominant under IFN alpha therapy. These results emphasized the importance of the genetic heterogeneity of the HCV genome for viral resistance to IFN alpha. Five of seven HCV isolates from nonresponders were identical to those found in responders with regard to the nucleotide sequence of the 5' NCR. However, no selection of variants of the HCV 5' NCR occurred in nonresponders during the course of therapy. We conclude that IFN alpha treatment leads to the selection of variants of the HCV 5' NCR only in responders and may act differently in nonresponders. Our results suggest that the HCV 5' NCR may be a target of anti-HCV actions of IFN alpha.

Mutations in nonstructural protein 5A gene and response to interferon in hepatitis C virus genotype 2 infection

An association has been reported between mutations in the amino acid residues 2209-2248 of the nonstructural protein 5A (NS5A) gene (interferon-sensitivity determining region [ISDR]) and interferon efficacy in hepatitis C virus (HCV)-1b infection. This relationship was analyzed in chronic HCV-2 infection. Forty patients with HCV-2a and 35 with HCV-2b were treated with interferon alfa for 6 months with a total dose of 468 to 860 million units. Pretreatment NS5A sequences were determined by direct sequencing. A higher complete and sustained response rate was observed in HCV-2a than in HCV-2b (70% vs. 34%; P =.003). Serum HCV-RNA levels were lower in complete responders than nonresponders in HCV-2a (P =.049) and HCV-2b (P =. 02). The number of amino acid mutations was greater in complete responders than nonresponders in NS5A2193-2228 (the region corresponding to the ISDR of HCV-1b) alone (P =.049), or NS5A2163-2228 consisting of NS5A2193-2228 plus its upstream region (P =.02) in HCV-2a, but not in HCV-2b. A significant inverse correlation was observed between serum HCV-RNA levels and the number of amino acid mutations in NS5A2193-2228 (P =.003) or NS5A2163-2228 (P =.005) in HCV-2a. With multivariate analysis, the number of substitutions in NS5A was an independent predictor for complete response in HCV-2a (odds ratio: 6.4; P =.03). Interferon efficacy is associated with amino acid variations in the NS5A protein in HCV-2a infection.

Apical hypertrophic cardiomyopathy and hepatitis C virus infection

The familial form of hypertrophic cardiomyopathy (HCM) is attributed to mutations in the genes for contractile proteins, but the etiology of non-familial form remains unknown. This study was designed to examine the clinical features, histopathologic changes, and hepatitis C virus (HCV) genomes in patients with HCM associated with HCV infection. Anti-HCV antibody was present in the sera of 9 of 65 patients (13.8%) with HCM versus 2.41% in a control population of voluntary blood donors in Japan, a statistically significant difference (p<0.0001). Among these 9 patients, 6 had ace-of-spades-shaped deformities of the left ventricle with apical hypertrophy. Myocardial fibrosis was found in all patients, and mild cellular infiltration was observed in 5 patients. Type 1b HCV RNA was present in the sera of 5 of the 9 patients. The copy number of HCV was 5.5x10(3)-8.6x10(5) genomes/ml serum, and multiple clones of HCV were detected in the sera of each patient by an analysis of the hypervariable regions using fluorescent single-strand conformation polymorphism. Positive strands of HCV were found in the hearts of 5 patients, and negative strands in the hearts of 2 patients. A high prevalence of HCV infection was found in patients with HCM, particularly of the apical variety, suggesting that HCV is an important causal agent in the pathogenesis of the disease.

Involvement of transporter associated with antigen processing 2 (TAP2) gene polymorphisms in hepatitis C virus infection

BACKGROUND & AIMS

Transporter associated with antigen processing (TAP) has essential roles in the antigen-presenting systems, translocating antigenic peptides from the cytosol into the endoplasmic reticulum. The aim of this study was to clarify whether TAP polymorphisms are involved in hepatitis C virus (HCV) infection.

METHODS

The 145 HCV-infected Japanese patients examined in this study were categorized into two groups: 36 carriers with persistently normal alanine transaminase (ALT) values and 109 patients with chronic liver disease (CLD). TAP2 gene phenotypes were determined by means of polymerase chain reaction-restriction fragment length polymorphism, and their frequencies were compared between the two groups.

RESULTS

Frequencies of TAP2*0101, *0102, and *0201 were not different between the two groups. However, TAP2*0103 frequency in carriers with normal ALT levels was significantly higher than that in patients with CLD (44% vs. 16%; P = 0.00064, Pc < 0.005). Although the TAP2*0103 allele was tightly linked with class II DRB1*1302-DQB1*0604 haplotype in this study, the TAP2*0103 frequency in the normal ALT group was also significantly higher than that in the CLD group even in DRB1*1302-DQB1*0604-negative patients (31% vs. 10%; P = 0.0076, Pc < 0.05).

CONCLUSIONS

These findings suggest that TAP2*0103 may be closely associated with low serum ALT activity in HCV-infected Japanese patients.

Characterization of the effects of hepatitis C virus nonstructural 5A protein expression in human cell lines and on interferon-sensitive virus replication

The hepatitis C virus (HCV) nonstructural 5A (NS5A) protein has been implicated in the inherent resistance of HCV to interferon (IFN) antiviral therapy in clinical studies. Biochemical studies have demonstrated that NS5A interacts in vitro with and inhibits the IFN-induced, RNA-dependent protein kinase, PKR, and that NS5A interacts with at least one other cellular kinase. The present study describes the establishment and characterization of various stable NS5A-expressing human cell lines, and the development of a cell culture-based assay for determining the inherent IFN resistance of clinical NS5A isolates. Human epithelioid (Hela) and osteosarcoma (U2-OS) cell lines were generated that express NS5A under tight regulation by the tetracycline-dependent promoter. Maximal expression of NS5A occurred at 48 hours following the removal of tetracycline from the culture medium. The half-life of NS5A in these cell lines was between 4 to 6 hours. NS5A protein expression was localized cytoplasmically, with a staining pattern consistent with the location of the Golgi apparatus and endoplasmic reticulum. In the majority of cell lines, no obvious phenotypic changes were observed. However, three genotype 1b NS5A-expressing osteosarcoma cell lines exhibited cytopathic effect and severely reduced proliferation as a result of high-level NS5A expression. Full-length NS5A protein isolated from a genotype 1b IFN-nonresponsive patient (NS5A-1b) was capable of rescuing encephalomyocardititis virus replication during IFN challenge up to 40-fold, whereas a full-length NS5A-1a and an interferon sensitivity determining region (ISDR) deletion mutant (NS5A-1a-triangle upISDR) isolated from a genotype 1a IFN-nonresponsive patient showed no rescue activity. The NS5A-1b and NS5A-1a proteins also rescued vesicular stomatitis virus replication during IFN treatment by two- to threefold. These data cummulatively suggest that NS5A expression alone can render cells partially resistant to the effects of IFN against IFN-sensitive viruses, and that in some systems, these effects may be independent of the putative ISDR. A scenario is discussed in which the NS5A protein may employ multiple strategies contributing to IFN resistance during HCV infection.

Interferon and thymosin combination therapy in naive patients with chronic hepatitis C: preliminary results

AIMS/BACKGROUND

This randomized study was performed to compare the efficacy of interferon-alpha (IFN-alpha) + thymosin alpha 1 (Talpha1) treatment to that of IFN-alpha alone in light of biochemical and virological response of naive patients with chronic hepatitis C.

METHODS

Seventeen patients were treated with IFN alpha-2b (3 million units MU three times a week) + Talpha1 (1 mg twice weekly); the other 17 patients received only IFN alpha-2b at the same dose. All patients were treated for 6 months and followed up for 12 months. Biochemical (ALT values) and virological (HCV-RNA) responses to treatment were determined.

RESULTS

Combination therapy showed significantly higher efficacy than monotherapy in achieving biochemical and virologic end-of-treatment response (p<0.05). At 12 month follow-up, the sustained biochemical response was slightly greater in patients treated with combination therapy than in those treated with monotherapy. No significant difference in response by HCV-1b subtype was observed between the two treatment groups; however, HCV-2c subtype showed a trend to responding better to IFN-alpha+Talpha1 than to IFN-alpha alone.

CONCLUSIONS

These data suggest that the immune modulator Talpha1 may be additive or synergistic with IFN-alpha in normalizing end-treatment biochemical and virological responses in patients with chronic hepatitis C. Higher doses and/or more prolonged courses may improve the sustained response rates to this treatment.

Mutations in the interferon-sensitivity determining region of hepatitis C virus and transcriptional activity of the nonstructural region 5A protein

Amino acid (aa) mutations in the interferon-sensitivity determining region (ISDR) (aa position 237-276 of the nonstructural region 5A [NS5A] protein consisting of 447 amino acids) of hepatitis C virus (HCV) are related to increased interferon sensitivity and low viral load, but its mechanism has not been clarified. Recently, the NS5A protein has been reported to have a transcriptional activation function, like other viral transactivator proteins known to repress interferon-induced gene expression, and the ISDR overlaps one of the acidic amino acid regions, putative domains conferring this activity. In the present study, we investigated the transcriptional activation function of the ISDR itself and the effect of amino acid mutations in the ISDR on this activity. The full-length or truncated NS5A cDNA with different ISDR sequences was cloned into a yeast or mammalian expression vector to form a fusion protein consisting of the GAL4 DNA-binding domain (GAL4-DBD) and NS5A protein. Following transfection, the transcriptional activities of these constructs were determined using beta-galactosidase (yeast) or chloramphenicol acetyltransferase (CAT) (mammalian cell) reporter gene expression under the control of GAL4 binding sites. In yeast, both the full-length sequence of NS5A-R (a clone with one aa mutation in the ISDR) and NS5A-S (a derivative of NS5A-R with six aa mutations in the ISDR) had no distinguishable transcriptional activity, whereas an amino-terminal deletion construct of NS5A-R (aa position 228-447) lacking 227 aa, showed remarkable activity with the relative value of 117.0 over that of the backbone vector. The same deletion mutant of NS5A-S produced five times higher activity with the relative value of 575.0, indicating that aa mutations in the ISDR profoundly affect this transcriptional activity. In a hepatoma cell line, HuH-7, the transcriptional activity was more prominent with a construct consisting of only the ISDR and short flanking sequences (aa 228-284) than larger deletion constructs of NS5A-R. Analysis using six different ISDR clones revealed that different mutations enhanced this activity to various extent compared with the wild-type ISDR. In particular, site-directed mutagenesis targeted to the aa position 252 showed that this aa residue had profound influence on the activity. These results suggest that the ISDR has a transcriptional activity, and it is enhanced by aa mutations that are also related to decreased viral load and increased interferon sensitivity. The possible association between transcriptional activation and interferon sensitivity or viral replication should be studied further.

De novo hepatitis C in children after liver transplantation

BACKGROUND

We describe the incidence, results of interferon therapy, and outcome of hepatitis C virus (HCV) hepatitis occurring de novo after pediatric orthotopic liver transplantation (OLT).

METHODS AND RESULTS

Of children undergoing OLT between 1984 and September 1996, 321 children survived for more than 1 year. Of these, 13 (4.0%) developed previously undiagnosed HCV disease, as suggested by HCV antibody testing and HCV polymerase chain reaction and confirmed by liver biopsy. Of the 117 children who received transplants before HCV screening of blood products or donors, 10.2% developed de novo HCV disease. The mean age at diagnosis of HCV hepatitis was 13.2+/-5.0 years, and the mean time to diagnosis after OLT was 8.1 years (range, 4-11 years). The mean alanine aminotransferase (ALT) level at diagnosis was 108 IU/ml, and the liver biopsy specimen showed chronic active or chronic persistent hepatitis in 11 children, cirrhosis in 1 child, and nonspecific changes in 1 child. Twelve children were treated with interferon-2alpha; children who weighed > or =20 kg received 3 x 10(6) units every other day, and those who weighed <20 kg received 1.5 x 10(6) units every other day. Four patients developed rapidly progressive liver failure while receiving interferon therapy and required urgent re-transplantation. Three of the four children again developed histologic evidence of recurrent HCV 4-6 months after the second OLT, and all three subsequently died of HCV-induced liver failure. One patient remains alive and well with no evidence of HCV recurrence and a negative HCV RNA. Of the remaining eight children treated with interferon, only two have had a sustained response (normal ALT) and one is now HCV RNA negative. HCV RNA levels did not correlate with outcome or disease severity. HCV antibody levels were unreliable, with two patients having negative HCV antibody but a positive HCV RNA at diagnosis. Six patients were able to be genotyped: four were la and two were 1b.

CONCLUSION

Overall mortality for de novo HCV hepatitis was 23%. Seventy-five percent of children who received a second transplant for HCV hepatitis had early histologic recurrence that led to liver failure and death. Interferon therapy resulted in a sustained improvement in ALT in only 15% of children. The time to onset and progression of clinical disease both in the original graft and the retransplant graft were accelerated compared with nonimmunosuppressed individuals.

High prevalence of hepatitis C virus genotype 6 among certain risk groups in Hong Kong

The genotype of hepatitis C virus (HCV) of 172 HCV-RNA positive serum specimens taken from patients with chronic liver diseases, thalassaemia major, chronic renal failure (CRF), haemophilia and intravenous drug abusers (IVDA) was determined by analysis of the amplified 5'UTR region by genotype-specific oligonucleotide probes and restriction fragment length polymorphism (RFLP). Six different genotypes and subtypes (1a, lb, 2, 3, 4 and 6) were found. Genotype lb was the predominant genotype among patients with chronic liver diseases (69.6%), followed by genotype 6 (18.8%), which was similar to that reported for blood donors in earlier studies. Pronounced differences in the distribution of genotypes were seen between the four risk groups. Patients with CRF had a similar distribution to those with chronic liver diseases, whilst the greatest diversity of genotypes was seen in patients with haemophilia, which was expected since they were given factor VIII manufactured overseas. Genotype 6 was particularly prominent in patients with thalassaemia major (50%) and IVDA (62.5%). It is possible that clonal spread of HCV genotype 6 has taken place among a closed subset of the population in Hong Kong through intravenous drug abuse.

Review article: interferon and hepatitis C--factors predicting therapeutic outcome

Hepatitis C chronically infects approximately 1.5% of Americans and is the most common clinical problem facing hepatologists. Since the virus was initially described in 1989, development of an effective therapy has been challenging. Although several different therapeutic agents have been used, no therapy has been shown to reliably eradicate the virus. Interferon-alpha, a cytokine with immunostimulatory and anti-viral properties, has become the therapy of choice for patients with chronic hepatitis C infection. Trials assessing the efficacy of interferon-alpha have characterized host and viral factors predictive of responses to treatment. A thorough understanding of these predictive factors is requisite to providing cost-effective therapeutic decisions for the patient with chronic hepatitis C infection.

Risk factors for hepatocellular carcinoma and its incidence after interferon treatment in patients with chronic hepatitis C. Osaka Liver Disease Study Group

To elucidate the risk factors for liver carcinogenesis and to examine the incidence of hepatocellular carcinoma (HCC) after interferon therapy, 1,022 chronic hepatitis C patients treated with interferon were followed by ultrasonography for 13 to 97 months (median 36 months). Sustained response with prolonged alanine aminotransferase normalization was found in 313 patients, transient response with alanine aminotransferase relapse after therapy in 304, and no response in 405. Forty-six developed HCC, of whom 5 were sustained responders, 9 were transient responders, and 32 were nonresponders. The cumulative incidence of HCC in transient responders was almost equal to that in sustained responders, and it was significantly higher in nonresponders than in sustained and transient responders (P=.0009). The seventh-year cumulative incidence rates of HCC in sustained responders, transient responders, and nonresponders were estimated to be 4.3%, 4.7%, and 26.1%, respectively. However, there was no significant difference in the cumulative incidence of HCC between patients with HCV subtype 1 and 2 (P=.14). Cox regression analysis showed that the risk of HCC development was not elevated in transient responders compared with sustained responders, but that the risk was 7.90-fold higher in nonresponders than in sustained responders (P=.008). Patients > or =55 years of age had a significantly higher risk ratio (4.65) than did those under 55 years of age (P=.006). The risk of HCC development in men was 4.35 times higher than the risk in women (P=.02). However, the degree of fibrosis was not a significant risk factor for the development of HCC (risk ratio, 3.16; P=.052). These results suggest that patients in the high-risk group of HCC after interferon therapy were those who showed no response, those who were older, and those who were male, and that such patients should be carefully followed using ultrasonography.

Combination therapy with thymosin alpha1 and interferon for the treatment of chronic hepatitis C infection: a randomized, placebo-controlled double-blind trial

Hepatitis C is a major cause of liver disease leading to cirrhosis. Although interferon (IFN) is the only approved therapy, treatment is characterized by low response rates and dose-limiting side effects. We evaluated the addition of thymosin alpha1 (TA1), an immunomodulatory peptide, to the standard treatment regimen for hepatitis C to determine if combination therapy shows biological activity using outcome measures including normalization of alanine aminotransferase levels, histological activity, and viral load during treatment. We performed a randomized, double-blind, placebo-controlled trial to compare the biological activity of a combination TA1 and IFN with that seen for IFN alone in patients with chronic hepatitis C infection. One hundred nine patients were randomized for intention to treat and received 1.6 mg of TA1 subcutaneously twice weekly and 3 MU of IFN three times weekly; 3 MU of IFN three times weekly and placebo TA1; or placebo for both agents. All patients had chronic HCV infection with confirmation of chronic hepatitis on liver biopsy. Biochemical responders were followed up until alanine aminotransferase (ALT) levels became abnormal or for 26 weeks, and relapsers were retreated for 26 weeks in the same treatment arm. One hundred three patients completed treatment for 26 weeks, and six patients dropped out. The groups were similar with regard to sex, gender distribution, baseline histological activity index (HAI) score, risk factors, and viral titers. End-of-treatment biochemical response was seen in 37.1% of patients treated with combination therapy, 16.2% of patients treated with IFN alone, and 2.7% of untreated controls by intent-to-treat analysis (IFN/TA1 vs. IFN, chi2 = 4.05, P = .04). HCV RNA clearance was seen in 37.1% of IFN/TA1-treated patients and 18.9% of IFN-treated subjects. Mean HCV RNA titers were significantly lower than baseline at weeks 8, 16, and 24 after drug initiation among patients treated with IFN/TA1 but not in the other treatment arms. Histological improvement, as evidenced by a decrease in HAI of more than two points, occurred in the combination therapy arm more frequently than in comparison groups. Cumulative sustained biochemical responses were 14.2% and 8.1% in the IFN/TA1 and IFN arms, respectively, based on an intention-to-treat model. The combination of TA1 and standard IFN treatment for chronic hepatitis C showed evidence of biological activity at the completion of treatment by biochemical, histological, and virological outcome measures. Further research involving longer duration and varied dosing is needed.

The biology of interferon-alpha and the clinical significance of anti-interferon antibodies

The therapeutic indications for Interferons (IFNs) have dramatically increased in number in recent years to include many different diseases of viral, malignant, angiogenic, allergic, inflammatory and fibrotic origin. In particular, the current pandemic of hepatitis C virus infection has further stimulated the requirement for a comprehensive understanding of both the mechanism of action of IFN and the reasons for therapeutic failure. The role of anti-IFN antibodies as a cause of treatment failure has been a particularly controversial area. In this review we will outline the biology and proposed mechanisms of action of IFN-alpha (IFN-alpha) and discuss the incidence, methods of detection and clinical significance of anti-IFN antibodies.

Hepatitis C

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

The influence of iron on chronic hepatitis C

It has recently been suggested that the hepatic iron concentration can be used to predict the response to interferon in patients with chronic hepatitis C. An hepatic iron concentration greater than 1100 microg/g appears to identify a group of patients that are unlikely to respond to alpha-interferon. It is not known whether this relationship can be explained by associated variables such as age, gender or disease severity or whether the hepatic iron concentration itself influences the response to interferon. Furthermore, the hepatic iron concentration is of no value in discriminating responders from non-responders in patients with hepatic iron concentrations less than 1100 microg/g. The possibility of improving response rates to interferon by pretreatment venesection needs to be explored but currently only limited data are available. Venesection results in a significant fall in the serum transaminases but the preliminary results regarding the efficacy of subsequent interferon therapy are unclear. Until the results of prospective controlled trials are available it is concluded that the available evidence does not support venesection before interferon therapy for chronic hepatitis C.

Influence of HLA haplotypes on the clinical courses of individuals infected with hepatitis C virus

The human leukocyte antigen is a crucial genetic factor that initiates or regulates immune response by presenting foreign or self antigens to T lymphocytes. The aim of this study was to investigate whether HLA polymorphism is associated with the onset or progression of liver injury in chronic hepatitis C virus (HCV) infection. We determined HLA class I antigens and class II alleles in 130 hepatitis C virus (HCV)-infected patients (33 carriers with persistently normal alanine transaminase [ALT] values and 97 patients with chronic liver disease [CLD]). HLA class I (A, B) was typed serologically, and class II (DRB1, DQB1) was typed by means of polymerase chain reaction-restriction fragment length polymorphism methods. The frequencies of DRB1*0405 and DQB1*0401 were higher in HCV-infected patients than in uninfected subjects. Among HCV-infected patients, the frequencies of B54, DRB1*0405, and DQB1*0401 were significantly higher in patients with CLD than in those carriers with persistently normal ALT values, whereas DRB1*1302, DRB1*1101, and DQB1*0604 were more frequently found in carriers with persistently normal ALT values than in patients with CLD. From extended haplotype analyses, in carriers with B54-DRB1*0405-DQB1*0401 haplotype, the risk of having liver injury was 13.2 times greater than in carriers with DRB1*0405-DQB1*0401 but without B54 [P = 0.0015, Haldane odds ratio = 13.2 (95% confidence interval, 1.7-103.8)]. In contrast, carriers with B44-DRB1*1302-DQB1*0604 had a 12.7-fold lower relative risk of developing liver injury compared to those with the haplotype containing B44 but not DRB1*1302-DQB1*0604 [P = 0.0076, Haldane odds ratio = 0.079 (0.009-0.695)]. Our findings show that extended haplotypes including class I B54 are closely associated with the progression of liver injury, whereas extended haplotypes including class II DRB1*1302-DQB1*0604 are associated with low hepatitis activity in chronic HCV infection.

Genotyping of hepatitis C virus isolates from Saudi patients by analysis of sequences from PCR-amplified core region of the virus genome

We investigated the genotype distribution of hepatitis C virus (HCV) among Saudi patients with chronic hepatitis C. Serum specimens from 119 native Saudi Arabian patients with chronic hepatitis C, as documented by serology and polymerase chain reaction (PCR) for HCV RNA, were used. Genotyping was performed by reverse transcription-PCR, using specific primers at the core region of HCV genome, and DNA sequencing of the resultant amplicons. It was found that the majority of samples (47.9%) belong to genotype 4, followed by subtype 1b (16.8%), and subtype 1a (10.1%). Twenty samples (16.8%) were not able to be typed by our method. We confirmed the results by cloning at least one PCR amplicon from each genotype, and determining the nucleotide sequence of the clones. Our findings suggest that genotype 4 is the most common among native Saudi Arabian patients with chronic hepatitis C infection. Genotypes 1b and 1a were also prevalent.

Mutations in the NS5A gene of hepatitis C virus in North American patients infected with HCV genotype 1a or 1b

Previous studies from Japan have described an association between a conserved sequence within the hepatitis C virus (HCV) genome and resistance to interferon (IFN) therapy for patients infected with HCV genotype 1b [Enomoto et al. (1995): Journal of Clinical Investigation 96: 224-230; Enomoto et al. (1996): New England Journal of Medicine 334:77-81]. The present study examines amino acid sequences surrounding the putative Interferon Sensitivity Determining Region (ISDR) of the NS5A gene of HCV in 21 North American patients with genotype 1a or 1b infection receiving recombinant IFN therapy. The ISDR consensus or intermediate pattern was observed in 13 of 14 NS5A clones from North American patients infected with genotype 1b. However, we found no evidence of the consensus ISDR sequence in any NS5A clones isolated from 15 patients with genotype 1a infection. In select cases, gel shift analysis showed no significant changes in the clonal frequency of the putative ISDR domain of HCV genotype 1a or 1b infected patients who were either nonresponsive to IFN therapy, or relapsed following withdrawal of IFN therapy. These results suggest that a conserved ISDR domain is neither associated with, nor responsible for, IFN resistance in North American patients infected with HCV genotype 1a, and demonstrate a need for further investigation into the reported association between ISDR consensus sequences and IFN resistance in genotype 1b clones.

Hepatitis C virus genotypes in liver transplant recipients: impact on posttransplant recurrence, infections, response to interferon-alpha therapy and outcome

BACKGROUND

End-stage liver disease due to hepatitis C virus (HCV) is the most common indication for liver transplantation in U.S. veterans. We investigated the influence of HCV genotypes on the incidence and timing of recurrent HCV hepatitis, survival, infectious morbidity, and response to interferon-alpha therapy in this unique patient population.

METHODS

HCV genotype was determined by direct sequencing of the NS5 region of HCV with type-specific primers.

RESULTS

Genotype 1a (66%, 32/47) was the predominant genotype. Type 1b was found in 25% (12/47) of patients and type 2b was found in 9% (4/47). Histopathologically recurrent HCV hepatitis developed in 53% (25/47) of the patients after transplantation. This group included 45% (14/31) of the patients with type 1a, 67% (8/12) of the patients with type 1b, and 25% (1/4) of the patients with type 2b (P>0.5). The time to recurrence and the severity of HCV recurrence as defined by aminotransferase levels or Knodell scores were not different among the three genotypes. There was a trend toward a higher incidence of major infections in patients with type 1b (75%) versus type 1a (48%) and type 2b (50%) (P=0.11). The response to interferon-a therapy did not differ significantly among the genotypes. Mortality at 5 years was 16% (5/31) in patients with genotype 1a, 42% (5/12) in patients with genotype 1b, and 50% (2/4) in patients with genotype 2b (P=0.06).

CONCLUSIONS

The incidence, time to recurrence, and response to interferon-alpha therapy did not differ between the various genotypes in our liver transplant recipients. However, there was a trend toward higher infectious morbidity and overall mortality in patients with genotype 1b after transplantation.