Interferon therapy in chronic hepatitis C virus: evidence of different outcome with respect to different viral strains

Amino-oxetanes as amide isosteres by an alternative defluorosulfonylative coupling of sulfonyl fluorides

Bioisosteres provide valuable design elements that medicinal chemists can use to adjust the structural and pharmacokinetic characteristics of bioactive compounds towards viable drug candidates. Aryl oxetane amines offer exciting potential as bioisosteres for benzamides-extremely common pharmacophores-but are rarely examined due to the lack of available synthetic methods. Here we describe a class of reactions for sulfonyl fluorides to form amino-oxetanes by an alternative pathway to the established SuFEx (sulfonyl-fluoride exchange) click reactivity. A defluorosulfonylation forms planar oxetane carbocations simply on warming. This disconnection, comparable to a typical amidation, will allow the application of vast existing amine libraries. The reaction is tolerant to a wide range of polar functionalities and is suitable for array formats. Ten oxetane analogues of bioactive benzamides and marketed drugs are prepared. Kinetic and computational studies support the formation of an oxetane carbocation as the rate-determining step, followed by a chemoselective nucleophile coupling step.

Genotype-related variations in proinflammatory and regulatory cytokine levels in treated and treatment-naive HCV-infected patients

Hepatitis C virus (HCV) modulates immune-related inflammatory responses to induce milder reactions leading to virus persistence. In this regard, the present study aimed to investigate the link between the HCV genotypes and the proinflammatory and regulatory cytokine levels. Ninety patients with hepatitis C infection (68 treatment-naive and 22 treated patients) and 76 healthy blood donors were studied. The serum levels of IFN-γ, IL-10, IL-17A, and IL-21 were measured by ELISA in the patients and healthy controls. IL-10, IL-17A, and IL-21 levels were significantly higher in HCV patients than in the healthy controls. The same cytokines were also higher in genotype 3a-infected patients compared with genotype 1a-infected patients. Interestingly, in treated patients, lower serum levels of IL-17A and IL-21 were detected in G3a-infected individuals, but not in those infected with G1a. G3a viral load displayed a significant correlation with IL-21 and IL-17A levels. In addition, G1a viral load correlated with IL-10 levels. In G3a-infected patients, a significant association was found between IL-17A serum levels and ALT. We found differences in IL-21 and IL-17A serum levels among HCV-infected patients which were genotype dependent. Since Th17-associated cytokines are associated with the progression of liver disease in HCV patients, IL-17A and IL-21 can be used as important biological markers for evaluating the immunopathogenesis of chronic hepatitis. Our results suggest that HCV G3a along with immune responses such as cytokines in HCV patients should be taken into account when interpreting clinical data and IFN-based therapeutic response.

Hepatitis C Virus Genotype and Subtype Distribution in Patient Specimens Tested at the University of Texas Medical Branch, Galveston, Between January 2011 and November 2014

Hepatitis C virus (HCV) genotype/subtype data are routinely generated in clinical laboratories to guide treatment. Genotype data can also inform genotype distribution and molecular epidemiology of HCV infections in patient populations and geographical regions that clinics/laboratories serve. The aim of this study was to determine the distribution of HCV genotypes/subtypes and their association with demographic characteristics among the patients that were routinely tested in the Molecular Diagnostics Laboratory at The University of Texas Medical Branch (UTMB) at Galveston. Among the 6573 patients tested between January 2011 and November 2014, the most frequent HCV genotype/subtype was 1a (65.3%), followed by 3a (11.5%), 1b (10.4%), and 2b (8.8%). Combined, genotype 4 and genotype 6 were found in less than 1% of this cohort. Approximately 1.3% of the patients presented multiple genotypes/subtypes. Factors independently associated with genotypes and subtypes were race/ethnicity, sex, and patient age.

Impact of HCV genetic differences on pathobiology of disease

Multiple HCV genotypes have been isolated worldwide. Genotype seems to be involved in the main pathological aspects of HCV infection. Insulin resistance, steatosis and progression toward cirrhosis, fibrosis and hepatocellular carcinoma establish and develop following genotype-specific mechanisms. Moreover genotype influences pharmacological treatment in term of dose and duration. Pathways involved in cell proliferation, apoptosis, lipid metabolism, insulin and interferon signaling are impaired to a different extent among genotypes, leading to distinct pathological settings. Genotype 1 is associated with a more aggressive disease with increased insulin resistance, worst response to therapy, higher risk of cirrhosis and hepatocellular carcinoma development, while genotype 3 is associated with increased steatosis and fibrosis. The identification and characterization of HCV types and subtypes provides insight into the different outcome of HCV infection and responsiveness to therapy. In the present article, we focused on the pathogenicity of HCV genotypes and their effect on disease progression and treatment.

Hepatitis C virus infection in dialysis patients

Hepatitis C virus (HCV) infection is a global health problem, common worldwide, leading to acute and chronic hepatitis and its consequences of hepatocirrhosis and hepatocellular carcinoma. Patients on hemodialysis belong to the high-risk group of HCV infection. The prevalence of HCV infection in dialysis patients ranges from 4% to more than 70% in some countries. The main reasons for such a high incidence of infections are a high prevalence of HCV infection in the general population, lack of standard infection precautions and effective vaccination, inadequate disinfection procedures of dialysis machines and other medical equipment, as well as spread of infection from patient to patient, especially in dialytic centers with a high percentage of infected patients. The diagnostic procedures useful in the evaluation of HCV infection are detection of anti-HCV antibodies, identification of HCV RNA, counts of virus copies, and identification of its genome. From the 6 major genotypes and multiple subtypes of the HCV, genotypes 1a and 1b are the most common in Europe and Japan, and 1b is responsible for more severe liver disease and aggressive course leading to liver fibrosis. Antiviral therapy of HCV+ dialysis patients with interferon-alpha (INF-alpha) gives slightly better results than in the general population, but is poorly tolerated and associated with side effects. Although ribavirin in not recommended for dialysis patients, the addition of small doses of this compound to pegylated INF is discussed, especially for patients in whom previous infection treatment failed.

Chronic Hepatitis C and Genotyping: The Clinical Significance of Determining HCV Genotypes

Chronic hepatitis C, attributed to infection with hepatitis C virus (HCV), is a global health problem. The overall prevalence of viral hepatitis worldwide is estimated to be 3–5% with over 175 million people infected with HCV. Clinically, HCV can establish a persistent, chronic infection contributing to progressive liver disease, including cirrhosis and hepatocellular carcinoma (HCC), requiring intensive treatment regimens, possible liver transplantation and long-term care. Due to the chronic nature of HCV infection and the tremendous burden on healthcare resources, clinicians and laboratorians have looked for key epidemiological, pathological and viral characteristics that may provide insight into disease progression, severity and response to therapy to permit the administration of effective therapeutic regimens as well as long-term management of infected individuals. Determination of viral genotype has been identified as one parameter that could provide direction in the clinical management of patients with chronic HCV infections. The following review provides background on determination of HCV genotypes and the relevance of viral genome characterization in the current clinical setting.

Determination of HCV genotype by direct sequence analysis of quantitative PCR products

Hepatitis C virus (HCV) genotyping, combined with quantitative evaluation of HCV RNA, may be beneficial for the management of chronic hepatitis C and in the selection of candidates for interferon treatment. In this study, the COBAS AMPLICOR HCV MONITOR test, a commercially available quantitative assay for HCV RNA, was used. Amplification products obtained from HCV-positive cases were subjected to direct sequencing and genotyping based on seven phylogenetically informative regions within the 5'UTR. Results were compared with those obtained by INNO-LiPA assay. Typing results yielded by both methods were in complete accordance for type and subtype assignment. Twenty-nine of 500 specimens (5.8%) were unclassifiable and belonged to samples with a titer of <70.000 IU, as determined by quantitative assay. Despite this limitation, the overall gain in efficiency, the low rate of test failure and a better resolution of mixed genotypes all constitute a considerable advantage of this system over the commercial hybridization technique for routine clinical laboratory use.

Hepatitis C virus genotyping: interrogation of the 5' untranslated region cannot accurately distinguish genotypes 1a and 1b

Although the 5' untranslated region (5' UTR) is the most conserved region of the hepatitis C virus (HCV) genome, it has been suggested that interrogation of this region is sufficient for determination of the HCV genotype. We compared two methods of determination of the HCV genotype: (i) direct sequencing of the DNA of the NS-5b region and (ii) reverse line probe assay (LiPA; INNO-LiPA HCV II; Innogenetics N.V.) of the 5' UTR. There was 100% concordance between the two methods for genotype but only 80% concordance for subtype. A significant percentage of genotype 1a isolates were misclassified by LiPA as genotype 1b. Sequence analysis revealed that the only consistent difference in the 5' UTR for these genotype 1a isolates misclassified as genotype 1b was a single nucleotide (A/G) at position -99 of the HCV genome. All isolates with discordant results analyzed had a G at this position, consistent with LiPA determination of these samples as subtype 1b. However, sequence analysis of 222 nucleotides in the NS-5b region clearly identified all of these isolates as subtype 1a. Population distribution data from the University of Pittsburgh Medical Center of over 200 samples analyzed by sequencing of the NS-5b region and over 1,000 samples analyzed by LiPA also indicated that INNO-LiPA HCV II cannot accurately differentiate HCV genotype 1a isolates from HCV genotype 1b isolates. We provide evidence that the A/G at position -99 represents a sequence polymorphism in the HCV genome that cannot differentiate subtype 1a from subtype 1b isolates. In conclusion, the 5' UTR is not heterogeneous enough for use in determination of the HCV subtype and cannot be used for differentiation of HCV genotypes 1a and 1b.

Human leucocyte interferon-alpha in the treatment of chronic hepatitis C

AIM

To assess the efficacy of different schedules of human leucocyte interferon alpha in chronic hepatitis C.

PATIENTS AND METHODS

A total of 213 naive patients with chronic hepatitis C were treated with 4 different schedules of human leucocyte interferon alpha. Sustained response was defined as persistently normal alanine amino transferase values with negative serum hepatitis C virus-RNA up to 12 months after therapy withdrawal.

RESULTS

Rates of sustained response were 16% with 3 MU tiw for 6 months, 33% with 6 MU tiw for 5 months after a priming dose of 9 MU tiw for a month, 32% with 3 MU tiw for 12 months and 20% with 3 MU daily for 6 months. The major factors affecting the response rate were age and the hepatitis C virus genotype, as a sustained response was significantly higher in patients under 45 years and infected by hepatitis C virus types other than hepatitis C virus-1. Treatment was well tolerated and side-effects and drop-out events were similar to those described with other types of alpha-interferons.

CONCLUSIONS

Human leucocyte interferon alpha appears to be equivalent to recombinant interferon-alpha in the treatment of chronic hepatitis C.

Nested restriction site-specific PCR to detect and type hepatitis C virus (HCV): a rapid method to distinguish HCV subtype 1b from other genotypes

Genotypic differentiation of hepatitis C virus (HCV) has become an integral part of clinical management and epidemiologic studies of hepatitis C infections. Thus, it is extremely important in areas such as the Czech Republic, where current instrumentation and kits for assessing HCV infection are too costly for widespread use. We describe a new and relatively inexpensive method called nested restriction site-specific PCR (RSS-PCR) that generates a "fingerprint" pattern to represent an HCV genotype without the use of restriction endonucleases and that specifically differentiates HCV genotype 1b from the other HCV genotypes. The RSS-PCR method was applied directly to serum samples from patients with hepatitis C from the Czech Republic and from patients with known HCV genotypes from the United States. The method was validated by comparison of the subtype determined by RSS-PCR to the subtype determined from analysis of the 5' noncoding region (NC) or the nonstructural protein gene (NS5b) nucleotide sequence of HCV in these clinical samples. From 75 Czech samples containing HCV RNA, three distinct RSS-PCR patterns were observed; 54 were predicted to contain subtype 1b, 19 were predicted to contain subtype 1a, and 2 were predicted to contain subtype 3a. Among 54 samples predicted to contain HCV genotype 1b, all were confirmed by their 5' NC or NS5b sequences to be subtype 1b. Thus, both the sensitivity and specificity of the RSS-PCR test for the differentiation of HCV subtype 1b from the others were 100%. While the assay described here was designed to specifically differentiate HCV subtype 1b from the other HCV genotypes, the RSS-PCR method can be modified to differentiate any HCV genotype or subtype of interest. Its simplicity and speed may provide new opportunities to study the epidemiology of HCV infections and the relationship between HCV genotypes and clinical outcome by more laboratories throughout the world.

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

Methodological issues in papers on IFN therapy: time for reappraisal

We conducted an analytical review of 194 full papers on interferon (IFN) therapy for chronic hepatitis C to evaluate current methodology (i.e. study design, criteria for evaluating the efficacy of therapy and predictors of response). Of the papers evaluated, 64 were randomized controlled trials (RCT), 40 were non-randomized controlled trials (NRCT) and 90 were observational studies (OS). The methodological analysis was focused mainly on clinical trials. The number of patients enrolled in RCT was higher compared with the number enrolled in NRCT. Uniform enrolment criteria were used in less than 50% of the trials. Only 20% of RCT and 2.5% of NRCT used criteria for defining sample size. The response rate was calculated on an intention-to-treat basis in 36 of the RCT and in 14 of the NRCT. The outcome of treatment and the criteria employed to define the response to treatment were found to be far from standardized. In 51.5% of the RCT and 42.5% of the NRCT, normalization of alanine aminotransferase (ALT) level at the end of follow-up was the only marker of response studied. Only 57.6% of the trials considered histological evidence as an important outcome. Among the clinical trials, 71.1% evaluated predictors of good response to IFN therapy. In 51% of the OS, ALT normalization by the end of follow-up was the only criterion for defining response. In conclusion, to ensure a high level of reliability in comparing or combining the results of different studies, some basic general requirements must be followed when planning trials on antiviral therapy.

Clinical significance of hepatitis C virus genotypes

On the basis of phylogenetic analysis of nucleotide sequences, multiple genotypes and subtypes of hepatitis C virus (HCV) have been identified. Characterization of these genetic groups is likely to facilitate and contribute to the development of an effective vaccine against infection with HCV. Differences among HCV genotypes in geographic distributions have provided investigators with an epidemiologic marker that can be used to trace the source of HCV infection in a given population. HCV genotype 1 may represent a more aggressive strain and one that is less likely to respond to interferon treatment than HCV genotype 2 or 3. However, these observations require confirmation before HCV genotyping can be used in clinical settings.

[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.

Clinical use of hepatitis C virus tests for diagnosis and monitoring during therapy

This article reviewed various methods used for the diagnosis and monitoring of HCV infection and discusses potential clinical applications. Substantial improvements have recently been made in assay technology. Moreover, the role of molecular testing in the clinical setting of hepatitis C is becoming better defined. The major challenge facing clinical laboratories is the further refinement, implementation, and standardization of optimized molecular tests, so that reliable data may be made available to clinicians. In turn, clinicians must understand the limitations of each methodology, including the variability of testing that may occur among different laboratories. As more experience is gathered, molecular testing will probably provide important data regarding the most effective use of current and future therapies for individual patients to achieve maximum benefit in the management of hepatitis C.

Impact of alcohol on the histological and clinical progression of hepatitis C infection

In patients infected with the hepatitis C virus (HCV), 20% to 30% will progress to cirrhosis in over two to three decades. Viral and host factors that are important in the clinical and histologic progression of HCV infection are not entirely certain. It has been suggested that liver disease is worse in alcoholics infected with HCV. In the present retrospective study, we examined the effect of moderate alcohol intake on the histologic and clinical progression of HCV infection and assessed whether other variables such as gender, length of exposure, mode of exposure, HCV RNA levels, and ferritin levels also independently impacted disease progression. Liver biopsies were analyzed for the degree of fibrosis, presence of cirrhosis, and histologic activity by using the Histologic Activity Index of Knodell. Patients were divided into two groups based on whether their alcohol intake was significant or not significant. Significant alcohol intake was defined as > 40 g alcohol/day in women and > 60 g of alcohol/day in men for > 5 years. Groups were further divided based on the decades of exposure to HCV. There was no difference in the age or length of exposure to HCV in the alcohol and the alcohol-free group. HCV RNA serum levels, ferritin levels, and viral genotypes were similar in both groups. There was a two- to threefold greater risk of liver cirrhosis and decompensated liver disease in the alcohol group. Also, the rate to which subjects developed cirrhosis was faster in the alcohol group with 58% being cirrhotic by the second decade as opposed to 10% being cirrhotic in the nonalcohol group by the second decade. The histologic and clinical acceleration of liver disease was independent of the mode of exposure or sex. In summary, alcohol intake is an independent risk factor in the clinical and histologic progression of HCV infection.

Rapid genotyping of hepatitis C virus by direct cycle sequencing of PCR-amplified cDNAs and capillary electrophoresis analysis

There is an increasing demand for the genotyping of hepatitis C virus (HCV), since it has been shown that different HCV genotypes are associated with distinct profiles of pathogenicity and responses to antiviral treatment. Hence, there is a need for a simple and precise genotyping assay for routine diagnosis of HCV types and subtypes. Here we show that direct sequencing, considered as the reference method, can provide an accurate and rapid method for large-scale screening of HCV genotypes. PCR-amplified cDNAs of the HCV 5' non-coding region (5' NCR) were obtained from the widespread "Amplicor" HCV detection system. Semi-purified PCR products were directly cycle-sequenced in a single tube using multicolour dye terminator chemistry. Sample loading, electrophoresis and sequence analysis were automatically achieved by a capillary electrophoresis-based genetic analyser. Out of a total of 500 samples, HCV subtype 1b accounted for the majority of the infections (41%), followed by HCV 3 (31%) and HCV 1a (22%). This procedure failed to identify a genotype in only 3 samples. In addition, several cases of mixed HCV infection were also documented. The combination of direct cycle sequencing of PCR products with capillary electrophoresis provides a simple and rapid method convenient for routine HCV genotyping analysis.

HCV genotypes in patients with chronic hepatitis C in Croatia

The determination of hepatitis C virus (HCV) genotype is an important epidemiological parameter in patients with chronic hepatitis C, while its clinical significance is still a matter of debate. The HCV genotypes in a group of 203 Croatian patients with chronic hepatitis C were examined. Genotypes were correlated to different risk factors, age, duration of the disease, liver histology activity and level of viremia. HCV-RNA was detected in each serum by means of reverse transcription PCR. Genotypes were determined from the amplificate by reverse hybridization in a line probe assay. The level of viremia was assessed by branched DNA (bDNA) signal amplification. The most common genotype was 1b (61.1% of patients), followed by 3a (26.1%), and 1a (10.8%). Other genotypes such as 2a and 4 were only rarely found in our patients (2%). Genotype 1b was most commonly acquired via blood transfusion, while genotype 3a was strongly related to intravenous drug use. Genotype 1b was associated with older age (mean 42.6 vs 29.3 years), longer duration of the disease (mean 6.0 vs 3.5 years), higher histologic activity score (mean 13.2 vs 10.6) and higher viremia (mean 9.06 vs 5.93 Meq/ml) at statistically significant levels (p < 0.001) when compared to genotype 3a. The prevalence of HCV genotypes follows the patterns of southeastern European countries, except for a lower prevalence of genotype 2. The observation that genotype 1b is associated with higher viremia and more severe liver injury is confirmed.

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.

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.

Hepatitis C virus: molecular biology and genetic variability

The pathogenetic mechanisms of hepatitis C virus (HCV) infection are poorly known. An understanding of HCV biology and the potential clinical impact of HCV genetic variability is essential to managing, treating, and preventing HCV infections. HCV is a member of the Flaviviridae viral family. Its genome is a positive, single-strand RNA molecule. The structure of the HCV particles is poorly known due to the lack of an efficient cell culture system as well as a striking heterogeneity in density. The core protein may have a regulatory role on both viral and cellular gene expression. The mechanisms of HCV-RNA replication may include synthesis of negative strand intermediates, which drive synthesis of new positive RNA genomes. New procedures have been developed to better identify and characterize the HCV-RNA genome. The mechanisms of HCV persistence are currently unknown, although it is known that HCV chronicity develops despite humoral and cellular responses to HCV proteins. HCV-RNA shows significant genetic variability with an estimated rate of nucleotide change of approximately 10(-3) substitutions/site/year. Currently, three major HCV genotypes and three to seven minor subtypes can be distinguished. The geographical distribution of these genotypes and subtypes varies significantly. It appears that poor clinical response to interferon (IFN) is more common with HCV genotype 1. In addition, some studies have shown an association between chronic infection, severe chronic hepatitis, and cirrhosis with subtype 1b. Further, there is evidence for a potential direct effect of HCV in liver carcinogenesis, with subtype 1b possibly being an independent risk factor for hepatic carcinoma development. HCV-RNA circulates as a population of RNA molecules, which creates a heterogeneity referred to as "quasispecies." It is possible that some HCV strains might have direct clinical implications. It may be that highly heterogeneous populations observed prior to treatment might correlate with a lower rate of response to IFN therapy.

Regression of monoclonal B-cell expansion in patients affected by mixed cryoglobulinemia responsive to alpha-interferon therapy

BACKGROUND

Several authors have reported on the effectiveness of alpha-interferon (IFN-alpha) in the treatment of patients with mixed cryoglobulinemia. This prompted the authors to investigate the long term effects of this drug on clinical, hematologic, and virologic parameters in a group of 20 patients (13 women and 7 men) affected by mixed cryoglobulinemia.

METHODS

In all patients, bone marrow biopsy, phenotyping of marrow cells, and polymerase chain reaction (PCR) immunoglobulin gene rearrangement in peripheral blood lymphocytes were performed before therapy and at the end of the follow-up. A liver biopsy was obtained in patients with biochemical signs of chronic liver disease. The presence of hepatitis C virus (HCV) RNA in serum was assessed by detection of anti-HCV antibodies, and by PCR amplification of the 5' untranslated region of HCV. The HCV genotype was also determined by PCR amplification of the core region of the virus with type-specific primers. The treatment schedule followed by all patients was 3 million units of recombinant IFN-alpha 2b 3 times weekly for 1 year.

RESULTS

In 6 patients, the marrow histology before therapy showed a massive (more than 50%) monomorphous infiltration by plasmacytoid lymphocytes, indicating the presence of low grade non-Hodgkin's lymphoma. Anti-HCV antibodies were present in 19 (95%) subjects, and HCV-RNA was detectable in all patients. In addition, all patients affected by Type II mixed cryoglobulinemia showed a monoclonal B-cell expansion in peripheral blood mononuclear cells (PBMC). With therapy, 5 patients (25%) achieved a complete response and 11 patients (55%) a partial response, whereas minor responses were observed in the remaining 4 patients (20%). One of the complete responders and all patients showing partial responses relapsed a few months after therapy withdrawal. At the end of the follow-up, four patients had obtained a complete remission. Bone marrow examination showed that B-lymphocytic monoclonal infiltrate disappeared in three patients. Moreover, these three patients had become negative for B-cell expansion in PBMC. Lack of response, or relapse, was associated with the presence of Type II HCV.

CONCLUSIONS

HCV may be the cause of mixed cryoglobulinemia. The disease is associated with a high prevalence of bone marrow B-cell lymphomas. IFN-alpha appears to be an effective agent for the treatment of mixed cryoglobulinemia. It also seems able to determine regression of the lymphoproliferative disorder. The HCV genotype appears to be the most important predictive factor for the response to antiviral therapy.

Accurate quantification of hepatitis C virus (HCV) RNA from all HCV genotypes by using branched-DNA technology

In studies monitoring disease progression and therapeutic response, it is essential that the method used for hepatitis C virus (HCV) quantification not be influenced by genotypic variability. The branched DNA assay provides a reliable method for the quantification of HCV RNA. A modified set of oligonucleotide probes for the branched DNA assay was developed to enhance the efficiency of binding to genotypic variants of HCV. The improved branched DNA assay (HCV RNA 2.0) yielded highly reproducible quantification of hepatitis C virus RNA and displayed a nearly 600-fold dynamic range in quantification up to 120 Meq of HCV RNA per ml. The quantification limit was set at 0.2 Meg of HCV RNA per ml to ensure a specificity of > or = 95%. With this lowered quantification limit and the enhanced hybridization of the probes, the HCV RNA 2.0 assay exhibited a high level of sensitivity (96%) and was virtually unaffected by the genotypic variability of HCV. The HCV RNA 2.0 assay may be a useful tool for following HCV RNA levels throughout the course of disease, selecting patients for therapy, and evaluating therapeutic response.

High-dose interferon-alpha 2b for re-treatment of nonresponders or relapsing patients with chronic hepatitis C. A controlled randomized trial

Relatively few patients with chronic hepatitis C treated with standard doses of interferon-alpha 2b (3 million units per week for 24 weeks) have a sustained response. Our aim was to evaluate whether higher doses of interferon would improve this rate of response. Twenty-four patients with chronic hepatitis C who had failed to respond to (N = 21) or had relapsed after (N = 3) an initial course of standard interferon therapy were randomized to 15 million units (N = 13) or 22.5-30 million units per week (N = 11) for 24 weeks. Five of 13 subjects given 15 million units per week and 3/11 of subjects given 22.5-30 million units per week had complete normalization of serum alanine aminotransferase levels during therapy. Five patients (24% who had not responded to standard interferon had a complete response to high-dose interferon during therapy. Only one patient had a sustained response, with normal serum alanine aminotransferase 24 weeks after stopping interferon. Six patients were withdrawn before completing treatment, five in the 22.5-30 million unit per week group. We conclude that higher doses of interferon ameliorate the severity of hepatitis in patients who failed to respond to or relapsed after standard interferon therapy, but are unlikely to produce a sustained response. High-dose therapy is associated with an increase in side effects.