Showing papers by "Fabien Zoulim published in 2007"

Meta-analyses of FibroTest diagnostic value in chronic liver disease

Abstract: Background FibroTest (FT) is a biomarker of liver fibrosis initially validated in patients with chronic hepatitis C (CHC). The aim was to test two hypotheses, one, that the FT diagnostic value was similar in the three other frequent fibrotic diseases: chronic hepatitis B (CHB), alcoholic liver disease (ALD) and non-alcoholic fatty liver disease (NAFLD); and the other, that the FT diagnostic value was similar for intermediate and extreme fibrosis stages.

The way forward in HCV treatment — finding the right path

Abstract: Infection with the hepatitis C virus (HCV) represents an important health-care problem worldwide. The prevalence of HCV-related disease is increasing, and no vaccine is yet available. Since the identification of HCV as the causative agent of non-A, non-B hepatitis, treatment has progressed rapidly, but morbidity and mortality rates are still predicted to rise. Novel, more efficacious and tolerable therapies are urgently needed, and a greater understanding of the viral life cycle has led to an increase in the number of possible targets for antiviral intervention. Here we review the specific challenges posed by HCV, and recent developments in the design of vaccines and novel antiviral agents.

Occult HBV infection may represent a major risk factor of non-response to antiviral therapy of chronic hepatitis C.

Abstract: Occult hepatitis B virus (HBV) infection is common in chronic hepatitis C patient. However, its significance and consequences are still unclear. The aim of this study was to evaluate the prevalence of occult HBV among HCV chronic carriers in France and to assess its impact on liver histology and response to antiviral therapy. To this end a cohort of 203 patients with chronic hepatitis C without hepatitis B surface antigen (HBsAg) has been examined. Serum HBV-DNA was detected using a highly sensitive PCR with primers located in the S and X genes. HBV viraemia levels were further determined by real-time PCR. Results showed that 47 of 203 (23%) patients had occult HBV infection with a low HBV load (10(2)-10(4) copies/ml) but significantly higher HCV-RNA titers (P 0.05). In conclusion, HBV-DNA is found in 1/4 of French chronic hepatitis C patients regardless of the presence of anti-HBc. Such an occult HBV co-infection is associated with more severe liver disease, higher HCV viral load and decreased response to antiviral therapy irrespective of HCV genotypes.

Impact of Highly Active Antiretroviral Therapy (HAART) on the Natural History of Hepatitis B Virus (HBV) and HIV Coinfection: Relationship between Prolonged Efficacy of HAART and HBV Surface and Early Antigen Seroconversion

Abstract: Background. Coinfection with hepatitis B virus (HBV) in human immunodeficiency virus (HIV)-infected patients is common. However, little is known about the natural history of chronic hepatitis B in HIV-infected populations, especially the impact of highly active antiretroviral therapy (HAART) on the outcome of HBV early antigen (HBeAg) and HBV surface antigen (HBsAg) status. Methods. The characteristics of 92 patients coinfected with HIV and HBV were retrospectively assessed before and after HAART and lamivudine treatment to determine the impact of treatment on chronic hepatitis B and factors associated with HBeAg and/or HBsAg seroconversion. Results. During follow-up, 82 patients received antiretroviral therapy, 79 of whom received HAART. Twenty-eight of the 76 patients who were administered lamivudine therapy developed lamivudine resistance mutations. While receiving antiretroviral therapy, 10 of 59 HBeAg-positive patients developed antibody to HBeAg, 3 of 10 cleared HBsAg, and 2 of 3 developed antibody to HBsAg. Two of 23 HBeAg-negative patients cleared HBsAg and developed antibody to HBsAg. HBeAg and/or HBsAg seroconversion combined with an undetectable HBV DNA level (i.e., an HBV response) correlated with a sustained HIV response (P = .001), shorter duration of antiretroviral therapy (P = .058), and more-severe disease, as evaluated by Centers for Disease Control and Prevention staging (for stage B vs. stage A, P = .029; for stage C vs. stage A, P = .069). For patients with elevated baseline alanine aminotransferase levels, the HBV response correlated significantly with a greater increase in CD4 cell count while receiving HAART. Conclusions. In HIV-HBV-coinfected patients, HBV response correlated with a sustained HIV response to antiretroviral therapy, usually HAART including lamivudine.

Etanercept treatment for three months is safe in patients with rheumatological manifestations associated with hepatitis C virus

Abstract: Objective. The treatment of the rheumatological manifestations associated with hepatitis C virus (HCV) remains difficult. To examine the safety of anti-tumour necerosis factor-� treatment, nine patients having rheumatological manifestations associated with HCV were treated with etanercept 25 mg twice a week for 3 months. Methods. Five patients had a positive viral load at study entry (Group I), four were negative (Group II). Clinical data recorded were: disease duration, painful and swollen joint count, patient global and physician global assessment, the number of 18 specified fibromyalgia tender points and the Health Assessment Questionnaire score. Laboratory studies included checking for the presence of cryoglobulinaemia and transaminase levels. Quantitative HCV viral RNA was performed by real-time polymerase chain reaction (PCR). Results. At 3 months, no patient was found to have evidence of increased hepatic inflammation based on serial serum transaminase levels. In the five patients from Group I with detectable HCV RNA, no significant viral load increase was observed. No reactivation was observed in the four patients from Group II with undetectable HCV RNA. The effect on the clinical rheumatological manifestations was more heterogeneous but appears to be lower than that observed in rheumatoid arthritis. Conclusion. In this phase II open short-term study, etanercept appeared to be safe in patients with articular manifestations associated with HCV.

Selection of hepatitis B virus (HBV) vaccine escape mutants in HBV-infected and HBV/HIV-coinfected patients failing antiretroviral drugs with anti-HBV activity.

Abstract: Background: Given the overlap between envelope and polymerase in the hepatitis B virus (HBV) genome, changes in antigenic sites of the HBV surface antigen may occur as a result of selection of drug-resistance mutations. Methods: Serum HBV-DNA was isolated from 71 patients with chronic hepatitis B receiving anti-HBV drugs for longer than 12 months, 52 of whom were HIV-positive. The reverse transcriptase/ envelope gene from each HBV isolate was amplified using a nested polymerase chain reaction (PCR) covering 720 bp (aa 48 to 288), which includes all known nucleos(t)ide analogue resistance mutations in HBV Results: All but 13 patients had received lamivudine. Of the rest, 10 HBV-monoinfected subjects had received adefovir and 3 HBV/HIV-coinfected patients had been treated with tenofovir. Only lamivudine-resistance-associated mutations produced changes in the HBV envelope antigenic sites. Lamivudine resistance mutations were more frequent in HBV genotype A than D (P = 0.014). Contrary to mono-infected individuals, HBV genotype A was the predominant genotype among HBV/HIV-coinfected patients. The triple-HBV mutant rtV173L + rtL180M + rtM204V, which has been shown to produce a diminished hepatitis B surface (HBs) antigen-antibody binding, was found in 3 individuals, all coinfected with HIV and HBV Conclusion: Circulation of HBV encoding envelope mutations with diminished HBs antigen-antibody binding as result of selection of drug-resistance mutations may occur, particularly in patients infected with HBV genotype A, the most prevalent genotype among HBV/ HIV-coinfected patients. Such mutations might represent a public health concern because of the potential risk of transmission of HBV drug- and vaccine-resistant strains.

Reduction of the infectivity of hepatitis C virus pseudoparticles by incorporation of misfolded glycoproteins induced by glucosidase inhibitors.

Abstract: Folding and assembly into complexes of some viral glycoproteins are exquisitely sensitive to endoplasmic reticulum (ER) alpha-glucosidase inhibition, which prevents the trimming of glucose from N-linked glycans. Derivatives of deoxynojirimycin (DNJ) iminosugars, which are potent alpha-glucosidase inhibitors, were shown to have antiviral activity against bovine viral diarrhea virus, a pestivirus related to hepatitis C virus (HCV). The aim of this study was to determine whether these inhibitors would affect HCV infectivity and to provide novel insights on their mechanism of action. The overall antiviral activity of glucosidase inhibitors was shown by using the two most relevant models currently available: the cell-culture model enabling complete replication of the HCV JFH1 strain in Huh7.5 cells, and infectious HCV pseudotyped particles (HCVpp) produced in HEK-293T cells that display functional E1-E2 glycoprotein complexes. By using the latter model, it is shown that the inhibition of alpha-glucosidases by iminosugars results in the misfolding and misassembly of HCV glycoprotein pre-budding complexes. This inhibition of the assembly of E1-E2 in the ER of transfected HEK-293T cells leads to a reduction in the incorporation of E1-E2 complexes into HCVpp. More importantly, it is demonstrated that the infectivity of HCVpp that are released under treatment is reduced and that this reduction in infectivity is due to the incorporation of misfolded envelope glycoproteins in secreted particles. These properties suggest the potential usefulness of DNJ derivatives in combating HCV infection.

Glucosidase inhibitors as antiviral agents for hepatitis B and C.

Abstract: HBV and HCV infections are a major public health concern. New antiviral drugs are urgently needed with improved efficacy. Compounds that specifically target viral enzymes are the most attractive in terms of drug development and are therefore the most studied. However, antiviral strategies based entirely on this class of compounds encounter problems caused by the emergence of viral escape mutants, as already widely described for HIV. One way to prevent or delay viral resistance is to combine antiviral agents that target different steps of the virus life cycle. Future therapy may also combine such virus-specific antivirals with compounds targeting host proteins or functions. In this respect, viral morphogenesis and infectivity represent interesting, and still unexploited, novel molecular targets. Endoplasmic reticulum glucosidase inhibitors have demonstrated anti-HBV and anti-HCV properties by inhibiting viral morphogenesis and infectivity. One such compound, celgosivir, is currently being evaluated in clinical trials against HCV infection, and encouraging phase IIa data have been disclosed. This review will discuss HBV and HCV morphogenesis, with a particular focus on the role of N-glycosylation for viral protein folding and assembly, and will present the antiviral properties of glucosidase inhibitors.

Antiviral-resistant hepatitis B virus: can we prevent this monster from growing?

Abstract: SUMMARY. Despite the recent progress in antiviral therapy of chronic hepatitis B, clinical experience has shown that antiviral drug resistance is inevitable with the administration of nucleoside analog monotherapy. The long-term persistence of the viral genome in infected cells and the high rate of spontaneous mutation is the basis for the selection of HBV mutants that are resistant to polymerase inhibitors. Selection of antiviral-resistant mutations leads to a rise in viral load and progression of liver disease. The incidence of antiviral resistance depends on the potency and genetic barrier to resistance of the antiviral drug, highlighting the importance of the choice if first line therapy. The determination of cross-resistance profile of each drug has allowed the design of rescue therapy for patients with virologic breakthrough. Early diagnosis and treatment intervention allow the majority of patients to maintain in clinical remission despite the occurrence of drug resistance. Clinical studies are ongoing to determine the best strategy to prevent or delay antiviral drug resistance and of its impact on liver disease.

Characterization of a New Sensitive PCR Assay for Quantification of Viral DNA Isolated from Patients with Hepatitis B Virus Infections

Abstract: Sensitive and accurate quantification of hepatitis B virus (HBV) DNA is necessary for monitoring patients with chronic hepatitis receiving antiviral therapy in order to determine treatment response and to adapt therapy in case of inadequate virologic control. The development of quantitative PCR assays has been crucial in meeting these needs. The objective of this study was to compare the performance of a new real-time PCR assay (Abbott RealTime) for HBV DNA with that of three other commercial assays for the detection of HBV DNA. These were the Versant 3.0 branched-chain DNA assay, the Cobas Amplicor HBV Monitor test, and the Cobas AmpliPrep-Cobas TaqMan hepatitis B virus assay (CAP-CTM). HBV DNA was measured in blood samples taken from two cohorts of patients with chronic hepatitis. HBV DNA levels measured with the Abbott RealTime assay were highly correlated with those measured with the other three tests over their respective dynamic ranges (r, 0.88 to 0.96). The sensitivity (detection limit, 10 IU/ml) and dynamic range of the Abbott RealTime assay (101 to 109 IU/ml) was superior to that of the Versant assay. The RealTime assay recognized both HBV strains belonging to genotypes A to G and those bearing polymerase gene mutations equivalently. In conclusion, this study demonstrates the utility of the Abbott RealTime assay for monitoring HBV DNA levels in patients with chronic hepatitis B. Its sensitivity and wide dynamic range should allow optimal monitoring of antiviral therapy and timely treatment adaptation.

In Vitro Activity of 2,4-Diamino-6-[2-(Phosphonomethoxy)Ethoxy]-Pyrimidine against Multidrug-Resistant Hepatitis B Virus Mutants

Abstract: The susceptibilities of drug-resistant hepatitis B virus (HBV) mutants to lamivudine, adefovir, tenofovir, entecavir, and 2,4-diamino-6-[2-(phosphonomethoxy)ethoxy]-pyrimidine (PMEO-DAPym), a novel acyclic pyrimidine analogue, were assessed in vitro. Most drug-resistant mutants, including multidrug-resistant strains, remained sensitive to tenofovir and PMEO-DAPym. Therefore, the latter molecule deserves further evaluation for the treatment of HBV infection.

Critical Role of the 36-Nucleotide Insertion in Hepatitis B Virus Genotype G in Core Protein Expression, Genome Replication, and Virion Secretion

Abstract: Frequent coinfection of hepatitis B virus genotype G with genotype A suggests that genotype G may require genotype A for replication or transmission. In this regard, genotype G is unique in having a 12-amino-acid extension in the core protein due to a 36-nucleotide insertion near the core gene translation initiation codon. The insertion alters base pairing in the lower stem of the pregenome encapsidation signal, which harbors the core gene initiator, and thus has the potential to affect both core protein translation and pregenomic RNA encapsidation. Genotype G is also unusual for possessing two nonsense mutations in the precore region, which together with the core gene encode a secreted nonstructural protein called hepatitis B e antigen (HBeAg). We found that genotype G clones were indeed incapable of HBeAg expression but were competent in RNA transcription, genome replication, and virion secretion. Interestingly, the 36-nucleotide insertion markedly increased the level of core protein, which was achieved at the level of protein translation but did not involve alteration in the mRNA level. Consequently, the variant core protein was readily detectable in patient blood. The 12-amino-acid insertion also enhanced the genome maturity of secreted virus particles, possibly through less efficient envelopment of core particles. Cotransfection of genotypes G and A did not lead to mutual interference of genome replication or virion secretion. Considering that HBeAg is an immunotolerogen required for the establishment of persistent infection, its lack of expression rather than a replication defect could be the primary determinant for the rare occurrence of genotype G monoinfection.

Emerging drugs for hepatitis B.

Abstract: Chronic hepatitis B remains a treatment challenge despite the availability of new nucleoside analogs. This is due to the persistence of viral infection during therapy, which exposes the patient to the risk of developing antiviral drug resistance. Therefore, new polymerase inhibitors are needed to manage resistance to existing drugs and new trials of combination therapy are required to delay drug resistance. In the future, antiviral agents targeting other steps of the viral life cycle will be needed to achieve antiviral synergy and prevent antiviral drug resistance. Immune modulators are also expected to enhance antiviral response and to achieve sustained response. Discovery of new antiviral drugs and design of new treatment strategies are, therefore, needed to manage this disease, which is still the main cause of cirrhosis and hepatocellular carcinoma worldwide.

Hepatitis B Virus Drug Resistance and Combination Therapy

Abstract: Despite the development of new nucleoside analogs, antiviral therapy of chronic hepatitis B remains a major clinical challenge. Indeed, because of both viral genome persistence and hepatitis B virus genome heterogeneity, these antivirals may select for drug-resistant mutants. The development of drug resistance is associated with liver disease progression. The progress made in virologic assays also allows a better monitoring of antiviral therapy, which enables an early treatment adaptation based on the knowledge of cross resistance between antivirals before clinical deterioration. The management of antiviral drug resistance relies on the addition of a second drug having a complementary cross-resistance profile. This has evolved towards earlier intervention at the time of virologic breakthrough, and currently it is even recommended to adapt antiviral treatment in case of incomplete viral load suppression during the first year of therapy. The concept of de novo combination therapy to significantly prevent the delay of the occurrence of hepatitis B virus drug resistance is discussed and awaits confirmation by clinical trials. (Hepatology Rev. 2007;4:34-47)