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F Zoulim

Publications and source records attributed to F Zoulim.

At least 37 records · Page 2Linked to original sources
PubMed2001

Sequential treatment with lamivudine and interferon monotherapies in patients with chronic hepatitis B not responding to interferon alone: results of a pilot study.

Sustained viral suppression using monotherapy with interferon alfa (IFN-alpha) or lamivudine can only be achieved in a small percentage of patients with chronic hepatitis B. The concomitant administration of lamivudine and IFN-alpha does not enhance efficacy. We postulated that the optimal timing of therapy might be sequential treatment with lamivudine and IFN-alpha. The aim of this study was therefore to assess the efficacy of sequential treatment in patients resistant to IFN-alpha alone. Fourteen male patients, with a median age of 40 years, nonresponders to IFN-alpha with hepatitis B virus (HBV) DNA > 100 pg/mL (branched DNA [bDNA] Chiron) and positive hepatitis B e antigen (HBeAg) in 11 of 14 patients, were treated with lamivudine 100 mg/d alone for 20 weeks, then with both IFN-alpha2b 5 MU 3 times per week and lamivudine for 4 weeks, and lastly with IFN-alpha alone for 24 weeks. At the end of lamivudine therapy, all patients had undetectable serum HBV DNA, and none exhibited an emergence of HBV polymerase mutant or breakthrough. Sustained serum HBV-DNA clearance 6 months after the end of sequential treatment was achieved in 8 of 14 patients, HBeAg-to-anti-HBe seroconversion in 5 of 11 patients, and HBeAg and hepatitis B surface antigen (HBsAg) seroconversions in 3 of 14 patients (anti-HBs > 100 IU/mL). All sustained responders had normalized their alanine transaminase (ALT) values and exhibited histologic improvements. In conclusion, the results of this pilot study suggest that sequential treatment with lamivudine and IFN-alpha can induce a sustained virologic response, including HBs seroconversion, in patients with chronic hepatitis B not responding to IFN-alpha alone, without the selection of drug-resistant mutants. This therapeutic schedule warrants further evaluation in clinical trials.

Adult↗
PubMed2001

Antiviral activity of beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine in woodchucks chronically infected with woodchuck hepatitis virus.

The L-nucleoside analog beta-L-2',3'-dideoxy-2',3'-didehydro-5-fluorocytidine (beta-L-Fd4C) was first shown to exhibit potent activity against hepatitis B virus (HBV) in tissue culture and then to significantly inhibit viral spread during acute infection in the duck HBV model (F. Le Guerhier et al., Antimicrob. Agents Chemother. 44:111-122, 2000). We have therefore examined its antiviral activity in a mammalian model of chronic HBV infection, the woodchuck chronically infected with woodchuck hepatitis virus (WHV). Side-by-side comparison of beta-L-Fd4C and lamivudine administered intraperitoneally during short-term and long-term protocols demonstrated a more profound inhibition of viremia in beta-L-Fd4C-treated groups. Moreover, beta-L-Fd4C induced a marked inhibition of intrahepatic viral DNA synthesis compared with that induced by lamivudine. Nevertheless, covalently closed circular (CCC) DNA persistence explained the lack of clearance of infected hepatocytes expressing viral antigens and the relapse of WHV replication after drug withdrawal. Liver histology showed a decrease in the inflammatory activity of chronic hepatitis in woodchucks receiving beta-L-Fd4C. An electron microscopy study showed the absence of ultrastructural changes of hepatic mitochondria, biliary canaliculi, and bile ducts. However, a loss of weight was observed in all animals, whatever the treatment, as was a transient skin pigmentation in all woodchucks during beta-L-Fd4C treatment. There was no evidence that lamivudine or beta-L-Fd4C could prevent the development of hepatocellular carcinoma with the protocols used. These results indicate that beta-L-Fd4C exhibits a more potent antiviral effect than lamivudine in the WHV model but was not able to eradicate CCC DNA and infected cells from the liver at the dosage and with the protocol used.

Animals↗
PubMed2001

Current management strategies for hepatitis B in the elderly.

Despite the availability of an efficient vaccine, chronic hepatitis B virus (HBV) infection remains a major public health problem worldwide. The World Health Organization estimates that there are still 350 million chronic carriers of the virus who are at risk of developing chronic hepatitis, liver cirrhosis and hepatocellular carcinoma (HCC). Antiviral therapy consists of the administration of either interferon-alpha (IFN alpha) or lamivudine. In the elderly, specific issues should be addressed. Because of the long duration of viral infection, screening for HCC is warranted in these patients, as new therapeutic options are being developed. Antiviral treatment for chronic hepatitis B is indicated in patients with elevated transaminases, the presence of HBV replication, and inflammatory activity on liver histology analysis, providing the patient has no other serious health problem impacting on life expectancy. Since IFN alpha therapy may cause many general adverse effects, lamivudine may be the best current treatment option in this patient population. The pharmacokinetics of lamivudine in the elderly are slightly different from those in younger adults but this does not require dose adjustment, except in the presence of renal function impairment. However, the beneficial effects of lamivudine therapy must be weighed against the selection of drug-resistant mutants. New therapeutic strategies are now under evaluation and may be available in the future for the elderly population. Besides mass HBV vaccination programmes, people sharing a house with patients infected with HBV should be vaccinated to prevent viral transmission.

Aged↗
PubMed2001

Evaluation of novel strategies to combat hepatitis B virus targetting wild-type and drug-resistant mutants in experimental models.

Recent studies have shown that the kinetics of hepatitis B virus (HBV) clearance during antiviral therapy are slow, requiring long-term therapy to control viral replication. It has also been shown that emergence of resistant mutants is accelerated by high HBV replication and hepatocyte turnover, which are common features in patients with chronic HBV infection. It is therefore important to continue research on novel antiviral agents to design optimal combination strategies. The duck and woodchuck models of hepadnavirus infection are currently the best models for the investigation of the inhibitory effect of nucleoside analogues on wild-type and lamivudine-resistant mutants. Our studies revealed that these mutants have a decreased priming and elongation activity, and remain sensitive to novel nucleoside analogues. Tissue culture experiments with transient transfection of wild-type and mutant viruses also confirmed these data. Infection studies in primary hepatocytes and in animal models gave insight into the pathobiology of lamivudine-resistant mutants, as well as into the kinetics of wild-type virus clearance during antiviral therapy. Furthermore, it appears that novel strategies inducing a specific anti-HBV immune response by a DNA vaccine approach may induce viral clearance. Altogether, these results suggest that: (i) lamivudine-resistant mutants are likely to be cross-resistant to other L-cytidine analogues; (ii) antiviral therapy using a single reverse transcriptase (RT) inhibitor is likely to fail to eradicate viral covalently closed circular DNA; and (iii) new nucleoside analogues with unique mode of action (inhibition of priming or elongation of RT, or DNA polymerase activity) and activity against lamivudine-resistant strains are emerging. Combination of these new anti-HBV agents with DNA based immunization may prove useful to eradicate viral infection.

Animals↗
PubMed2000

[Hepatitis C virus].

Hepatitis C virus (HCV) is a small enveloped virus whose genome is a RNA molecule encoding a polyprotein that is processed by cellular and viral proteases to produce the 3 structural proteins (the core protein C and the 2 envelope proteins E1 and E2) and the 6 nonstructural proteins (NS2, NS3, NS4A, NS4B, NS5A and NS5B). The HCV genome exhibits a significant genetic heterogeneity. HCV isolates can be divided into genetically distinct groups referred to as genotypes, whereas the population of HCV genomes, within an infected individual, is present as a group of heterogeneous but closely related sequences referred to as quasi-species. Studies of the molecular biology of HCV and of new vaccinal or therapeutic strategies are hampered by the lack of easy to use cellular culture systems and of animal models.

Animals↗
PubMed2000

Evolution of hepatitis B virus polymerase gene sequence during famciclovir therapy for chronic hepatitis B.

Prolonged administration of nucleoside analogues for chronic hepatitis B may result in the emergence of hepatitis B viral polymerase mutants. To gain insight into the mechanism involved in the virus's resistance to famciclovir, the amino acid sequences of the terminal protein and reverse-transcriptase (RT) domains of the viral polymerase were determined during therapy among 28 patients. The antiviral response was independent of viral genotypes, and nonresponse to famciclovir was associated with a complex variability of the RT domain. No mutation in the YMDD motif was observed, whereas an L528M mutation was clearly selected by famciclovir treatment in 2 patients, as well as 14 novel mutations in 7 patients. Clone sequence analysis of the RT domains of patients undergoing retreatment with famciclovir and/or lamivudine showed the selection of a preexisting drug-resistant mutant in one case and indicated that sequential antiviral therapy may allow the rapid selection of resistant strains.

2-Aminopurine↗
PubMed2000

Persistence of viral replication after anti-HBe seroconversion during antiviral therapy for chronic hepatitis B.

BACKGROUND/AIMS: Hepatitis B virus genome mutants may be selected during the immune-mediated clearance of infection or during long-term nucleoside analog administration and may escape both antiviral pressures. The pattern of anti-HBe seroconversion was analyzed in patients receiving new nucleoside analogs, lamivudine or famciclovir, in comparison with patients treated with interferon alpha. METHODS: Eighteen consecutive patients who seroconverted to anti-HBe were included in the study. Serial serum samples were studied with the quantitative determination of HBV DNA by the branched DNA assay (Chiron) and by a quantitative PCR assay (Roche diagnostics), determination of pre-S1 Ag, the genetic analysis of the viral genome with the determination of pre-core promoter or pre-core region mutations with a line probe assay (Innogenetics) and, in selected samples of polymerase gene mutations. RESULTS: The quantitative PCR assay was found to be more sensitive than the bDNA assay, allowing a 25-log decrease in viral DNA levels to be demonstrated after anti-HBe seroconversion. Viral persistence after anti-HBe seroconversion induced by interferon, lamivudine or famciclovir, was often associated with circulating HBV genomes harboring mutations in the precore promoter. The clinical significance of these findings was demonstrated by the observation of reversion to HBeAg in two patients treated with interferon and one with lamivudine. CONCLUSION: Persistence of significant levels of viremia that are not detected by the branched DNA assay may be observed after anti-HBe seroconversion. A precise monitoring of viremia levels with more sensitive assays and HBV mutant strains is warranted in patients undergoing antiviral therapy.

2-Aminopurine↗
PubMed2000

Rapid detection of genotypes and mutations in the pre-core promoter and the pre-core region of hepatitis B virus genome: correlation with viral persistence and disease severity.

BACKGROUND/AIMS: We aimed to clarify the clinical relevance of hepatitis B virus pre-core mutant detection in patients with chronic hepatitis B using a newly developed assay. METHODS: Viral genotypes and pre-core mutations were studied in relation to viral persistence and liver disease severity using INNO-LiPA methodology. The study group included 151 patients with chronic hepatitis B, 85 positive for HBeAg (group I) and 66 positive for anti-HBe (group II). RESULTS: The prevalence of viral genotypes in group I was: 64% A, 1% B, 15% C, 19% D, 0% E, 0% F and in group II: 39% A, 0% B, 2% C, 56% D, 2% E, 2% F (p<0.001). The prevalence of mutations at pre-core codon 28 (M2) was lower in group I (5%) than in group II (64%) (p<0.001). The prevalence of pre-core promoter mutations was also lower in group I (21%) than in group II (61%) (p<0.001). M2 mutations were more frequently detected in genotype D than in genotype A (p<0.001), while the other mutations were not influenced by viral genotype. Serum HBV DNA levels were significantly lower in group II versus group I (p<0.001), and in patients with any of the pre-core mutations versus wild-type sequence (p<0.01). Although cirrhosis was more frequent in group II (37%) versus group I (22%) and in patients with either one of the pre-core mutation (31%) versus wild-type sequence (25%), there was no statistical difference in liver severity assessed by ALT levels and Knodell score. CONCLUSION: Pre-core mutants, whose molecular pattern is strongly dependent on viral genotypes, are associated with viral persistence in anti-HBe positive patients with ongoing chronic hepatitis B. The availability of this rapid assay should allow a precise monitoring of viral pre-core mutants during the course of chronic hepatitis B.

Adolescent↗
PubMed2000

Early detection of viral resistance by determination of hepatitis B virus polymerase mutations in patients treated by lamivudine for chronic hepatitis B.

We have analyzed the molecular dynamics of emergence of drug-resistant strains in patients receiving lamivudine therapy for chronic hepatitis B. Twenty consecutive patients with lamivudine resistance were studied (13 hepatitis B e antigen [HBeAg]-positive patients and 7 HBe antibody [anti-HBe]-positive patients). Determination of viral genotype, precore mutants, and polymerase gene mutants (L528M, M552V, M552I) was performed using the research version of Lipa-HBV. Quantitative analysis of HBV DNA was performed using both branched DNA (bDNA) and polymerase chain reaction (PCR) assays. Polymerase mutants (genotypic resistance) were found in 16 of 20 patients. Genotypic resistance was detected earlier than the phenotypic resistance (P =.004). Quantitative PCR allowed detection of viral DNA throughout the entire study period in 16 of 20 patients. Analysis of pretreatment variables showed that high alanine transaminase (ALT) levels (>3 x the upper limit of normal [ULN]) was associated with a more rapid selection of drug-resistant mutants (P =.027) and a high hepatitis B virus (HBV) DNA level (>1,497 Meq/mL, bDNA) with a more rapid occurrence of phenotypic resistance (P =.04). At the time of viral breakthrough, the mean serum HBV-DNA values were not different from the pretreatment values (P =.37). ALT levels were higher in anti-HBe-positive patients compared with pretreatment values and to HBeAg-positive patients (P =.01). In 8 patients, antiviral therapy was modified after viral breakthrough, with the introduction of famciclovir and/or interferon alfa. Viral DNA became undetectable by bDNA in 3 patients who received interferon. Our results suggest that genotypic assays for polymerase mutant detection and quantitative determination of viremia with highly sensitive assay are warranted for an optimal monitoring of antiviral therapy of chronic hepatitis B.

2-Aminopurine↗
PubMed2000

A new genotype of hepatitis B virus: complete genome and phylogenetic relatedness.

The hepatitis B virus (HBV) genotype was determined in a total of 121 plasma samples collected in France and the US from patients chronically infected with HBV. HBV genotype A was predominant in this collection, appearing in 66 samples (54%), while genotypes B, C, D, E and F occurred in 4 (3%), 14 (12%), 23 (19%), 1 (1%) and 0 (0%) of samples, respectively. However, the genotype of a total of 13 (11%) samples (2 from France, 11 from the US) could not be determined with the methodology used. Sequence analysis, and subsequent phylogenetic analysis of the complete genome and the individual open reading frames, showed that the virus isolate from these samples was 3248 bp long and, phylogenetically, did not cluster with any of the known genotypes. This strain was provisionally called HBV genotype G. Virus isolates that were obtained from geographically separated regions like France and the US were closely related to each other. All virus strains analysed contained some characteristic differences when compared to genotype A: a translational stop codon at aa 2 and 28 of the preCore region; a 36 nt (12 aa) insert in the amino-terminal part of the Core antigen (HBcAg); a 2 aa deletion in the carboxy-terminal part of HBcAg; and a 1 aa deletion in the preS1 open reading frame. The deduced amino acid sequence of HBsAg suggests that this newly discovered genotype G strain belongs to serological group adw2.

Amino Acid Sequence↗
PubMed2000

Characterization of the antiviral effect of 2',3'-dideoxy-2', 3'-didehydro-beta-L-5-fluorocytidine in the duck hepatitis B virus infection model.

A novel L-nucleoside analog of deoxycytidine, 2',3'-dideoxy-2', 3'-didehydro-beta-L-5-fluorocytidine (beta-L-Fd4C), was recently shown to strongly inhibit hepatitis B virus (HBV) replication in the 2.2.15 cell line. Therefore, its antiviral activity was evaluated in the duck HBV (DHBV) infection model. Using a cell-free system for the expression of the DHBV polymerase, beta-L-Fd4C-TP exhibited a concentration-dependent inhibition of dCTP incorporation into viral minus-strand DNA with a 50% inhibitory concentration of 0.2 microM which was lower than that of other tested deoxycytidine analogs, i.e. , lamivudine-TP, ddC-TP, and beta-L-FddC-TP. Further analysis showed that beta-L-Fd4C-TP is likely to be a competitive inhibitor of dCTP incorporation and to cause premature DNA chain termination. In primary duck hepatocyte cultures infected in vitro, beta-L-Fd4C administration exhibited a long-lasting inhibitory effect on viral DNA synthesis but could not clear viral covalently closed circular DNA (CCC DNA). Results of short-term antiviral treatment in experimentally infected ducklings showed that beta-L-Fd4C exhibited the most potent antiviral effect, followed by beta-L-FddC, lamivudine, and ddC. Longer administration of beta-L-Fd4C induced a sustained suppression of viremia (>95% of controls) and of viral DNA synthesis within the liver. However, the persistence of trace amounts of viral CCC DNA detected only by PCR was associated with a recurrence of viral replication after drug withdrawal. In parallel, beta-L-Fd4C treatment suppressed viral antigen expression within the liver and decreased intrahepatic inflammation and was not associated with any sign of toxicity. Our data, therefore, demonstrate that in the duck model of HBV infection, beta-L-Fd4C is a potent inhibitor of DHBV reverse transcriptase activity in vitro and suppresses viral replication in the liver in vivo.

Animals↗
PubMed2000

Line probe assay for monitoring drug resistance in hepatitis B virus-infected patients during antiviral therapy.

Since the introduction of antiviral compounds such as lamivudine and famciclovir in the treatment schedules of patients with chronic hepatitis B virus (HBV) infection, the accumulation of a variety of mutations in the HBV polymerase gene has been observed. The selection of these mutations is generally considered the cause of viral nonresponsiveness and treatment failure. Therefore, the detection of these mutations is of clinical importance. Previously genotyped HBV strains isolated from treated and untreated patients were amplified with primers specific for the HBV polymerase region from amino acids 465 to 562. Amplified products were cloned into plasmid vectors. The clones were used as reference strains. A set of 38 highly specific oligonucleotide probes covering three different codon positions, L528M, M552V/I, and V/L/M555I, were selected. These probes were applied as 19 different lines on a membrane strip. The strips were then hybridized with PCR fragments from the reference panel, revealing the amino acids at the three codon positions simultaneously for each clone. PCR products generated from two patients infected with HBV genotypes A and C, respectively, and treated with nucleoside analogs were analyzed on these strips. A gradual increase in genetic HBV polymerase complexity was observed in follow-up samples compared to that in pretreatment samples. Additional analysis of HBV polymerase DNA fragments in recombinant plasmid clones demonstrated the existence of (i) clones with double mutations, (ii) clones with single mutations at either codon 528, 552, or 555, and (iii) the simultaneous occurrence of two or more viral populations within one sample. This line probe assay detected the complex quasispecies nature of HBV and provided some insight into the dynamics of resistance mutations.

Amino Acid Sequence↗
PubMed2000

Design and evaluation of hepatitis B virus inhibitors.

Antiviral therapy of chronic hepatitis B remains a major clinical problem worldwide. The design of new nucleoside analogs that inhibit hepatitis B virus (HBV) replication allowed their evaluation in in vitro and in vivo experimental models of HBV infection. This research has led to the discovery of the anti-HBV activity of lamivudine and its approval for the therapy of chronic hepatitis B. However, due to the development of viral resistance, strategies based on the combination of new inhibitors of HBV replication with immune modulatory approaches are urgently required.

Animals↗
PubMed1999

Transient selection of a hepatitis B virus polymerase gene mutant associated with a decreased replication capacity and famciclovir resistance.

Prolonged therapy for chronic hepatitis B (HBV) with nucleoside analogs may result in the emergence of HBV mutants resistant to antivirals. Here, we describe the transient selection of an HBV polymerase gene mutant that was associated with viral persistence in an immune competent patient treated with famciclovir. Viral polymerase gene sequence was analyzed directly on polymerase chain reaction (PCR) products and also after cloning. The results showed the transient selection of a V542I mutant in the C domain of the viral polymerase. This mutation was associated with a stop codon at amino acid position 199 in the overlapping S gene. The mutated sequence was subcloned in a vector expressing the entire HBV pregenome to study its replication capacity after transient transfection in cultured hepatoma cells. The results showed that the V542I mutant has a decreased replication capacity compared with wild type virus and does not produce HBsAg. The sensitivity of the V542I mutant to penciclovir, the active metabolite of famciclovir, was further studied in tissue culture. This mutant was shown to be resistant to penciclovir, but remained sensitive to lamivudine, as was subsequently observed in vivo. These findings indicate that a prolonged administration of famciclovir may allow for the selection of HBV polymerase gene mutants in immune competent patients. The impaired replication capacity of this V542I mutant may have contributed to the absence of outgrowth of this viral strain in vivo. The study of the in vitro sensitivity of HBV polymerase mutants to nucleoside analogs will be important to design new anti-HBV strategies.

2-Aminopurine↗