Lamivudine resistance in hepatitis B: mechanisms and clinical implications

Design and Synthesis of Hepatitis B Virus (HBV) Capsid Assembly Modulators and Evaluation of Their Activity in Mammalian Cell Model

Capsid assembly modulators (CAMs) have emerged as a promising class of antiviral agents. We studied the effects of twenty-one newly designed and synthesized CAMs including heteroaryldihydropyrimidine compounds (HAPs), their analogs and standard compounds on hepatitis B virus (HBV) capsid assembly. Cytoplasmic expression of the HBV core (HBc) gene driven by the exogenously delivered recombinant alphavirus RNA replicon was used for high level production of the full-length HBc protein in mammalian cells. HBV capsid assembly was assessed by native agarose gel immunoblot analysis, electron microscopy and inhibition of virion secretion in HepG2.2.15 HBV producing cell line. Induced fit docking simulation was applied for modelling the structural relationships of the synthesized compounds and HBc. The most efficient were the HAP class compounds—dihydropyrimidine 5-carboxylic acid n-alkoxyalkyl esters, which induced the formation of incorrectly assembled capsid products and their accumulation within the cells. HBc product accumulation in the cells was not detected with the reference HAP compound Bay 41-4109, suggesting different modes of action. A significant antiviral effect and substantially reduced toxicity were revealed for two of the synthesized compounds. Two new HAP compounds revealed a significant antiviral effect and a favorable toxicity profile that allows these compounds to be considered promising leads and drug candidates for the treatment of HBV infection. The established alphavirus based HBc expression approach allows for the specific selection of capsid assembly modulators directly in the natural cell environment.

Role of tenofovir disoproxil fumarate in prevention of perinatal transmission of hepatitis B virus from mother to child: a systematic review and meta-analysis

BACKGROUND/AIMS

To prevent the perinatal transmission of hepatitis B virus (HBV) from mother to child, administration of an antiviral agent during pregnancy has been attempted in women who are either hepatitis B e antigen positive or have a high viral load. In this systematic review and meta-analysis with randomized controlled trials, we analyzed the efficacy and safety of tenofovir disoproxil fumarate (TDF) in preventing the perinatal transmission of HBV in pregnant women who have high HBV DNA titers.

METHODS

Multiple comprehensive databases (PubMed, EMBASE, and Cochrane databases) were searched for studies evaluating the efficacy of TDF for the prevention of perinatal transmission of HBV.

RESULTS

Two studies (one open label study and one double blind study) were included and analyzed. Intention-to-treat analysis (527 pregnancies) showed that the preventive effect of TDF was not significant (odds ratio [OR], 0.53; 95% confidence interval [CI], 0.13 to 2.17; p = 0.38, I2 = 81%). However, the per-protocol analysis showed that TDF significantly reduced perinatal transmission (OR, 0.10; 95% CI, 0.01 to 0.77; p = 0.03, I2 = 0%). There was no significant difference between the TDF group and the control group with respect to maternal and fetal safety outcomes.

CONCLUSION

In pregnant women who have high HBV DNA titers, TDF can reduce the perinatal transmission from mother to child without significant adverse events.

Cell Penetrating Peptides Used in Delivery of Therapeutic Oligonucleotides Targeting Hepatitis B Virus

Peptide Nucleic Acid (PNAs) and small noncoding RNAs including small interfering RNAs (siRNAs) represent a new class of oligonucleotides considered as an alternative therapeutic strategy in the chronic hepatitis B treatment. Indeed, chronic hepatitis B virus (HBV) infection remains a major public health problem worldwide, despite the availability of an effective prophylactic vaccine. Current therapeutic approaches approved for chronic HBV treatment are pegylated-interferon alpha (IFN)-α and nucleos(t)ide analogues (NAs). Both therapies do not completely eradicate viral infection and promote severe side effects. In this context, the development of new effective treatments is imperative. This review focuses on antiviral activity of both PNAs and siRNAs targeting hepatitis B virus. Thus, we briefly present our results on the ability of PNAs to decrease hepadnaviral replication in duck hepatitis B virus (DHBV) model. Interestingly, other oligonucleotides as siRNAs could significantly inhibit HBV antigen expression in transient replicative cell culture. Because the application of these oligonucleotides as new antiviral drugs has been hampered by their poor intracellular bioavailability, we also discuss the benefits of their coupling to different molecules such as the cell penetrating peptides (CPPs), which were used as vehicles to deliver therapeutic agents into the cells.

A systematic review of hepatitis B virus (HBV) drug and vaccine escape mutations in Africa: A call for urgent action

International sustainable development goals for the elimination of viral hepatitis as a public health problem by 2030 highlight the pressing need to optimize strategies for prevention, diagnosis and treatment. Selected or transmitted resistance associated mutations (RAMs) and vaccine escape mutations (VEMs) in hepatitis B virus (HBV) may reduce the success of existing treatment and prevention strategies. These issues are particularly pertinent for many settings in Africa where there is high HBV prevalence and co-endemic HIV infection, but lack of robust epidemiological data and limited education, diagnostics and clinical care. The prevalence, distribution and impact of RAMs and VEMs in these populations are neglected in the current literature. We therefore set out to assimilate data for sub-Saharan Africa through a systematic literature review and analysis of published sequence data, and present these in an on-line database (https://livedataoxford.shinyapps.io/1510659619-3Xkoe2NKkKJ7Drg/). The majority of the data were from HIV/HBV coinfected cohorts. The commonest RAM was rtM204I/V, either alone or in combination with associated mutations, and identified in both reportedly treatment-naïve and treatment-experienced adults. We also identified the suite of mutations rtM204V/I + rtL180M + rtV173L, that has been associated with vaccine escape, in over 1/3 of cohorts. Although tenofovir has a high genetic barrier to resistance, it is of concern that emerging data suggest polymorphisms that may be associated with resistance, although the precise clinical impact of these is unknown. Overall, there is an urgent need for improved diagnostic screening, enhanced laboratory assessment of HBV before and during therapy, and sustained roll out of tenofovir in preference to lamivudine alone. Further data are needed in order to inform population and individual approaches to HBV diagnosis, monitoring and therapy in these highly vulnerable settings.

Utilization of hepatitis B core antibody positive grafts in living donor liver transplantation

BACKGROUND

Utilization of liver grafts from hepatitis B core antibody (anti-HBc) positive donors carries the risk of reactivation of hepatitis B virus (HBV) in recipients because of post-transplant immunosuppressive therapy.

METHODS

This was a retrospective study of patients who had received liver grafts from anti-HBc positive live donors between 2006 and 2016 at our institute.

RESULTS

Out of 22 recipients [all males, mean age 45.4 years (range 18-64 years)], four patients were hepatitis B surface antigen (HBsAg) positive preoperatively and received entecavir post-transplantation. One among these patients who temporarily stopped entecavir had a recurrence of hepatitis B 39 months post-transplantation. Among the 13 non-immune [hepatitis B surface antibody (anti-HBs) < 10 mIU/mL] recipients, eight were prescribed lamivudine (100 mg daily) as monoprophylaxis. Four compliant patients remain negative for HBV so far. Out of the remaining four, two died secondary to sepsis unrelated to hepatitis B; two were non-compliant and developed reactivation of hepatitis B. Lamivudine was missed out in five non-immune patients; three of them developed hepatitis B reactivation while two remain negative. Anti-HBs titer was immune in five patients. Over a period of 4 to 8 years follow up, three remain immune without prophylaxis, while two expired due to causes unrelated to hepatitis B. Following the detection of hepatitis B infection, five patients have been started on tenofovir 300 mg once daily.

CONCLUSIONS

Anti-HBc positive liver grafts can be safely used for live donor liver transplantation. If the recipients are immune preoperatively, they can be merely followed up without HBV prophylaxis. However, it is extremely important to prophylactically treat the non-immune recipients with an antiviral agent lifelong.

Single-virion sequencing of lamivudine-treated HBV populations reveal population evolution dynamics and demographic history

BACKGROUND

Viral populations are complex, dynamic, and fast evolving. The evolution of groups of closely related viruses in a competitive environment is termed quasispecies. To fully understand the role that quasispecies play in viral evolution, characterizing the trajectories of viral genotypes in an evolving population is the key. In particular, long-range haplotype information for thousands of individual viruses is critical; yet generating this information is non-trivial. Popular deep sequencing methods generate relatively short reads that do not preserve linkage information, while third generation sequencing methods have higher error rates that make detection of low frequency mutations a bioinformatics challenge. Here we applied BAsE-Seq, an Illumina-based single-virion sequencing technology, to eight samples from four chronic hepatitis B (CHB) patients - once before antiviral treatment and once after viral rebound due to resistance.

RESULTS

With single-virion sequencing, we obtained 248-8796 single-virion sequences per sample, which allowed us to find evidence for both hard and soft selective sweeps. We were able to reconstruct population demographic history that was independently verified by clinically collected data. We further verified four of the samples independently through PacBio SMRT and Illumina Pooled deep sequencing.

CONCLUSIONS

Overall, we showed that single-virion sequencing yields insight into viral evolution and population dynamics in an efficient and high throughput manner. We believe that single-virion sequencing is widely applicable to the study of viral evolution in the context of drug resistance and host adaptation, allows differentiation between soft or hard selective sweeps, and may be useful in the reconstruction of intra-host viral population demographic history.

Role of Cell-Penetrating Peptides in Intracellular Delivery of Peptide Nucleic Acids Targeting Hepadnaviral Replication

Peptide nucleic acids (PNAs) are potentially attractive antisense agents against hepatitis B virus (HBV), although poor cellular uptake limits their therapeutic application. In the duck HBV (DHBV) model, we evaluated different cell-penetrating peptides (CPPs) for delivery to hepatocytes of a PNA-targeting hepadnaviral encapsidation signal (ε). This anti-ε PNA exhibited sequence-specific inhibition of DHBV RT in a cell-free system. Investigation of the best in vivo route of delivery of PNA conjugated to (D-Arg)₈ (P1) showed that intraperitoneal injection to ducklings was ineffective, whereas intravenously (i.v.) injected fluorescein-P1-PNA reached the hepatocytes. Treatment of virus carriers with i.v.-administered P1-PNA resulted in a decrease in viral DNA compared to untreated controls. Surprisingly, a similar inhibition of viral replication was observed in vivo as well as in vitro in primary hepatocyte cultures for a control 2 nt mismatched PNA conjugated to P1. By contrast, the same PNA coupled to (D-Lys)₄ (P2) inhibited DHBV replication in a sequence-specific manner. Interestingly, only P1, but not P2, displayed anti-DHBV activity in the absence of PNA cargo. Hence, we provide new evidence that CPP-PNA conjugates inhibit DHBV replication following low-dose administration. Importantly, our results demonstrate the key role of CPPs used as vehicles in antiviral specificity of CPP-PNA conjugates.

ANTIVIRAL ACTIVITY OF DIANTHUS SUPERBUSN L. AGAINST HEPATITIS B VIRUS IN VITRO AND IN VIVO

Background:

Hepatitis is a viral infection of hepatitis B virus (HBV). Limitations of drug used in the management of it opens the interest related to alternative medicine. The given study deals with the antiviral activity of Dianthus superbusn L. (DSL) against HBV in vitro & in vivo.

Material and Methods:

In vitro study liver cell line HepG2.2.15 was used by transinfected it with HBV. Cytotoxicity stduy was performed by using different concentrations of DSL such as 50, 100, 200, 500 & 1000 μg/ml. Anti HBV activity of DSL was estimated by assesing the concentration of HBsAg and HbeAg in cell culture medium by using ELISA. Whereas in vivo study was performed on ducklings and antiviral activity of DSL (100, 200, 400 mg/kg) was confirmed by estimating the serum concentration of HBV DNA and histopathology study of hepatocytes in HBV infected ducklings.

Result:

Result of the study suggested that >500 μg/ml concentration of hydroalcoholic extract of DSL was found tobe cytotoxic. It was also observed that DSL significantly (p<0.05) reduces the concentration of antigenes in cell culture media as per the concentration and days of treatment dependent. Moreover in vivo study confirms the anti viral activity of DSL (200 & 400 mg/kg) as it significantly (p<0.05) decreases the serum concenetration of HBV DNA in HBV infected dukling compared to control group. Histopathology study was also reveals the hepatprotective effect of DSL in HBV infected ducklings.

Conclusion:

The given study concludes the antiviral activity DSL against HBV by in vitro and in vivo models.

Synthesis, characterization and biological activity of a niobium-substituted-heteropolytungstate on hepatitis B virus

To synthesise and characterize the polyoxometalate Cs₂K₄Na[SiW₉Nb₃O₄₀]·H₂O 1 for its anti-hepatitis B virus (HBV) properties by using the HepG2.2.15 cell. The methylthiazol tetrazolium assay was used to evaluate the growth inhibitory effect of Compound 1 on HepG2.2.15 cell. By using ELISA and real-time PCR, respectively, the presence of extracellular hepatitis B surface antigen (HBsAg), e antigen (HBeAg), and HBV DNA were measured. The levels of intracellular HBV DNA and mRNA were determined by using Southern blot or reverse-transcription-PCR, respectively. Intracellular distribution of antigen were measured by Western blot. A 1995 μmol/L concentration of the commercially-available hepatitis B drug, adefovir dipivoxil (ADV), was required to achieve 50% cytotoxicity against cultured cells (CC₅₀) by day nine; in contrast, only 1747 μmol/L of Compound 1 was required for the same result. Treatment of HepG2.2.15 cells with Compound 1 effectively suppress the secretion of HBV antigens and HBV DNA in a dose-dependent and time-dependent manner. IC₅₀ values were determined to be 80 μmol/L for HBsAg, 75 μmol/L for HBeAg and 3.72 μmol/L for supernatant HBV DNA at day nine post-exposure, as opposed to 266, 296, 30.09 μmol/L, respectively, for ADV. Intracellular HBV DNA, mRNA and antigen were also found to be decreased by Compound 1. The same dose of ADV yielded a significantly less robust inhibitory effect. Compound 1 can clear HBV from hepatic cells and may represent a therapeutic agent to treat HBV infection.

Hepatitis B virus genotyping among chronic hepatitis B patients with resistance to treatment with lamivudine in the City of Ribeirão Preto, State of São Paulo

INTRODUCTION

Lamivudine is a nucleoside analogue that is used clinically for treating chronic hepatitis B infection. However, the main problem with prolonged use of lamivudine is the development of viral resistance to the treatment. Mutations in the YMDD motif of the hepatitis B virus DNA polymerase gene have been associated with resistance to drug therapy. So far, there have not been many studies in Brazil reporting on genotype-dependent development of resistance to lamivudine. Thus, the aim of the present study was to determine the possible correlation between a certain genotype and increased development of resistance to lamivudine among chronic hepatitis B patients.

METHODS

HBV DNA in samples from 50 patients under lamivudine treatment was amplified by means of conventional PCR. Samples were collected at Hospital das Clínicas, FMRP-USP. The products were then sequenced and phylogenetic analysis was performed.

RESULTS

Phylogenetic analysis revealed that 29 (58%) patients were infected with genotype D, 20 (40%) with genotype A and one (2%) with genotype F. Mutations in the YMDD motif occurred in 20% of the patients with genotype A and 27.6% of the patients with genotype D.

CONCLUSIONS

Despite the small number of samples, our results indicated that mutations in the YMDD motif were 1.38 times more frequent in genotype D than in genotype A.

Efficacy of initial treatment with clevudine in naive patients with chronic hepatitis B

BACKGROUND/AIMS

Clevudine, a pyrimidine nucleoside analogue, has potent antiviral effects in patients with chronic viral hepatitis B (CHB). We report the efficacy of initial treatment with clevudine in naïve patients with CHB living in Daejeon and Chungcheong Province, South Korea.

METHODS

One hundred five adults with CHB were administered 30 mg of clevudine per day for an average of 51 weeks. We evaluated viral markers and liver biochemistry retrospectively every 3 months.

RESULTS

Alanine aminotransferase (ALT), aspartate aminotransferase (AST), and hepatitis B virus (HBV) DNA before the treatment were 184 ± 188 IU/L, 150 ± 138 IU/L, and 7.1 ± 1.2 log copies/mL, respectively. Undetectable rates (< 60 IU/mL) of DNA were 36.2%, 68.9%, 83.6%, 76.2%, and 75.8% at 12, 24, 36, 48, and 60 weeks, respectively. Seroconversion rates were 9.1%, 13.6%, 24.6%, 26.5%, and 26.1% and ALT normalization rates were 64.5%, 78.1%, 87.9%, 90.0% at 12, 24, 36, and 48 weeks, respectively. Six patients (5.7%) had a viral breakthrough.

CONCLUSIONS

Clevudine is a useful drug in the initial treatment of patients with CHB, with a potent antiviral effect and low incidence of viral breakthrough.

Response to adefovir or entecavir in renal allograft recipients with hepatitic flare due to lamivudine-resistant hepatitis B

We studied the effects of adefovir or entecavir in six kidney transplant recipients (mean age 45.7 +/- 7.8 yr) who developed hepatitic flare due to lamivudine-resistant hepatitis B virus (HBV) infection, with 18 months of follow-up. All patients had elevated alanine aminotransferase (ALT) levels and HBV DNA >10(5) copies/mL (median 2.15 x 10(8) copies/mL) at baseline. Serum creatinine and creatinine clearance levels were 137.8 +/- 59.7 mumol/L and 62.6 +/- 18.7 mL/min, respectively. Four patients were treated with adefovir and two with entecavir. Median HBV DNA decreased to 1.99 x 10(5) copies/mL (p = 0.028) after six months, 1.5 x 10(4) copies/mL (p = 0.043) after 12 months, and 7.35 x 10(4) copies/mL (p = 0.068) after 18 months of treatment. There was a corresponding improvement in ALT (34.5 +/- 19.1 U/L after 18 months, p = 0.029 compared with baseline). The rate of HBV DNA suppression was variable, and three patients took over six months for the viral load to decrease to <10(5) copies/mL. After 18 months, HBV DNA was <10(5) copies/mL in four patients and <10(2) copies/mL in one patient. Treatment was well-tolerated and renal function remained stable. We conclude that both adefovir and entecavir are effective in the treatment of lamivudine-resistant HBV in renal allograft recipients, and the reduction of HBV DNA to <10(5) copies/mL could be slow.

Proteomic analysis of cellular protein alterations using a hepatitis B virus-producing cellular model

Hepatitis B virus (HBV) is one of the major etiological factors responsible for acute and chronic liver disease and for the development of hepatocellular carcinoma (HCC). To determine the effects of HBV replication on host cell-protein expression, we utilized 2-DE and MS/MS analysis to compare and identify differentially expressed proteins between an HBV-producing cell line HepG2.2.15 and its parental cell line HepG2. Of the 66 spots identified as differentially expressed (+/- over twofold, p <0.05) between the two cell lines, 62 spots (corresponding to 61 unique proteins) were positively identified by MS/MS analysis. These proteins could be clearly divided into three major groups by cluster and metabolic/signaling pathway analysis: proteins involved in retinol metabolism pathway, calcium ion-binding proteins, and proteins associated with protein degradation pathways. Other proteins identified include those that function in diverse biological processes such as signal transduction, immune regulation, molecular chaperone, electron transport/redox regulation, cell proliferation/differentiation, and mRNA splicing. In summary, we profiled proteome alterations between HepG2.2.15 and HepG2 cells. The proteins identified in this study would be useful in revealing the mechanisms underlying HBV-host cell interactions and the development of HCC. This study can also provide some useful clues for antiviral research.

Lamivudine for the prevention of hepatitis B virus reactivation in hepatitis-B surface antigen (HBSAG) seropositive cancer patients undergoing cytotoxic chemotherapy

Hepatitis B virus (HBV) is one of the major causes of chronic liver disease worldwide. Cancer patients who are chronic carriers of HBV have a higher hepatic complication rate while receiving cytotoxic chemotherapy (CT) and this has mainly been attributed to HBV reactivation. In this study, cancer patients who have solid and hematological malignancies with chronic HBV infection received the antiviral agent lamivudine prior and during CT compared with historical control group who did not receive lamivudine. The objectives were to assess the efficacy of lamivudine in reducing the incidence of HBV reactivation, and diminishing morbidity and mortality during CT. Two groups were compared in this study. The prophylactic lamivudin group consisted of 37 patients who received prophylactic lamivudine treatment. The historical controls consisted of 50 consecutive patients who underwent CT without prophylactic lamivudine. They were followed up during and for 8 weeks after CT. The outcomes were compared for both groups. Of our control group (n= 50), 21 patients (42%) were established hepatitis. Twelve (24%) of them were evaluated as severe hepatitis. In the prophylactic lamivudine group severe hepatitis were observed only in 1 patient (2.7%) of 37 patients (p < 0.006). Comparison of the mean ALT values revealed significantly higher mean alanine aminotransferase (ALT) values in the control group than the prophylactic lamivudine group; 154:64 (p < 0.32). Our study suggests that prophylactic lamivudine significantly decreases the incidence of HBV reactivation and overall morbidity in cancer patients during and after immunosuppressive therapy. Further studies are needed to determine the most appropriate nucleoside or nucleotide analogue for antiviral prophylaxis during CT and the optimal duration of administration after completion of CT.

The Anti-hepatitis B Virus Activity of Boehmeria nivea Extract in HBV-viremia SCID Mice

Boehmeria nivea extract (BNE) is widely used in southern Taiwan as a folk medicine for hepato-protection and hepatitis treatment. In previous studies, we demonstrated that BNE could reduce the supernatant hepatitis B virus (HBV) DNA in HBV-producing HepG2 2.2.15 cells. In the present study, we established an animal model of HBV viremia and used it to validate the efficacy of BNE in vivo. In this animal model, serum HBV DNA and HBsAg were elevated in accordance with tumor growth. To evaluate the anti-HBV activity of BNE, HBV-viremia mice were built up after one subcutaneous inoculation of HepG2 2.2.15 tumor cells in severe combined immunodeficiency mice over 13 days. The levels of serum HBV DNA were elevated around 10(5)-10(6) copies per milliliter. Both oral and intraperitoneal administration of BNE were effective at inhibiting the production of HBsAg and HBV DNA, whereas tumor growth was not affected by all test articles. Intraperitoneal administration of BNE appeared to have greater potential to inhibit serum HBV DNA levels compared with oral administration under the same dosage. Notably, reduced natural killer cell activity was also observed after high dosage of BNE administration, and this correlated with reduced serum HBV DNA. In conclusion, BNE exhibited potential anti-HBV activity in an animal model of HBV viremia.

Antiviral prophylaxis for chemotherapy-induced reactivation of chronic hepatitis B virus infection

Chronic hepatitis B virus (HBV) carriers are at considerable risk of reactivation of HBV infection when undergoing chemotherapy or immunosuppressive therapy. Complications of HBV reactivation, including asymptomatic elevation of HBV DNA levels, acute hepatitis, acute liver failure, and delays or dose reductions in chemotherapy, are avoidable with appropriate prophylactic oral antiviral therapy. This article reviews evidence for and presents a grade A recommendation supporting primary prophylaxis among HBV carriers with lamivudine. The dose and duration of prophylaxis, risk of lamivudine resistance, and future directions of prophylactic therapy for HBV reactivation during chemotherapy are discussed. Recommendations are suggested based on expert opinion for prophylaxis with the combination of lamivudine plus adefovir or with entecavir as alternative antiviral strategies that substantially reduce or avoid the risk of HBV antiviral drug resistance.

Systematic review: lamivudine prophylaxis for chemotherapy-induced reactivation of chronic hepatitis B virus infection

BACKGROUND

Reactivation of hepatitis B virus infection in asymptomatic hepatitis B surface antigen carriers undergoing chemotherapy or immunosuppressive therapy is a well-documented and potentially fatal complication. Data supporting the use of lamivudine for primary prophylaxis have emerged, but its use remains controversial and is not standardized.

AIM

To review current randomized-controlled trials, randomized trials and prospective case series to provide a clinically applicable, evidence-based recommendation.

METHODS

The published literature was identified using a MEDLINE/PubMed search with secondary review of cited publications, and inclusion of all prospective studies.

RESULTS

In nine prospective trials and one randomized-controlled trial, the rate of hepatitis among subjects receiving lamivudine prophylaxis ranged from 0% to 20% (16 of 173, 9.2%), compared with 33-67% among controls. Of patients receiving prophylaxis, 0-24% (15 of 173, 8.7%) developed hepatitis B virus reactivation, compared with 29-56% of controls. Three reactivation-related mortalities were reported (one receiving prophylaxis, two controls). No patients withdrew secondary to toxicity or development of lamivudine-resistant mutations.

CONCLUSIONS

The available data show a four- to sevenfold decrease in the rate of hepatitis and hepatitis B virus reactivation in patients who receive lamivudine prophylaxis. It is thus recommended that all hepatitis B surface antigen carriers receive lamivudine, or a comparable anti-viral agent, as prophylaxis from the initiation of chemotherapy until at least 1 year following its completion.

Inhibition of hepatitis B virus production by Boehmeria nivea root extract in HepG2 2.2.15 cells

AIM: To explore the anti-hepatitis B virus (HBV) effects of Boehmeria nivea (B. nivea) root extract (BNE) by using the HepG2 2.2.15 cell model system.

METHODS: Hepatitis B surface antigen (HBsAg), hepatitis B virus e antigen (HBeAg), and HBV DNA were measured by using ELISA and real-time PCR, respectively. Viral DNA replication and RNA expression were determined by using Southern and Northern blot, respectively.

RESULTS: In HepG2 2.2.15 cells, HBeAg (60%, P < 0.01) and particle-associated HBV DNA (> 99%, P < 0.01) secretion into supernatant were significantly inhibited by BNE at a dose of 100 mg/L, whereas the HBsAg was not inhibited. With different doses of BNE, the reduced HBeAg was correlated with the inhibition of HBV DNA. The anti-HBV effect of BNE was not caused by its cytotoxicity to cells or inhibition of viral DNA replication and RNA expression.

CONCLUSION: BNE could effectively reduce the HBV production and its anti-HBV machinery might differ from the nucleoside analogues.

A novel accurate ACRS-PCR method with a digestion internal control for identification of wild type and YMDD mutants of hepatitis B virus strains

As a consequence of the point mutation in the YMDD motif of the hepatitis B virus (HBV) polymerase gene, lamivudine-resistant mutants have been reported in chronic hepatitis B patients who underwent lamivudine therapy. The objective of the study was to develop a novel accurate artificially created restriction site (ACRS) method with a digestion internal control for identification of YMDD, YIDD and YVDD HBV strains. Three conserved, specific and diagnostic primers introducing NdeI, SspI and AleI cleavage sites were designed in order to identify YMDD, YIDD and YVDD strains, respectively; while, their reverse primers also modified with the above recognition sites in order to enzyme correctness monitoring and false outcome avoiding. Thirty-two chronic hepatitis B patients who had taken lamivudine for 1-3 years and checked by the Inno-LiPA HBV DR kit, were evaluated by the ACRS method and then compared to sequencing data. The results of the ACRS method revealed the YMDD mutant strain in 20 patients, YMDD plus YIDD pattern in 1 patient, YMDD plus YVDD in 4 patients, the YIDD in 4 patients and mixed infection with each three strains in 1 patient. The sequencing and Inno-LiPA results were in agreement with the ACRS results. The novel ACRS method is a reliable, rapid and a cost-effective technique for determination of HBV strains with the wild type and YMDD mutant patterns.

Synthesis and the biological evaluation of 2-benzenesulfonylalkyl-5-substituted-sulfanyl-[1,3,4]-oxadiazoles as potential anti-hepatitis B virus agents

Current treatments for chronic hepatitis B virus (HBV) infection include the use of interferon-alpha and of nucleoside analogs lamivudine, adefovir and entecavir. However, the use of interferon-alpha has many side effects while that of nucleosidic inhibitors can lead to the emergence of resistant viruses. Hence, new drugs for the treatment of HBV infection are still highly desired. Oxadiazoles have been observed to exhibit antiviral activities against RNA viruses. In this study, a facile synthesis of 2-benzenesulfonylalkyl-5-substituted-sulfanyl-[1,3,4]-oxadiazoles is reported. The compounds were then evaluated for their anti-HBV activity. 1-[2-[5-(1-Benzenesulfonyl-propyl)-[1,3,4]oxadiazol-2-yl-sulfanyl]-ethyl]-4-(2-methoxy-phenyl)-piperazine (1i) was able to inhibit the expression of the viral antigens, HBsAg and HBeAg in a concentration-dependent manner with no cytotoxic effects and without any effects on the expression of viral transcripts. Concentration- and time-dependent reductions in virion production were also observed. The inhibition of virion production was comparable to that of lamivudine and EC(50) values of 1.63 and 2.96 microM were obtained for compound 1i and lamivudine, respectively. Thus, in addition to the antiviral effects on RNA viruses, oxadiazoles also have anti-HBV activities.

He Jie Tang in the treatment of chronic hepatitis B patients

AIM: To explore the effect of He Jie Tang (decoction for medication) on serum levels of T lymphocyte subsets, NK cell activity and cytokines in chronic hepatitis B patients.

METHODS: Eighty-five patients with chronic hepatitis B were divided randomly into two groups. Fifty patients in group I were treated with He Jie Tang (HJT) and 35 patients in group II were treated with combined medication. The levels of T-lymphocyte subsets (CD₃⁺, CD₄⁺, CD₈⁺), NK cell activity, cytokines (TNF-α, IL-8, sIL-2R) were observed before and after the treatment. Another 20 normal persons served as group 3.

RESULTS: The level of CD₄⁺ cells and NK cell activity were lower, whereas the level of CD₈⁺ cells in patients was higher than that in normal persons (t = 2.685, 3.172, and 2.754 respectively; P<0.01). The levels of TNF-α, IL-8, and sIL-2R in chronic hepatitis B patients were higher than those in normal persons (t = 3.526, 3.170, and 2.876 respectively; P<0.01). After 6 months of treatment, ALT, AST, and TB levels in the two groups were obviously decreased (t = 3.421, 3.106, and 2.857 respectively; P<0.01). The level of CD₄⁺ cells and NK cell activity were increased whereas the level of CD₈⁺ cells decreased (t = 2.179, 2.423, and 2.677 respectively; P<0.05) in group I. The levels of TNF-α, IL-8, and sIL-2R in group I were decreased significantly after the treatment (t = 2.611, 2.275, and 2.480 respectively; P<0.05) but had no significant difference in group II after the treatment (t = 1.906, 1.833, and 2.029 respectively; P>0.05). The total effective rate had no significant difference between the two groups (X² = 2.882, P>0.05) but the markedly effective rate was significantly different between the two groups (X² = 5.340, P<0.05).

CONCLUSION: HJT is effective in treating chronic hepatitis B. HJT seems to exert its effect by improving the cellular immune function and decreasing inflammatory cytokines in chronic hepatitis B patients. The function of HJT in protecting liver function in the process of eliminating virus needs to be further studied.

High replicative full-length lamivudine-resistant hepatitis B virus isolated during acute exacerbations

During chronic HBV infections, exacerbations of disease usually occur without clearly understood mechanisms. In this study, full-length HBV genomes were analyzed from four chronic hepatitis B patients who developed resistance to lamivudine [-2'-deoxy-3'-thiacytidine, LMV] accompanied by acute exacerbation of disease. Paired full-length HBV isolates were cloned from the sera of patients prior to LMV treatment and after drug resistant breakthrough isolates emerged with exacerbation. Compared to the isolates before treatment, isolates from all four patients during exacerbation showed marked increase in replicative competence by cell transfection study. Viral genome amplification and direct sequencing was used further to study the sequence differences between the dominant species and the clones used for functional analysis. Apart from mutations at the YMDD motif, no shared mutations were shown between all isolates. The isolates from the one patient who recovered from the exacerbation showed a lower number of mutations, and in particular, lacked basal core promoter (BCP) mutations at 1762/1764. In contrast, BCP mutations were found in isolates from the other three patients. Thus, in patients with acute exacerbation, high replicative strains might be selected from the total HBV quasispecies during treatment, and amongst these strains, those with core promoter mutations were most likely to be associated with severe clinical exacerbations.

Preliminary study on the efficacy and safety of lamivudine and interferon alpha therapy in decreasing serum HBV DNA level in HBV positive transgenic mice during pregnancy

Previous studies reported that the HBV DNA level in maternal serum is an important risk factor for intrauterine infection. Two antiviral drugs, lamivudine (3TC) and interferon alpha (IFNalpha), are used extensively clinically to reduce maternal HBV DNA level, However, because of a lack of evidence on the efficacy and safety of these drugs during pregnancy, they are categorized as grade C which prevents their use during pregnancy. This study provides new data on the efficacy and safety of lamivudine and IFNalpha in HBV positive transgenic pregnant mice. In this study, transgenic mice with high titers of hepatitis B virus (HBV) were employed to study the antiviral effects of 3TC and IFNalpha during different gestation periods. The study also examined changes in several serological HBV markers, the effects of perinatal exposure to antiviral drugs on the mother and offspring, drug efficacy in reducing the level of HBV DNA in maternal blood, and the safety to both the mother and offspring. The main conclusion of the study is that a significant decrease in HBV DNA level can be obtained after treatment with lamivudine but not with IFNalpha. No adverse effects were observed in the maternal mice and the offsprings. This finding may provide a rationale for the potential use of lamivudine for the treatment of pregnant women as a safe and effective measure to reduce the level of maternal viremia.

Oligonucleotide chip for detection of Lamivudine-resistant hepatitis B virus

Hepatitis B virus (HBV) is one of the major causes of liver disease worldwide. It is important to conduct antiviral therapy against chronic hepatitis B to minimize the amount of liver damage. Lamivudine has been known to be an effective antiviral agent for the treatment of HBV infection. However, the emergence of viral mutants resistant to lamivudine is the main concern during the treatment of HBV-infected patients. Therefore, the detection of lamivudine-resistant mutants is of clinical importance. We have developed an oligonucleotide chip for the detection of lamivudine-resistant HBV which is rapid and accurate. The oligonucleotide chip consists of quality control probes, negative control probes, and specific oligonucleotide probes for the detection of lamivudine-resistant HBV. The specific probes consist of five probes for the detection of wild-type rtL180, rtM204, and rtV207 sequences and seven probes for the detection of HBV mutations. We tested 123 serum samples from patients with chronic HBV infection who had received lamivudine therapy. Eighty samples contained mutants with YMDD mutations. Among these, 17 contained rtM204V (YVDD), 24 contained rtM204I3 (YIDD3), 3 contained rtM204I2 (YIDD2), and 36 contained mixed types. We compared the results obtained with our oligonucleotide chip with those obtained by PCR-restriction fragment length polymorphism (RFLP) analysis and sequencing. The rate of concordance between the assay with the oligonucleotide chip and PCR-RFLP analysis for detection of the YMDD motif was 96.7%. The rate of concordance between the results obtained with the oligonucleotide chip for the detection of rtL180 and rtV207 and the results obtained by sequencing was 100%. Thus, the oligonucleotide chip is a reliable and useful tool for the detection of antiviral-resistant HBV.

A new strategy for studying in vitro the drug susceptibility of clinical isolates of human hepatitis B virus

Resistance of hepatitis B virus (HBV) to antivirals has become a major clinical problem. Our objective was to develop a new method for the cloning of naturally occurring HBV genomes and a phenotypic assay capable of assessing HBV drug susceptibility and DNA synthesis capacity in vitro. Viral DNA was extracted from sera and was amplified by polymerase chain reaction, and amplicons were cloned into vectors that enable, after cell transfection, the initiation of the intracellular HBV replication cycle. Single or multiple clones were used to transfect Huh7 cells. The viral DNA synthesis capacity and drug susceptibility were determined by measuring the level of intracellular DNA intermediate, synthesized in absence or presence of antiviral, using Southern blot analysis. We have developed, calibrated, then used this phenotypic assay to determine the drug susceptibility of HBV quasispecies isolated throughout the course of therapy from patients selected according to their mutation profile. A multiclonal and longitudinal analysis enabled us to measure the variation of drug susceptibility of different viral quasispecies by comparison of IC(50)/IC(90)s with standards. The presence of famciclovir- or lamivudine-induced mutations in the viral population caused a change in viral DNA synthesis capacity and drug susceptibility in vitro, demonstrating the clinical relevance of the assay. In conclusion, our phenotypic assay enables the in vitro characterization of DNA synthesis capacity and drug susceptibility of HBV quasispecies isolated from patients. This assay should allow a better monitoring of patients undergoing antiviral therapy, as well as the screening of novel drugs on emerging resistant strains.

Superinfection exclusion in duck hepatitis B virus infection is mediated by the large surface antigen

Superinfection exclusion is the phenomenon whereby a virus prevents the subsequent infection of an already infected host cell. The Pekin duck hepatitis B virus (DHBV) model was used to investigate superinfection exclusion in hepadnavirus infections. Superinfection exclusion was shown to occur both in vivo and in vitro with a genetically marked DHBV, DHBV-ClaI, which was unable to establish an infection in either DHBV-infected ducklings or DHBV-infected primary duck hepatocytes (PDHs). In addition, exclusion occurred in vivo even when the second virus had a replicative advantage. Superinfection exclusion appears to be restricted to DHBV, as adenovirus, herpes simplex virus type 1, and vesicular stomatitis virus were all capable of efficiently infecting DHBV-infected PDHs. Exclusion was dependent on gene expression by the original infecting virus, since UV-irradiated DHBV was unable to mediate the exclusion of DHBV-ClaI. Using recombinant adenoviruses expressing DHBV proteins, we determined that the large surface antigen mediated exclusion. The large surface antigen is known to cause down-regulation of a DHBV receptor, carboxypeptidase D (CPD). Receptor down-regulation is a mechanism of superinfection exclusion seen in other viral infections, and so it was investigated as a possible mechanism of DHBV-mediated exclusion. However, a mutant large surface antigen which did not down-regulate CPD was still capable of inhibiting DHBV infection of PDHs. In addition, exclusion of DHBV-ClaI did not correlate with a decrease in CPD levels. Finally, virus binding assays and confocal microscopy analysis of infected PDHs indicated that the block in infection occurs after internalization of the second virus. We suggest that superinfection exclusion may result from the role of the L surface antigen as a regulator of intracellular trafficking.

Molecular epidemiology of hepatitis B and C virus infections in Asia

The present paper provides a review of the current literature regarding the molecular-based epidemiology of hepatitis B virus (HBV) and hepatitis C virus (HCV), which are very important viruses underlying the etiology of blood-borne infectious diseases worldwide. Particularly, both HBV and HCV are widespread on the Asian continent and are associated with acute and chronic liver diseases, including hepatocellular carcinoma. HBV has been classified into genotypes A through G and shown to have a distinct geographic distribution. In Asia, genotypes B and C of HBV prevail, and genotype C has been shown to cause more serious liver disease than genotype B. High prevalence of HBV mutants with various forms, such as the pre-S mutant, basal core promoter mutant, YMDD motif mutant and vaccine escape mutant, were seen in Asia and these were found to be related to the severity of liver disease and sensitivity to therapy. HCV has also been classified into multiple genotypes and associated with geographic distribution. HCV genotype 1 is less sensitive to interferon therapy and may be associated with the presence of more serious liver disease than the other genotypes. Data on the relation among the HBV/HCV genotypes, their pathogenicity in chronic liver diseases including hepatocellular carcinoma and their effect on therapy are awaited with great interest, especially in Asia, which is an endemic region of blood-borne hepatitis viruses.

Significance of the YMDD motif mutation of P gene of hepatitis B virus

AIM: To determine significance of the YMDD motif mutation of P gene of hepatitis B virus during lamivudine therapy for chronic hepatitis B and to provide guideline for the clinical treatment.

METHODS: Dynamic change of HBV DNA quantitation was measured with fluorescence quantitative PCR during lamivudine treatment. 40 patients from chronic hepatitis B were treated with lamivudine for 48 wks. In 17 patients HBV DNA remained to be positive, YMDD mutation were examined by GeneChip and Uniarray techniques.

RESULTS: In patients treated with lamivudine for 48 wks, HBV DNA turned negative in 23 cases (57.5%). In 17 patients HBV DNA remained to be positive, there was HBV DNA rebound in 8 patients during lamivudine treatment. There were YMDD mutations in 7 cases (5 cases from patients of HBV DNA rebound).The rate of YMDD mutation was 17.5% (7/40).

CONCLUSION: During lamivudine treatment, HBV YMDD in some patients can mutate. The HBV DNA rebound is associated with emergence of YMDD mutants. Detection of the YMDD motif mutation in P gene of hepatitis B virus is important to clinical treatment for chronic hepatitis B.

Effects of interferon, ribavirin, and iminosugar derivatives on cells persistently infected with noncytopathic bovine viral diarrhea virus

Persistent infection with hepatitis C virus (HCV) is a major cause of chronic hepatitis in humans. In chronic carriers, the viral infection induces liver damage that predisposes the patient for cirrhosis and can lead to hepatocellular carcinoma. Current chemotherapies are limited to alpha interferon (IFN-alpha) used either alone or in combination with ribavirin (RBV). In addition to its limited efficacy, this treatment is frequently poorly tolerated because of its side effects. The urgently needed development of new drugs is made difficult by the lack of an in vitro or in vivo infectivity model, and no cell line has been found so far to reliably and reproducibly support HCV infection. For this reason, the closely related pestivirus bovine viral diarrhea virus (BVDV) has sometimes been used as a surrogate in vitro infectivity model. In this study we used an MDBK cell line persistently infected with noncytopathic BVDV to assess the antiviral effect of IFN-alpha and RBV, the two drugs currently in clinical use against HCV. The same system was then used to evaluate the potential of two classes of iminosugar derivates to clear noncytopathic BVDV infection from MDBK cells. We show that treatment with long-alkyl-chain deoxynojirimycin derivatives, which are inhibitors of the endoplasmic reticulum (ER)-resident alpha-glucosidases, can greatly reduce the amount of secreted enveloped viral RNA. Long-alkyl-chain deoxygalactonojirimycin derivatives, which do not inhibit ER alpha-glucosidases, were less potent but still more effective in this system than IFN-alpha or ribavirin.

Active immunization against de novo hepatitis B virus infection in pediatric patients after liver transplantation

The shortage of donor organs occasionally mandates the use of hepatic allografts from anti-HBc (+) donors. HBIG and/or lamivudine are recommended for the prevention of de novo HBV infection in naive patients, but there are attendant problems, such as mutant strain emergence and high cost. Active immunization presents a better alternative than the use of HBIG or lamivudine, if it can be proven to be effective. Accordingly, we investigated the outcome of HBV vaccination in pediatric hepatic transplant recipients. Between July 1999 and October 2001, 19 pediatric recipients were administered HBV vaccinations after liver transplantation at Seoul National University Hospital. Nine patients received a graft from anti-HBc (+) donors and 10 from anti-HBc (-) donors. When steroid was withdrawn, recombinant HBV vaccine was administered. The median follow-up period after vaccination was 10.0 +/- 5.2 months. Seventeen of the 19 patients showed a positive response to vaccination. In 9 patients who received grafts from anti-HBc (+) donors, 2 patients showed no response, 4 patients low response (peak HBsAb titer <1,000 IU/L), and 3 patients high response (peak HBsAb titer >/=1,000 IU/L). De novo HBV infection developed in 1 of 2 patients who showed no response to vaccination. In 10 patients who received grafts from anti-HBc (-) donors, 5 showed a low response and 5 a high response. In conclusion, HBV vaccination in pediatric patients after liver transplantation appeared to exhibit some effectiveness at protecting young children that received a graft from anti-HBc (+) donors from de novo HBV infection.

Synergistic antiviral activity of human interferon combinations in the hepatitis C virus replicon system

The use of type I interferon (IFN), in combination with ribvirin, to treat chronic hepatitis C virus (HCV) infection has many drawbacks that prevent widespread application, ultimately leading to a significant unmet clinical need. Potential improvements in IFN therapy through targeted delivery, molecular alteration, and combination with other agents are ongoing in an attempt to decrease adverse effects and increase efficacy. In this report, the HCV replicon cell culture system was used to assess potential synergistic antiviral effects of multiple IFN species when administered in combination. Quantitative analysis of HCV replicon RNA by TaqMan (PE Applied Biosystems, Foster City, CA) and qualitative analysis of HCV protein expression were used to measure the antiviral efficacy of individual and combination IFN treatments, and synergistic responses of IFN combinations were determined through statistical analysis of the TaqMan results. We found that when administered simultaneously, type I/II IFN combinations (IFN-alpha2b + IFN-gamma or IFN-beta + IFN-gamma) resulted in dramatic antiviral synergy, whereas a type I/I combination (IFN-alpha2b + IFN-beta) demonstrated a slightly antagonistic profile. The synergistic effect is likely due to differential cell surface receptors and signaling pathways employed by types I and II IFNs. Conversely, all type I IFN species bind the same receptor and signal through similar pathways, possibly accounting for the nearly additive response observed. In support of this hypothesis, IFN treatment resulted in differential induction of Stat1 phosphorylation at Tyr 701. In conclusion, simultaneous type I/II IFN combination treatment may allow an overall decreased effective IFN dose, which may reduce the side effect profiles that hinder current therapy.

Inhibition of hepatitis B virus replication by drug-induced depletion of nucleocapsids

Chronic hepatitis B virus (HBV) infection is a major cause of liver disease. Only interferon-alpha and the nucleosidic inhibitors of the viral polymerase, 3TC and adefovir, are approved for therapy. However, these therapies are limited by the side effects of interferon and the substantial resistance of the virus to nucleosidic inhibitors. Potent new antiviral compounds suitable for monotherapy or combination therapy are highly desired. We describe non-nucleosidic inhibitors of HBV nucleocapsid maturation that possess in vitro and in vivo antiviral activity. These inhibitors have potential for future therapeutic regimens to combat chronic HBV infection.

Lamivudine Therapy for Japanese Patients with Cirrhosis B

OBJECTIVE

The aim of this study was to investigate the emergence of YMDD mutants in patients with chronic hepatitis B during lamivudine therapy and to compare the emergence patterns of YMDD mutants in cirrhotic and noncirrhotic patients.

METHODS

Eighteen cirrhotic and 37 noncirrhotic patients with chronic hepatitis B were studied. The emergence of YMDD mutants was determined before, as well as at 1, 3, 6, 9 and 12 months after treatment using a highly sensitive method based on polymerase chain reaction.

RESULTS

Although YMDD mutants were elicited early, the emergence of YMDD mutants was not always associated with breakthrough hepatitis. YMDD mutants appeared in cirrhotic and noncirrhotic patients: in 22 and 8% at 1 month, 13 and 21% at 3 months, 46 and 19% at 6 months, 30 and 19% at 9 months, and 83 and 27% at 12 months, respectively.

CONCLUSION

YMDD mutants emerge more frequently in cirrhotic than noncirrhotic patients during the early period on lamivudine treatment. The highly sensitive method may be useful for monitoring the development of YMDD mutants in patients with chronic hepatitis B during lamivudine therapy.

Detection of YMDD mutant using a novel sensitive method in chronic liver disease type B patients before and during lamivudine treatment

BACKGROUND/AIMS

The emergence of lamivudine-resistant hepatitis B virus (HBV) was reported in patients with prolonged lamivudine administration. There was no report of the existence of tyrosine-methionine-aspartate-aspartate (YMDD) mutant in non-lamivudine treated chronic hepatitis B patients. In the present study, we developed a sensitive assay and applied it to the detection of YMDD mutant.

METHODS

We developed peptide nucleic acid (PNA) mediated polymerase chain reaction clamping for detecting mutations in a YMDD motif of the hepatitis B virus DNA polymerase gene. We studied YMDD mutants in a patient with HBV DNA breakthrough longitudinally and in non-lamivudine treated patients (36 patients).

RESULTS

We could detect as little as 0.01-0.001% of mutant viruses coexisting in 10(5)-10(9) copies of wild-type viruses using this assay. YMDD mutant was detected 7 months before clinical breakthrough, which was 6 months earlier than using the conventional restriction fragment length polymorphism assay. YMDD mutants were also detected in four of 18 anti-HBe antibody positive untreated chronic hepatitis type B: YMDD+tyrosine-valine-aspartate-aspartate (YVDD) in two patients and YMDD+tyrosine-isoleucine-aspartate-aspartate (YIDD) in two patients, however, none in HBe antigen positive patients.

CONCLUSIONS

We developed a highly sensitive assay for detecting YMDD mutants. This is an effective procedure for monitoring patients during or before lamivudine treatment and can provide more insights into the therapeutic strategies for chronic hepatitis B patients.

Half-life of the duck hepatitis B virus covalently closed circular DNA pool in vivo following inhibition of viral replication

Covalently closed circular DNA (cccDNA) is a crucial intermediate in the replication of hepadnaviruses. We inhibited the replication of duck hepatitis B virus in congenitally infected ducks with a combination of lamivudine and a dideoxyguanosine prodrug. Inhibition of viral replication should prevent renewal of the cccDNA pool, and its decay was measured in liver biopsy samples collected over a 5-month period. In three ducks, the cccDNA pools declined exponentially, with half-lives ranging from 35 to 57 days. In two others, the pools declined exponentially for about 70 days but then stabilized at about 6 copies/diploid genome. The selection of drug-resistant virus mutants is an unlikely explanation for this unexpected stabilization of cccDNA levels. Liver sections stained for the cell division marker PCNA showed that animals in which cccDNA loss was continuous had significantly greater numbers of PCNA-positive nuclei than did those animals in which cccDNA levels had plateaued.