The complete nucleotide sequences of the cloned hepatitis B virus DNA; subtype adr and adw

Combined viral quasispecies diversity and hepatitis B core-related antigen predict off-nucleos(t)ide analog durability in HBeAg-negative patients

BACKGROUND

Viral quasispecies dynamics between pre- and post-nucleos(t)ide analog (NA) therapy remains unclear.

AIM

This study aimed to investigate the HBV quasispecies evolution and its relationship with durability of off-therapy responses in HBeAg-negative chronic hepatitis B (CHB) patients who stopped NA therapy.

METHODS

Fifty-four HBeAg-negative CHB patients who stopped NAs, including 19 virological controllers (VC) who maintained serum HBV DNA < 2000 IU/mL beyond 1-year off-therapy, and 35 virological relapsers (VR) experiencing virological relapse within 1-year off-therapy were recruited. Viral quasispecies was analyzed by deep sequencing. Hepatitis B core-related antigen (HBcrAg) and HBsAg were also measured.

RESULTS

VC had significantly higher baseline viral quasispecies diversity of the precore/core gene, measured by nucleotide diversity, than VR. Low baseline viral nucleotide diversity (< 0.01) and high HBcrAg (≧ 2.0 KU/mL), but not HBsAg, at end of treatment (EOT) were significantly associated with higher risk of 1-year virological relapse (hazard ratio [HR] 6.09 and 3.31, respectively). Combination of low baseline viral nucleotide diversity and high HBcrAg at EOT could identify patients at high risk (HR 15.82). Further analysis of the evolution of HBV whole genome showed that HBV nucleotide diversity negatively correlated with serum HBV DNA levels. Notably, the viral quasispecies diversity between pre- and post-NA treatment remained relatively unchanged.

CONCLUSION

Higher baseline HBV quasispecies diversity associates with more durable off-therapy viral suppression in HBeAg-negative CHB patients. Combination of baseline viral nucleotide diversity and HBcrAg at EOT can identify patients at high risk for virological relapse after stopping NAs.

The Regulation of HBV Transcription and Replication

Hepatitis B virus (HBV) is a major human pathogen lacking a reliable curative therapy. Current therapeutics target the viral reverse transcriptase/DNA polymerase to inhibit viral replication but generally fail to resolve chronic HBV infections. Due to the limited coding potential of the HBV genome, alternative approaches for the treatment of chronic infections are desperately needed. An alternative approach to the development of antiviral therapeutics is to target cellular gene products that are critical to the viral life cycle. As transcription of the viral genome is an essential step in the viral life cycle, the selective inhibition of viral RNA synthesis is a possible approach for the development of additional therapeutic modalities that might be used in combination with currently available therapies. To address this possibility, a molecular understanding of the relationship between viral transcription and replication is required. The first step is to identify the transcription factors that are the most critical in controlling the levels of HBV RNA synthesis and to determine their in vivo role in viral biosynthesis. Mapping studies in cell culture utilizing reporter gene constructs permitted the identification of both ubiquitous and liver-enriched transcription factors capable of modulating transcription from the four HBV promoters. However, it was challenging to determine their relative importance for viral biosynthesis in the available human hepatoma replication systems. This technical limitation was addressed, in part, by the development of non-hepatoma HBV replication systems where viral biosynthesis was dependent on complementation with exogenously expressed transcription factors. These systems revealed the importance of specific nuclear receptors and hepatocyte nuclear factor 3 (HNF3)/forkhead box A (FoxA) transcription factors for HBV biosynthesis. Furthermore, using the HBV transgenic mouse model of chronic viral infection, the importance of various nuclear receptors and FoxA isoforms could be established in vivo. The availability of this combination of systems now permits a rational approach toward the development of selective host transcription factor inhibitors. This might permit the development of a new class of therapeutics to aid in the treatment and resolution of chronic HBV infections, which currently affects approximately 1 in 30 individuals worldwide and kills up to a million people annually.

Insights From Deep Sequencing of the HBV Genome-Unique, Tiny, and Misunderstood

Hepatitis B virus (HBV) is a unique, tiny, partially double-stranded, reverse-transcribing DNA virus with proteins encoded by multiple overlapping reading frames. The substitution rate is surprisingly high for a DNA virus, but lower than that of other reverse transcribing organisms. More than 260 million people worldwide have chronic HBV infection, which causes 0.8 million deaths a year. Because of the high burden of disease, international health agencies have set the goal of eliminating HBV infection by 2030. Nonetheless, the intriguing HBV genome has not been well characterized. We summarize data on the HBV genome structure and replication cycle, explain and quantify diversity within and among infected individuals, and discuss advances that can be offered by application of next-generation sequencing technology. In-depth HBV genome analyses could increase our understanding of disease pathogenesis and allow us to better predict patient outcomes, optimize treatment, and develop new therapeutics.

14-3-3ζ binds to hepatitis B virus protein X and maintains its protein stability in hepatocellular carcinoma cells

14‐3‐3ζ, a phosphopeptide‐binding molecule, is reportedly overexpressed in the cancerous tissues of patients with hepatocellular carcinoma (HCC). Hepatitis B virus (HBV) protein X (HBx) draws intensive attention in HBV‐related HCC because it not only regulates HBV replication, but also promotes carcinogenesis by interacting with various tumor or antitumor molecules. This study is performed to investigate whether and how 14‐3‐3ζ interacts with HBx. The coimmunoprecipitation (Co‐IP) results showed that 14‐3‐3ζ bond to HBx in HBV‐infected Hep3B HCC cells and CSQT‐2 portal vein tumor thrombosis (PVTT) cells. By performing Co‐IP assay in HBV‐free Huh7 cells expressing wild‐type HBx, mutant HBx‐S31A, or HBx‐S31D (serine³¹ was mutated into alanine³¹ or aspartic acid³¹), we found that the phosphorylated serine³¹ with its near amino acid residues constituted a RPLphosphoS³¹GP (R, arginine; P, proline; L, leucine; S, serine; G, glycine) motif in HBx for 14‐3‐3ζ docking. This 14‐3‐3ζ‐HBx interaction was partly impaired when Akt signaling transduction was blocked by LY294002. Furthermore, 14‐3‐3ζ silencing augmented HBx ubiquitination and decreased its expression in cancer cells and xenograft tumor. The migratory and invasive abilities of CSQT‐2 cells were inhibited upon 14‐3‐3ζ silencing, whereas partly restored by HBx overexpression. Additionally, 14‐3‐3ζ positively correlated with HBx to be overexpressed in the primary HCC tissues (r = 0.344) and metastatic PVTT (r = 0.348). In summary, findings of this study reveal a novel 14‐3‐3ζ‐HBx interaction in HCC cells and suggest 14‐3‐3ζ as a candidate target for treating HBV‐related HCC.

HBx gene transfection affects the cycle of primary renal tubular epithelial cells through regulating cyclin expression

Hepatitis B virus X protein (HBx) has been previously demonstrated to be associated with the regulation of cell proliferation; however, the exact mechanisms underlying this effect remain unclear. The present study aimed to investigate the regulatory mechanism of HBx on the cycle progression of primary renal tubular epithelial cells. Primary renal tubular epithelial cells of Sprague Dawley (SD) rats were separated and cultured. The morphology of cultured cells was characterized by immunohistochemical analysis and the results demonstrated that primary renal tubular epithelial cells with the expected morphology and distribution were successfully separated and cultured from SD rats. HBx gene pcDNA3.1/myc vector and empty vector were constructed and transfected into cells as HBx and empty groups, respectively. Following transfection, the mRNA and protein levels of HBx, cyclin A, cyclin D1 and cyclin E in cells were determined by reverse transcription‑quantitative polymerase chain reaction and western blot analysis, respectively. The results demonstrated that following HBx gene transfection, the mRNA and protein levels of HBx, cyclin A, cyclin D1 and cyclin E in cells were significantly upregulated, compared with the empty control group (P<0.05). Furthermore, cell apoptosis and the cell cycle were evaluated by Annexin V‑fluorescein isothiocyanate/propidium iodide staining and flow cytometry. HBx gene transfection significantly inhibited the cell apoptosis (P<0.05), promoted cell cycle progression from the G1 to S phase and arrested the cell cycle in the S phase. Therefore, the results of the present study indicated that HBx gene transfection may regulate the apoptosis and cell cycle of primary renal tubular epithelial cells by affecting the expression of cyclins. The results of the present study may improve the understanding of pathogenesis associated with HBV‑associated glomerulonephritis, and may also provide insight and theoretical support for the future design and development of drugs for the treatment of hepatitis B virus.

The CRISPR/Cas9 System Facilitates Clearance of the Intrahepatic HBV Templates In Vivo

Persistence of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) under current antiviral therapy is a major barrier to eradication of chronic hepatitis B (CHB). Curing CHB will require novel strategies for specific disruption of cccDNA. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system is a newly developed tool for site-specific cleavage of DNA targets directed by a synthetic guide RNA (gRNA) base-paired to the target DNA sequence. To examine whether this system can cleave HBV genomes, we designed eight gRNAs against HBV of genotype A. With the HBV-specific gRNAs, the CRISPR/Cas9 system significantly reduced the production of HBV core and surface proteins in Huh-7 cells transfected with an HBV-expression vector. Among eight screened gRNAs, two effective ones were identified. Interestingly, one gRNA targeting the conserved HBV sequence acted against different genotypes. Using a hydrodynamics-HBV persistence mouse model, we further demonstrated that this system could cleave the intrahepatic HBV genome-containing plasmid and facilitate its clearance in vivo, resulting in reduction of serum surface antigen levels. These data suggest that the CRISPR/Cas9 system could disrupt the HBV-expressing templates both in vitro and in vivo, indicating its potential in eradicating persistent HBV infection.

The CRISPR/Cas9 System Facilitates Clearance of the Intrahepatic HBV Templates In Vivo

Persistence of hepatitis B virus (HBV) covalently closed circular DNA (cccDNA) under current antiviral therapy is a major barrier to eradication of chronic hepatitis B (CHB). Curing CHB will require novel strategies for specific disruption of cccDNA. The clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 system is a newly developed tool for site-specific cleavage of DNA targets directed by a synthetic guide RNA (gRNA) base-paired to the target DNA sequence. To examine whether this system can cleave HBV genomes, we designed eight gRNAs against HBV of genotype A. With the HBV-specific gRNAs, the CRISPR/Cas9 system significantly reduced the production of HBV core and surface proteins in Huh-7 cells transfected with an HBV-expression vector. Among eight screened gRNAs, two effective ones were identified. Interestingly, one gRNA targeting the conserved HBV sequence acted against different genotypes. Using a hydrodynamics-HBV persistence mouse model, we further demonstrated that this system could cleave the intrahepatic HBV genome-containing plasmid and facilitate its clearance in vivo, resulting in reduction of serum surface antigen levels. These data suggest that the CRISPR/Cas9 system could disrupt the HBV-expressing templates both in vitro and in vivo, indicating its potential in eradicating persistent HBV infection.

Adefovir and Lamivudine Combination Therapy in Patients with Entecavir-Resistant Chronic Hepatitis B: Antiviral Responses and Evolution of Mutations

<b><i>Objective:</i></b> This study was designed to prospectively evaluate the antiviral responses and evolution of resistance mutations during adefovir (ADV) plus lamivudine (LMV) therapy in patients with entecavir (ETV)-resistant hepatitis B virus (HBV) infection. <b><i>Methods:</i></b> Twenty chronic hepatitis B (CHB) patients who had been receiving ETV for more than 6 months and developed virologic breakthrough due to ETV resistance were consecutively enrolled. <b><i>Results:</i></b> Patients received ADV plus LMV therapy for 12 months. The baseline mean serum HBV DNA level was 5.59 ± 1.28 log₁₀ IU/ml. The rtT184L/I/A/F (50%), rtS202G (25%) and mixed ETV-resistant mutations (25%) were detected at enrollment. The mean reduction in serum HBV DNA levels from baseline to 12 months was -2.3 ± 1.06 log₁₀ IU/ml (p<i> <</i> 0.001). Seventeen patients were followed up for the full 12 months, and complete virologic response (HBV DNA <20 IU/ml) was observed in 4 patients (23.5%). Among the remaining 13 patients who still had detectable HBV DNA, 7 patients showed disappearance of ETV-resistant mutations or reduction of the proportion of ETV-resistant mutants. An ADV- and LMV-resistant mutant (rtA181T) emerged in 2 patients (11.7%). <b><i>Conclusions:</i></b> ADV plus LMV combination therapy suppresses ETV-resistant mutants in the viral population and significantly reduces serum HBV DNA levels in ETV-resistant CHB patients.

Adding adefovir vs. switching to entecavir for lamivudine-resistant chronic hepatitis B (ACE study): a 2-year follow-up randomized controlled trial

BACKGROUND

Management of lamivudine-resistant chronic hepatitis B (CHB) remains challenging, as inappropriate choice of treatment may cause multidrug resistance. Until now, randomized trials directly comparing adding adefovir and switching to entecavir monotherapy have not been reported.

AIMS

This multicentre prospective randomized study was designed to compare the efficacy of these two strategies.

METHODS

Two hundred and nineteen lamivudine-resistant CHB patients were randomized to either adefovir-lamivudine combination group or entecavir monotherapy group (n = 110 vs. 109), and followed up for 24 months.

RESULTS

One hundred and eighty patients completed this study. At month 24, virological response rate [hepatitis B virus (HBV) DNA <60 IU/ml] was higher in the adefovir-lamivudine combination group compared with entecavir group (56.7% vs. 40%, P = 0.025), although biochemical and serological response rates were not significantly different. Genotypic resistance (9.2% vs. 24.6%, P = 0.005) and combined viral breakthrough (2.0% vs. 17.6%, P < 0.001) were more frequent in the entecavir group. However, by subgroup analysis, virological response rates were not significantly different between the two therapies in HBeAg-positive patients (44.9% vs. 35.7%, P = 0.268) or in patients with high baseline HBV DNA (≥7 log IU/ml) (40.7% vs. 31.3%, P = 0.320) at month 24.

CONCLUSION

This study showed that adefovir-lamivudine combination provides significantly higher antiviral efficacy and the lower resistance rate compared with the entecavir monotherapy in the management of lamivudine-resistant CHB. However, it had limited efficacy in HBeAg-positive patients or in patients with high baseline HBV DNA.

HBVdb: a knowledge database for Hepatitis B Virus

We have developed a specialized database, HBVdb (http://hbvdb.ibcp.fr), allowing the researchers to investigate the genetic variability of Hepatitis B Virus (HBV) and viral resistance to treatment. HBV is a major health problem worldwide with more than 350 million individuals being chronically infected. HBV is an enveloped DNA virus that replicates by reverse transcription of an RNA intermediate. HBV genome is optimized, being circular and encoding four overlapping reading frames. Indeed, each nucleotide of the genome takes part in the coding of at least one protein. However, HBV shows some genome variability leading to at least eight different genotypes and recombinant forms. The main drugs used to treat infected patients are nucleos(t)ides analogs (reverse transcriptase inhibitors). Unfortunately, HBV mutants resistant to these drugs may be selected and be responsible for treatment failure. HBVdb contains a collection of computer-annotated sequences based on manually annotated reference genomes. The database can be accessed through a web interface that allows static and dynamic queries and offers integrated generic sequence analysis tools and specialized analysis tools (e.g. annotation, genotyping, drug resistance profiling).

Structure and expression of integrated hepatitis B virus genes in an HBs antigen producing human cell line (huGK-14)

A human continuous cell line (huGK-14) within a lineage of passaged cultures was investigated in the mode of integration and expression of hepatitis B virus (HBV) genes. HBV DNA was integrated in eight different sites of the cellular DNA, in each of which HBV genome was rearranged, fragmented, and/or partly deleted. Complete HBV genome that may lead to production of infectious virus particles was not detected in the cells nor in the culture medium. Clones of cDNA containing a complete coding frame for small HBs antigen protein (type adr) were obtained from mRNA of the cells. The cells were stable over the period of six months of cultivation and more than 60 population doublings in the mode of HBV integration and HBs mRNA expression.These results provide substantial evidence for the absence of an ability for the integrated DNA to create an infectious product in the cell; for the stable production of HBs mRNA from the cells, and suggest the usefulness of this cell line as a substrate for HBV vaccine production.

Comparison of multiplex restriction fragment mass polymorphism and sequencing analyses for detecting entecavir resistance in chronic hepatitis B

BACKGROUND

Drug resistance is a major limitation to the long-term efficacy of controlling chronic hepatitis B (CHB). There is a growing need to analyse multiple mutations associated with drug resistance because sequential or combinational use of antivirals is increasingly being used in treatment. In this study, we introduced a multiplex restriction fragment mass polymorphism (RFMP) assay for detecting mutations conferring entecavir and lamivudine resistance, and compared its performance with direct or clonal sequencing assays.

METHODS

Multiplex PCR was performed with mixed primers designed to interrogate rt184, rt202, rt204 and rt250. The PCR products were digested with restriction enzymes and the resulting fragments were analysed by mass spectrometry. A total of 251 serum samples, taken serially from 45 patients who received entecavir treatment after confirmed diagnosis of lamivudine resistance and inadequate adefovir dipivoxil response, were analysed by the multiplex RFMP assay.

RESULTS

The multiplex RFMP assay correctly identified known viral sequences with sufficient analytical sensitivity to detect as few as 100 IU/ml of HBV and with superior ability to determine haplotypes composed of neighbouring variations. Complex mutational patterns and relative abundances determined by multiplex RFMP assay were in good concordance with results obtained by direct or clonal sequencing analyses. Defined mixtures were successfully and consistently identified at 2% relative concentration of mutant versus wild-type virus by the assay.

CONCLUSIONS

The multiplex RFMP assay is an accurate and sensitive means to detect entecavir and lamivudine resistance mutations, simultaneously. The method is expected to enable early and efficient diagnosis of multiple drug resistance mutations for optimal management of CHB.

Neutralizing anti-gH antibody of Varicella-zoster virus modulates distribution of gH and induces gene regulation, mimicking latency

The anti-glycoprotein H (gH) monoclonal antibody (anti-gH-MAb) that neutralizes varicella-zoster virus (VZV) inhibited cell-to-cell infection, resulting in a single infected cell without apoptosis or necrosis, and the number of infectious cells in cultures treated with anti-gH-MAb declined to undetectable levels in 7 to 10 days. Anti-gH-MAb modulated the wide cytoplasmic distribution of gH colocalized with glycoprotein E (gE) to the cytoplasmic compartment with endoplasmic reticulum (ER) and Golgi markers near the nucleus, while gE retained its cytoplasmic distribution. Thus, the disintegrated distribution of gH and gE caused the loss of cellular infectivity. After 4 weeks of treatment with anti-gH-MAb, no infectious virus was recovered, even after cultivation without anti-gH-MAb for another 8 weeks or various other treatments. Cells were infected with Oka varicella vaccine expressing hepatitis B surface antigen (ROka) and treated with anti-gH-MAb for 4 weeks, and ROka was recovered from the quiescently infected cells by superinfection with the parent Oka vaccine. Among the genes 21, 29, 62, 63, and 66, transcripts of gene 63 were the most frequently detected, and products from the genes 63 and 62, but not gE, were detected mainly in the cytoplasm of quiescently infected cells, in contrast to their nuclear localization in lytically infected cells. The patterns of transcripts and products from the quiescently infected cells were similar to those of latent VZV in human ganglia. Thus, anti-gH-MAb treatment resulted in the antigenic modulation and dormancy of infectivity of VZV. Antigenic modulation by anti-gH-MAb illuminates a new aspect in pathogenesis in VZV infection and the gene regulation of VZV during latency in human ganglia.

Efficacy of adefovir add-on lamivudine rescue therapy compared with switching to entecavir monotherapy in patients with lamivudine-resistant chronic hepatitis B

No study has reported on the comparative effect of adefovir (ADV) add-on lamivudine (LAM) versus switching to entecavir (ETV) in LAM-resistant patients with chronic hepatitis B. From October 2007 to September 2008, 92 consecutive LAM-resistant patients were enrolled (47 LAM+ADV and 45 ETV 1 mg). All patients were followed for at least 12 months. The parameters assessed included normalization of ALT, HBeAg seroconversion, undetectable HBV DNA, reduction of HBV DNA, and predictors of virologic response. In the LAM+ADV and ETV groups, the baseline DNA levels were 7.61 (5.19-9.49) and 7.10 (5.43-9.74)log(10)copies/ml, respectively. At month 12, a virologic response occurred in 18/47 (38.3%) and 11/45 (24.4%; P=0.182) patients; ALT normalization, in 39/41 (95.1%) and 36/40 (90.0%; P=0.432); HBeAg seroconversion, in 5.1% and 2.4% (P=0.606); and virologic breakthrough, in 2.1% and 11.1% (P=0.107), respectively. The mean reduction from the baseline HBV DNA level was greater in the LAM+ADV group at month 12 (3.80 ± 1.12 vs. 2.7 ± 1.32 log(10)copies/ml; P<0.001). In the multivariate analysis, the independent parameters related to a virologic response at month 12 were baseline ALT (OR=1.003, 95% CI=1.000-1.006, P=0.026) and baseline HBV DNA (OR=0.495, 95% CI=0.298-0.823, P=0.007). Compared with switching to ETV monotherapy, ADV add-on LAM therapy was more effective at reducing the viral load in patients with LAM resistance, and the baseline HBV DNA and ALT levels were independent predictors of the virologic response. However, ADV add-on therapy had limitations in patients with a higher baseline HBV DNA in LAM rescue therapy.

Lamivudine-to-entecavir switching treatment in type B chronic hepatitis patients without evidence of lamivudine resistance

PURPOSE

A considerable number of chronic hepatitis B (CH-B) patients remain under continuous lamivudine treatment, although switching treatment to entecavir could be beneficial. We investigated the antiviral efficacy of switching treatment to entecavir in CH-B patients without apparent evidence of lamivudine resistance during the preceding lamivudine treatment.

METHODS

Forty-four CH-B patients, who underwent lamivudine treatment for more than 6 months and showed no evidence of lamivudine resistance, switched to entecavir. Serial changes in hepatitis B virus (HBV) DNA were correlated with the patients' baseline HBV DNA at the commencement of entecavir administration. The entecavir-resistant substitution was examined by PCR-direct sequencing. The median follow-up period of entecavir treatment was 20 (10-23) months.

RESULTS

All 31 patients with baseline HBV DNA <2.6 logcopies/ml maintained HBV DNA-negative status during entecavir treatment. Of seven patients having HBV DNA of 2.6-<4.0 logcopies/ml, all achieved undetectable HBV DNA at the end of follow-up. As for six patients having HBV DNA >or=4.0 logcopies/ml, three patients achieved undetectable HBV DNA, whereas virological breakthrough was observed in one patient at month 15. An entecavir-resistant virus having rtM204V, rtL180M and rtS202G substitutions was detected in this patient.

CONCLUSIONS

The lamivudine-to-entecavir switching treatment may be generally recommendable in CH-B patients without evidence of lamivudine resistance during the preceding lamivudine treatment. However, great care should be taken with respect to the emergence of entecavir-resistance, especially in patients who do not respond well to the preceding lamivudine treatment.

Rescue Monotherapy in Lamivudine-Resistant Hepatitis B e Antigen-Positive Chronic Hepatitis B: Adefovir versus Entecavir

Background

The efficacy of adefovir dipivoxil (ADV) or entecavir (ETV) rescue monotherapy has not been directly compared in hepatitis B e antigen (HBeAg)- positive patients with lamivudine (3TC)-resistant chronic hepatitis B (CHB). We compared the efficacy of ADV and ETV rescue monotherapy in HBeAg-positive patients with confirmed genotypic 3TC resistance.

Methods

A total of 160 HBeAg-positive patients with confirmed 3TC resistance underwent switch therapy (91 ADV and 59 ETV). Parameters assessed included alanine aminotransferase (ALT) normalization, HBeAg serocon-version, undetectable serum hepatitis B virus (HBV) DNA by PCR (lower detection limit <300 copies/ml), virological breakthrough and initial virological response (IVR) at 3 (IVR-3) and 6 (IVR-6) months.

Results

Following 52 weeks of treatment in the ADV and ETV groups, serum HBV DNA became undetectable in 25 (27.5%) and 21 (35.6%; P=0.292) patients, ALT normalization occurred in 67/78 (85.9%) and 43/47 (91.5%; P=0.351), HBeAg seroconversion in 4 (4.4%) and 1 (1.7%; P=1.000), IVR-3 in 19 (20.9%) and 18 (30.5%), IVR-6 in 40 (44.0%) and 25 (42.4%) and virological breakthrough in 2 (2.2%) and 1 (1.7%; P=1.000) patients, respectively.

Conclusions

ADV and ETV revealed comparable efficacy after 52 weeks of treatment in HBeAg-positive patients with 3TC resistance. Undetectable HBV DNA in serum following 52 weeks of treatment was predictable with IVR-3 and IVR-6 in both groups.

Association of lamivudine-resistant mutational patterns with the antiviral effect of adefovir in patients with chronic hepatitis B

Adefovir has a potent antiviral activity as a rescue treatment against lamivudine-resistant strains. The aim of this study was to assess the patterns of lamivudine-resistant mutations and their influence on the virologic response to adefovir rescue therapy in patients with lamivudine-resistant chronic hepatitis B. Sixty-seven patients with lamivudine-resistant chronic hepatitis B were treated with adefovir monotherapy. Baseline blood samples were analyzed for lamivudine-resistant mutations via restriction fragment mass polymorphism. Virologic responses, ALT normalization and loss of HBeAg were assessed. Serum HBV DNA levels were measured using real-time PCR at baseline and 24 weeks of adefovir therapy. Of the 67 patients with chronic hepatitis B, 65 patients (97%) had lamivudine-resistant mutations in the YMDD motif [27 (41%) rtM204I, 22 (34%) rtM204V, and 16 (25%) rtM204I/V]. In addition to the YMDD mutations, the rtL180M, rtL80I, and rtV173L mutations were also present in 78%, 43%, and 11% of patients, respectively. The rtM204V mutation always accompanied rtL180M, and rtL80I was always observed in conjunction with rtM204I. Decrease in mean serum HBV did not differ between patients carrying the rtM204I versus rtM204V mutant at week 24 (-3.3 vs. -3.3 log(10) copies/ml, respectively; P = 0.303). The presence of the rtL180M, rtL80I, and rtV173L did not significantly affect viral load reduction during adefovir administration. These results demonstrate that the rtL80I mutant is co-selected with rtM204I as a compensatory mutation in the same manner as rtL180M with rtM204V, and that adefovir shows similar antiviral efficacy against all of the evaluated patterns of lamivudine-resistant HBV mutations.

Human oncogenic viruses: hepatitis B and hepatitis C viruses and their role in hepatocarcinogenesis

Chronic infections caused by hepatitis B virus (HBV) and/or hepatitis C virus (HCV) are the main risk factors for the development of hepatocellular carcinoma (HCC) in humans. Both viruses cause a wide spectrum of clinical manifestations ranging from healthy carrier state to acute and chronic hepatitis, liver cirrhosis, and HCC. HBV and HCV belong to different viral families (Hepadnoviridae and Flaviviridae, respectively); they are characterized by different genetic structures. Clinical manifestations of these viral infections result from the interaction between these viruses and host hepatocytes (i.e. between viral and cell genomes). Proteins encoded by both viruses play an important role in processes responsible for immortalization and transformation of these cells. Chronic inflammation determined by host immune response to the viral infection, hepatocyte death and their compensatory proliferation, as well as modulation of expression of some regulatory proteins of the cell (growth factors, cytokines, etc.) are the processes that play the major role in liver cancer induced by HBV and HCV.

Efficient amplification with NASBA of hepatitis B virus, herpes simplex virus and methicillin resistant Staphylococcus aureus DNA

A new mechanism is described for DNA amplification using nucleic acid sequence-based amplification (NASBA) including a restriction enzyme digestion and P1 primer binding directly upstream of the digestion. For hepatitis B virus (HBV), herpes simplex virus (HSV) and methicillin resistant Staphylococcus aureus (MRSA) DNA, which all show very poor amplification with normal NASBA, assay sensitivity was improved by a factor 100-1000 when restriction enzyme digestion was performed prior to amplification. For the quantitative HBV assay, in combination with the NucliSENS Extractor (bioMérieux, Boxtel, The Netherlands), a 95% target detection rate of 242 WHO IU/ml and 50% detection rate of 35 WHO IU/ml was achieved. The lowest detectable HBV concentration was 10 WHO IU/ml. HBV DNA could be quantified with an algorithm comparable to that used for RNA quantitation and by using a two step approach a dynamic range of 10(2)-10(9)WHO IU/ml (>6 log) was shown to be quantifiable. For the qualitative HSV assay, in combination with the NucliSENS miniMAG (bioMérieux, Boxtel, The Netherlands), the 95% detection rate was determined to be 84 and 138 copies/isolation for HSV 1 and HSV 2, respectively, which corresponds to approximately 10 copies per amplification for both targets. For MRSA, the limit of detection was <10 equivalent CFU per amplification.

Impact of hepatitis B virus (HBV) X gene integration in liver tissue on hepatocellular carcinoma development in serologically HBV-negative chronic hepatitis C patients

BACKGROUND/AIMS

We analyzed hepatitis B virus (HBV) X gene integration in hepatocytes of HBV-negative, chronic hepatitis C (CH-C) patients with mild fibrosis, and prospectively followed these patients for the development of hepatocellular carcinoma (HCC).

METHODS

The study included 39 HBV-negative CH-C patients with mild fibrosis. HBV-X integration was determined by Alu-PCR analysis of liver specimens obtained by fine-needle biopsy.

RESULTS

Integration of HBV-X gene sequence into liver genome occurred in 9 of the 39 patients. Six of the 39 patients developed HCC during the 12-year follow-up period. No significant difference was found in the incidence of HCC between patients with and without HBV-X integration. However, the two patients with HBV-X integration who developed HCC did not have cirrhosis at the time when HCC was diagnosed, whereas the four patients without HBV-X integration who developed HCC did have cirrhosis.

CONCLUSIONS

Our findings suggest that HBV-X integration detected at the mild fibrosis stage might not indicate a high risk for HCC. HBV-X integration may be associated with HCC development in the absence of cirrhosis. However, we did not find evidence that HBV-X integration directly plays a role in hepatocarcinogenesis in CH-C patients. Further studies will be needed to clarify this point.

Levels of hepatitis B virus (HBV) replication during the nonreplicative phase: HBV quantification by real-time PCR in Korea

The levels of HBV replication in the nonreplicative phase are not clear. We conducted this study to evaluate the levels of viral replication during the nonreplicative phase in chronic HBV-infected Korean patients using real-time PCR. A total of 125 patients were classified into three groups: inactive HBsAg carriers, inactive liver cirrhosis patients, and resolved chronic HBV-infected patients with loss of HBsAg. The real-time PCR detected HBV DNA in 112 cases (89.6%). The mean levels of HBV DNA were 3.84, 4.10, and 3.31 log copies/ml in the three groups, respectively (P <0.01). Ninety-five percent of inactive HBsAg carriers showed levels of HBV DNA lower than 6 x 10(4) copies/ml. In conclusion, we showed different levels of HBV DNA exactly in three groups during nonreplicative phases. We suggest that the cutoff level of HBV DNA in inactive HBsAg carriers should be readjusted to a lower level in future studies.

Antiviral efficacy of adefovir dipivoxil versus lamivudine in patients with chronic hepatitis B sequentially treated with lamivudine and adefovir due to lamivudine resistance

AIM: To compare the antiviral efficacy of adefovir (ADV) in lamivudine (LMV)-resistant patients with LMV treatment in nucleoside-naïve patients, using serum samples collected sequentially during the course of treatment progressing from LMV to ADV.

METHODS: Forty-four patients with chronic hepatitis B (CHB) were included. The patients were initially treated with LMV and then switched to ADV when LMV resistance developed. Antiviral efficacy was assessed by measuring the following: reduction in serum HBV DNA from baseline, HBV DNA negative conversion (defined as HBV DNA being undectable by the hybridization assay), and HBV DNA response (either HBV DNA level ≤ 10⁵ copies/mL or a ≥ 2 log₁₀ reduction from baseline HBV DNA level).

RESULTS: After two and six months of treatment, HBV DNA reduction was greater with LMV compared to ADV treatment (P = 0.021). HBV DNA negative conversion rates were 64% and 27% after one month of LMV and ADV treatment respectively (P = 0.001). Similarly, HBV DNA response rates were 74% and 51% after two months of LMV and ADV treatment respectively (P = 0.026).

The time taken to HBV DNA negative conversion and to HBV DNA response were both delayed in ADV treatment compared with LMV.

CONCLUSION: The antiviral efficacy of ADV in LMV-resistant patients is slower and less potent than that with LMV in nucleoside-naïve patients during the early course of treatment.

High level of genetic heterogeneity in S and P genes of genotype D hepatitis B virus

The genetic heterogeneity of hepatitis B virus (HBV) genotypes and subgenotypes was investigated by directly sequencing amplified PreS, S and P genes of HBV isolates obtained from the plasma of 99 subjects with chronic HBV infection. Genotype D showed the greatest intragenotypic and intrasubgenotypic divergence: in particular, the a determinant was mutated in 58.2% of the genotype D patients, two of whom showed prototypic vaccine-induced escape mutants at codon 145. Moreover, five sites under significant positive selection were found in the S protein of the D isolates: one in the a determinant and four in the highly hydrophobic C terminal. Our results suggest that careful surveillance of vaccine-induced escape mutants should be considered in populations with highly frequent genotype D infections, and raise questions concerning the possible relationship between the genetic heterogeneity, host immunity and pathogenicity of this HBV genotype.

Active immunization to prevent de novo hepatitis B virus infection in pediatric live donor liver recipients

This study aims to evaluate the efficacy of HBV vaccination as an alternative preventive measure against de novo HBV infection in pediatric living donor liver transplantation (LDLT). Sixty recipients were enrolled in this study. Thirty received grafts from anti-HBc(+) donors, and another 30 received grafts from anti-HBc(-) donors. HBV vaccine was given pretransplant to every candidate. Posttransplant, lamivudine was routinely given to recipients receiving anti-HBc(+) grafts for about 2 years. Forty-seven (78%) recipients achieved high levels of anti-HBs titer (>1000 IU/L). Two (3.3%) recipients developed de novo HBV infection where one received an anti-HBc(-) graft and another received an anti-HBc(+) graft. Both recipients were in the lower anti-HBs titer group (<1000 IU/L). The incidence of de novo HBV infection was significantly higher in the lower titer group (15.4% vs. 0%, p = 0.04). The median follow-up period was 51 months in recipients with anti-HBc(-) grafts and 57 months in those with anti-HBc(+) grafts. Active immunization is an effective method to prevent de novo HBV infection. It can result in high levels of anti-HBs titer (>1000 IU/L) which may prevent de novo HBV infection in pediatric patients with efficient primary vaccination undergoing LDLT.

Resistance to adefovir dipivoxil in lamivudine resistant chronic hepatitis B patients treated with adefovir dipivoxil

BACKGROUND

Adefovir dipivoxil (ADV) is a potent nucleotide analogue against both the wild-type and lamivudine (LMV) resistant hepatitis B virus (HBV). The cumulative incidence of ADV resistant mutations in the nucleoside/-tide treatment naive chronic hepatitis B patient (CHB) at weeks 48, 96, and 144 was 0, 0.8-3%, and approximately 5.9%, respectively.

AIMS

The aim of this study was to characterise the genotypic and phenotypic mutation profiles to ADV in 67 LMV resistant CHB patients who were treated with ADV.

METHODS

Serum HBV DNA was quantified by real time polymerase chain reaction. The ADV mutant was detected using matrix assisted laser desorption/ionisation time of flight mass spectrometry based genotyping assays, termed restriction fragment mass polymorphism (RFMP).

RESULTS

RFMP analysis revealed that a total of 11 amino acid substitutions developed in the rt domain of the HBV polymerase in nine patients. The cumulative incidence of genotypic ADV resistance at months 12 and 24 was 6.4% and 25.4%, respectively. The rtA181V, rtN236T, and rtA181T mutations were detected in five, four, and two of the 67 patients at treatment months 12-17, 3-19, and 7-20, respectively. Serial quantification of serum HBV DNA revealed that two patients with the rtA181V mutation, with or without the rtN236T mutation, and one patient with the rtA181T mutation displayed HBV DNA rebound.

CONCLUSION

Emergence of the ADV mutation in LMV resistant patients who are treated with ADV appeared to present earlier and more frequently than was reported in previous studies on nucleoside/-tide treatment naive patients.

Study on hepatitis B virus pre-S/S gene mutations of renal tissues in children with hepatitis B virus-associated membranous nephropathy

This study aims to clarify the prevalence and significance of the emergence of hepatitis B virus (HBV) pre-S/S mutations in children with hepatitis B virus-associated membranous nephropathy (HBVMN). Direct sequencing of polymerase chain reaction products of renal tissue samples that were obtained via percutaneous renal biopsy from seven children revealed the presence of HBV DNA. Seven adr subtypes were analyzed. Deletions in the HBV pre-S region were observed once per seven patients. The deletions were noted in both the pre-S1 (27 bp) and pre-S2 (60 bp) regions. Various point mutations in the HBV pre-S region were detected in all seven patients and proved to be more frequent in the pre-S1 region than in the S2 region. Point mutations in the HBV S region were detected in six patients. Among these mutations, the mutation in the "a" determinant region was noted in five patients. No deletion, however, was observed in the HBV S region. These observations suggested that deletions and point mutations in the HBV pre-S1 and pre-S2 regions and point mutations in the HBV S region, especially the "a" determinant region, are common frequent findings. These results also suggested that HBV pre-S/S region mutations may be involved in the pathogenesis in children with HBVMN.

Increased risk of adefovir resistance in patients with lamivudine-resistant chronic hepatitis B after 48 weeks of adefovir dipivoxil monotherapy

Although adefovir dipivoxil (ADV) has a unique profile of delayed and infrequent resistance in treatment-naïve chronic hepatitis B patients, the association of ADV resistance with previous lamivudine (LAM) resistance is not well understood. We compared the emergence of the ADV-resistant mutations rtA181V/T and rtN236T between LAM-resistant patients and treatment-naïve patients at 48 weeks of ADV monotherapy. Fifty-seven LAM-resistant patients and 38 treatment-naïve patients were treated with 10 mg/d ADV for more than 48 weeks. Both baseline and 48-week blood samples were analyzed for ADV-resistant mutations via restriction fragment mass polymorphism analysis. Antiviral responses were evaluated according to changes in serum HBV DNA (measured via real-time polymerase chain reaction) and alanine aminotransferase (ALT) levels and loss of hepatitis B e antigen (HBeAg). After 48 weeks, 10 (18%) of the 57 LAM-resistant patients were found to have developed ADV-resistant mutations, whereas none of the 38 treatment-naïve patients developed such mutations (P < .01). Among LAM-resistant patients, the reduction in serum HBV DNA levels was significantly lower in patients with ADV-resistant mutations than in those without such mutations (-1.04 vs. -2.63 log10 copies/mL) (P = .01). However, the rates of serum ALT normalization (60% vs. 55%) and HBeAg loss (14% vs. 21%) were not significantly different between the 2 groups (P > .05). In conclusion, the emergence of the rtA181V/T and rtN236T mutations was more common in LAM-resistant patients than in treatment-naïve patients after 48 weeks of ADV therapy and was associated with reduced antiviral efficacy to drug treatment.

Predominance of hepatitis B virus YMDD mutants is prognostic of viral DNA breakthrough

BACKGROUND & AIMS

Hepatitis B virus (HBV) tyrosine, methionine, aspartate, aspartate (YMDD) mutants with or without additional compensatory mutations occur in chronically infected patients during lamivudine therapy and may be associated with accompanying viral breakthrough. The aim of this study was to determine whether a predominance of YMDD mutants could be a prognostic marker for occurrence of viral DNA breakthrough.

METHODS

YMDD genotypes in 740 consecutive samples collected from 116 patients throughout lamivudine treatment were retrospectively analyzed using a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS)-based genotyping assay, termed restriction fragment mass polymorphism (RFMP). RFMP exploits differences in molecular masses between wild-type and variant bases of rtM204V/I following PCR amplification of HBV DNA with a lower limit of detection being 100 copies/mL.

RESULTS

The study demonstrated that YMDD mutants occur throughout the course of lamivudine therapy irrespective of occurrence of viral DNA breakthrough, indicating that a mere detection of YMDD mutants could not sufficiently predict the viral DNA breakthrough, although presence of YMDD mutants is associated with high incidence of viral DNA breakthrough (odds ratio, 7.8; P = .0012; relative risk = 8.7%), and a 5-fold predominance of YMDD mutant to wild-type virus was significantly associated with viral DNA breakthrough (odds ratio, 604.5; P < .0001; relative risk = 93.8%).

CONCLUSIONS

Close and periodical testing by RFMP assay should be useful to detect the predominance of YMDD mutants for monitoring drug resistance, enabling early intervention and prevention.

Large scaled analysis of hepatitis B virus (HBV) DNA integration in HBV related hepatocellular carcinomas

BACKGROUND AND AIMS

Hepatitis B virus (HBV) DNA integration into or close to cellular genes is frequently detected in HBV positive hepatocellular carcinomas (HCC). We have previously shown that viral integration can lead to aberrant target gene transcription. In this study, we attempted to investigate common pathways to hepatocarcinogenesis.

METHODS

By using a modified Alu-polymerase chain reaction approach, we analysed 50 HCCs along with 10 previously published cases.

RESULTS

Sixty eight cellular flanking sequences (seven repetitive or unidentified sequences, 42 cellular genes, and 19 sequences potentially coding for unknown proteins) were obtained. Fifteen cancer related genes and 25 cellular genes were identified. HBV integration recurrently targeted the human telomerase reverse transcriptase gene (three cases) and genes belonging to distinct pathways: calcium signalling related genes, 60s ribosomal protein encoding genes, and platelet derived growth factor and mixed lineage leukaemia encoding genes. Two tumour suppressor genes and five genes involved in the control of apoptosis were also found at the integration site. The viral insertion site was distributed over all chromosomes except 13, X, and Y.

CONCLUSIONS

In 61/68 (89.7%) cases, HBV DNA was integrated into cellular genes potentially providing cell growth advantage. Identification of recurrent viral integration sites into genes of the same family allows recognition of common cell signalling pathways activated in hepatocarcinogenesis.

Label-Free Electrochemical Hybridization Genosensor for the Detection of Hepatitis B Virus Genotype on the Development of Lamivudine Resistance

The resistance analysis related to the hepatitis B virus (HBV) genotyping and treatment procured key information for the study of infected patients. The aim of this study was to develop a novel assay for the voltammetric detection of DNA sequences related to the HBV genotype on the development of lamuvidine resistance by monitoring the oxidation signal of guanine. This new technique not only provides a rapid, cost-effective, simple analysis but also gives information concerning both genotyping and lamivudine resistance. Synthetic single-stranded oligonucleotides ("probe") including YMDD (HBV wild type) YVDD, or YIDD (mutations in the YMDD) variants have been immobilized onto pencil graphite electrodes with the adsorption at a controlled potential. The probes were hybridized with different concentrations of their complementary ("target") sequences such as synthetic complementary sequences, clonned PCR products, or real PCR samples. The formed synthetic hybrids on the electrode surface were evaluated by a differential pulse voltammetry technique using a label-free detection method. The oxidation signal of guanine was observed as a result of the specific hybridization between the probes and their synthetic targets and specific PCR products. The response of the hybridization of the probes with their single-base mismatch oligonucleotides at PGE was also detected. Control experiments using the noncomplementary oligonucleotides were performed to determine whether the DNA genosensor responds selectively. Numerous factors, affecting the probe immobilization, target hybridization, and nonspecific binding events, were optimized to maximize the sensitivity and reduce the assay time. Under the optimum conditions, 457 fmol/mL was found as the detection limit for target DNA. With the help of the appearance of the guanine signal, the new protocol is based on the electrochemical detection of HBV genotype for the development of lamuvidine resistance for the first time. Features of this protocol are discussed and optimized.

Non-responsiveness to hepatitis B surface antigen vaccines is not caused by defective antigen presentation or a lack of B7 co-stimulation

The mechanisms causing non-responsiveness to hepatitis B surface antigen (HBsAg) vaccines in man remain elusive. The increased incidence of non-responsiveness in subjects with HLA-DR3(+) or -DR7(+) haplotypes suggests that immune response mechanisms governed by genes of the MHC are involved. Homozygotes for these two haplotypes are found almost exclusively in the non-responder (NR) population. It is conceivable that antigen-presenting cells (APC) of NR are defective in the uptake of HBsAg and that they are unable to present this Ag adequately. Previously, we demonstrated that DR2(+), DR7(+) and DP4(+) NR were able to present HBsAg. In the present paper we demonstrate that six DR0301(+) NR, five of which are homozygous for this marker, were able to take up, process and present HBsAg to HBsAg-specific, DR0301-restricted T cell lines. Non-fractionated peripheral blood mononuclear cells (PBMC) from the DR0301(+) NR did not proliferate to HBsAg in vitro, whereas they proliferated vigorously upon stimulation with tetanus toxoid, thus ruling out the presence of a generalized immunodeficiency. We therefore conclude that HLA-DR0301(+) NR vaccinees are not deficient in their HBsAg-presentation. Because it was demonstrated that recently activated T cells can apparently bypass the requirement for B7, we may have overlooked the role of the B7-co-stimulation in our set-up that used HBsAg-specific T cell lines. Therefore we examined the expression of B7 co-stimulatory molecules on NR-APC. CD86 was normally present on these cells and was not down-regulated after culturing the PBMC in the presence of HBsAg. We conclude that CD86 expression on CD14(+) monocytes of DR0301- and DR07-homozygous poor responders is not deficient and cannot be the mechanism underlying the non-responsiveness of these subjects.

Difference in hTERT gene expressions between HbsAg-positive and HbsAg-negative hepatocellular carcinoma

To investigate the difference in expression of hTERT gene between HbsAg-positive human hepatocellular carcinoma (HCC) and HbsAg-negative HCC and to explore the relationship between HBV infection and hTERT gene expression in HCC. The expression of hTERT protein in 30 cases of HbsAg positive HCC and 17 cases of HbsAg negative HCC was detected by immunohistochemistry (SP method), and the expression of hTERT mRNA was analyzed by reverse transcription polymerase chain reaction (RT-PCR). t-test, Chi-squared test and cochran- armitage trend test were used to see whether there was an interrelation between HBsAg and hTERT gene in HCC. The expression of hTERT protein was mostly located in plasm and occasionally in the nucleus of liver cancer cells. The positive rate of hTERT protein and hTERT mRNA in HbsAg positive HCC- 93.33% (28/30) and 83.33% (25/30) respectively which were much higher than those in HbsAg negative HCC- 52.94% (9/17), 47.06% (8/17) (P<0.01) respectively. HbsAg is related to hTERT gene expression in human hepatocellular carcinoma. The hTERT gene activated by the efficacious ingredient of HBV may play an important role in hepatocellular transformation and carcinogenesis.

HBV core sequence: definition of genotype-specific variability and correlation with geographical origin

There are eight genotypes and nine subtypes of HBV. Small differences in geographical origin are associated with sequence changes in the surface gene. Here, we compared core gene sequences from different genotypes and geographical regions. Specific combinations of 24 amino acid substitutions at nine residues allowed allocation of a sequence to a subtype. Six of these nine residues were located in different T cell epitopes depending on HBV geographical area and/or genotype. Thirty-seven nucleotide changes were associated uniquely with specific genotypes and subtypes. Unique amino acid and nucleotide variants were found in a majority of sequences from specific countries as well as within subtype ayw2 and adr. Specific nucleotide motifs were defined for Korean, Indian, Chinese, Italian and Pacific region isolates. Finally, we observed amino acid motifs that were common to either South-east Asian or Western populations, irrespective of subtype. We believe that HBV strains spread within constrained ethnic groups, result in selection pressures that define sequence variability within each subtype. It suggests that particular T cell epitopes are specific for geographical regions, and thus ethnic groups; this may affect the design of immunomodulatory therapies.

Clinical significance of hepatitis B virus genotypes, variants, and mutants

Emerging evidence suggests that hepatitis B virus (HBV) genotypes may influence the rate of spontaneous and interferon-induced hepatitis B e antigen (HBeAg) seroconversion as well as the natural history of liver disease. In contrast, the dinical significance of precore and core promoter variants associated with HBeAg negative liver disease is less certain in light of the many competing host and virologic factors noted in reported studies. HBV surface mutants are primarily associated with prior vaccine or hepatitis B immune globulin exposure and do not appear to have untoward virulence or association with occult HBV infection. Polymerase mutants with reduced drug sensitivity and phenotypic resistance are commonly detected in patients receiving prolonged antiviral therapy and have a variable impact on disease outcomes. The introduction of additional nucleoside/nucleotide analog agents will likely lead to the development of further unique polymerase mutants with varying pathogenicity and cross-resistance to existing drugs.

Detection of hepatitis B virus YMDD variants using mass spectrometric analysis of oligonucleotide fragments

BACKGROUND/AIMS

Mutations in hepatitis B virus (HBV) to lamivudine resistance that arise during prolonged treatment frequently cause amino acid substitutions in the YMDD motif of HBV DNA polymerase. Current methods of detecting such variants are time-consuming, labor intensive, and unsuitable for screening large numbers of samples. Here, we describe the development of a matrix-assisted laser desorption/ionization time of flight mass spectrometry (MALDI-TOF MS) genotyping assay suitable for detecting HBV variants in a sensitive and specific manner.

METHODS

The assay is based on PCR amplification and mass measurement of oligonucleotides containing sites of mutation of the YMDD motif.

RESULTS

The MALDI-TOF MS-based genotyping assay is sufficiently sensitive to detect as few as 100 copies of HBV genome per millilitre of serum, with superior specificity for determining mixtures of wild-type and variant viruses. When sera from 40 patients were analyzed, the MALDI-TOF MS-based assay correctly identified known viral variants and additional viral quasi-species not detected by previous methods, as well as their relative abundance.

CONCLUSIONS

The sensitivity, accuracy and amenability to high-throughput analysis makes the MALDI-TOF MS-based assay suitable for mass screening of HBV infected patients receiving lamivudine, and can help provide further understanding of disease progression and response to therapy.

Hepatitis B virus DNA in liver, serum, and peripheral blood mononuclear cells after the clearance of serum hepatitis B virus surface antigen

The integration of hepatitis B virus (HBV) DNA in the liver of chronic HBV carriers has been documented extensively. However, the status of the viral genome during acute infection has not been assessed conclusively. While HBV DNA sequences are detected often in serum, liver, and peripheral blood mononuclear cells (PBMCs) after the clearance of serum the hepatitis B virus surface antigen (HBsAg), the precise status of the viral genome, and in particular the possible persistence of integrated genomes in PBMCs, has not been established. A highly sensitive PCR-derived assay (Alu-PCR) was employed to re-examine liver and PBMC specimens obtained from patients with acute (n = 19) and chronic (n = 22) hepatitis in whom serum HBsAg was present (n = 12) (HBV-related chronic active hepatitis) or absent with anti-HCV (n = 10) (HCV-related chronic active hepatitis). Viral integration was demonstrated in 3 out of 19 liver specimens from patients with acute hepatitis and 12 out of 12 specimens from patients with chronic hepatitis. Viral integration was also observed in 4 out of 7 PBMC samples from HBV-related chronic active hepatitis patients and 2 out of 10 liver and PBMC samples from HCV-related chronic active hepatitis patients. In one liver specimen from an acute hepatitis patient, HBV DNA was found integrated in the intronic sequence of the tumour necrosis factor (TNF)-induced protein gene; viral integration into cellular sequences was also found in the PBMCs of four HBV-related chronic active hepatitis and two HCV-related chronic active hepatitis. The results demonstrate the early integration of HBV genome during acute viral infections and the persistence of the viral genome in an integrated form in PBMCs.

Inhibitory effect of adefovir and lamivudine on the initiation of hepatitis B virus infection in primary tupaia hepatocytes

Adefovir dipivoxil and lamivudine are two safe and efficacious drugs licensed for the treatment of chronic hepatitis B virus (HBV) infection. Both drugs inhibit the viral polymerase, resulting in a profound suppression of virus production. Blocking the viral polymerase may also affect the initiation of HBV infection, because HBV virions harbor a partially double-stranded genome and productive infection requires completion of viral plus-strand DNA synthesis with subsequent formation of covalently closed circular DNA (cccDNA). To address this issue, we used primary hepatocytes from the tree shrew Tupaia belangeri that were recently shown to be susceptible to HBV infection. Treatment of cells with either drug partially inhibited initial HBV cccDNA formation. Adefovir was more effective than lamivudine, resulting in a 3-fold reduction of RNA synthesis and viral surface antigen production. However, prevention of initial cccDNA formation was incomplete even after combined treatment, whereas de novo synthesis of viral replicative intermediates was completely suppressed. A possible explanation for this observation is the genomic plus-strand gap of less than 200 bases in some virions, limiting the window for antiviral action. In conclusion, nucleos(t)ide analogues can target initial plus-strand DNA repair and reduce but not completely block HBV infection.

Hepatitis B virus downregulates the human interferon-inducible MxA promoter through direct interaction of precore/core proteins

The human MxA protein is an interferon (IFN)-inducible GTPase with proven antiviral activity against diverse viruses. IFN responsiveness is impaired in chronic hepatitis B virus (HBV) infection. Accordingly, initial experiments showed that, in contrast to parental HepG2 cells, when HepG2-derived 2.2.15 liver cells carrying the HBV genome were treated with IFN, they could not synthesize the MxA protein. Furthermore, MxA expression was reduced in HepG2 cells transiently transfected with the HBV genome. To assess whether HBV-encoded precore/core (preC/C) proteins interact with the IFN-signalling pathway, HepG2, Chang and HeLa cells were transfected with preC/C expression plasmids; the levels of signal transducers remained unaffected. Next, full-length and deletion mutants fused to the CAT reporter gene were tested to investigate whether MxA inhibition occurs at the promoter level. In co-transfection experiments, IFN-induced CAT activity was inhibited by preC/C expression in a dose-dependent manner. Analysis of deletion mutants showed that the region affected by the preC/C proteins comprises IFN-stimulated response elements 2 and 3, upstream of the putative start codon of the MxA promoter. In addition, HBV preC/C proteins interacted directly with the MxA promoter, as shown by electrophoretic mobility shift assays. These results demonstrate a mechanism that HBV probably uses to downregulate an element of the IFN-induced host antiviral responses, which accounts for the impairment observed in HBV-infected patients.

A novel stop codon mutation in HBsAg gene identified in a hepatitis B virus strain associated with cryptogenic cirrhosis

AIM: HBsAg is the most important serological marker for acute or chronic hepatitis B. Nevertheless, there were reports of HBsAg-negative infection caused by hepatitis B virus in recent years. We had a patient with crytogenic cirrhosis who was negative for HBsAg, positive for anti-HBs and HBeAg. This paper was to explore the pathogenic and molecular basis of the unusual serological pattern.

METHODS: HBV serologic markers were qualitatively and quantitatively determined. HBV DNA in serum was qualitatively tested using routine Polymerase chain reaction(PCR), and the viral level was determined with real-time fluorescence quantitative PCR. HBsAg gene was amplified and cloned. Four clones were sequenced. The new genomic sequences were compared with GenBank on the DNA level as well as the protein level.

RESULTS: The qualitative results of serological markers were HBsAg(-), anti-HBs(+), HBeAg(+), anti-HBe(-) and anti-HBc(+). The quantitative results of serological marker were HBsAg (S/N): 0.77 (cut off of S/N: ≥ 2.00), HBeAg (S/N): 56.43 (cut off S/N: ≥ 2.10), anti-HBc (S/C_O): 2.03 (cut off of S/C_O: ≤ 1.00). The viral level was as high as 1.54 × 10⁹ copies/ml. Sequencing of the HBsAg gene clones revealed a unique point mutation at nucleotide 336 (C to A), which resulted in a novel stop codon at aa 61. The novel HBsAg gene stop mutation had not been described.

CONCLUSION: The lack of detection of HBsAg in the presence of high viral levels of replication may be caused by the existence of viral genomes harboring point mutations which resulted in stop codon upstream of the “a” determinant in HBsAg gene.

A novel HBV antisense RNA gene delivery system targeting hepatocellular carcinoma

AIM

To construct a novel HBV antisense RNA delivery system targeting hapatocellular carcinoma and study its inhibitory effect in vitro and in vivo.

METHODS

GE7,a 16-peptide specific to EGFR, and HA20,a homologue of N-terminus of haemagglutinin of influenza viral envelope protein, were synthesized and conjugated with polylysin. The above conjugates were organized into the pEBAF-as-preS2, a hepatocarcinoma specific HBV antisense expression vector, to construct a novel HBV antisense RNA delivery system, named AFP-enhancing 4-element complex. Hepatocelluar carcinoma HepG2.2.15 cells was used to assay the in vitro inhibition of the complex on HBV. Expression of HBV antigen was assayed by ELISA. BALB/c nude mice bearing HepG2.2.15 cells were injected with AFP-enhancing 4-element complex. The expression of HBV antisense RNA was examined by RT-PCR and the size of tumor in nude mice were measured.

RESULTS

The AFP-enhancing 4-element complex was constructed and DNA was completely trapped at the slot with no DNA migration when the ratio of polypeptide to plasmid was 1:1. The expression of HBsAg and HBeAg of HepG2.2.15 cells was greatly decreased after being transfected by AFP-enhancing 4-element complex. The inhibitory rates were 33.4 % and 58.5 % respectively. RT-PCR showed HBV antisense RNA expressed specifically in liver tumor cells of tumor-bearing nude mice. After 4 injections of AFP-enhancing 4-element complex containing 0.2 micro g DNA, the diameter of the tumor was 0.995 cm+/-0.35, which was significantly smaller than that of the control groups(2.215 cm+/-0.25, P<0.05).

CONCLUSION

AFP-enhancing 4-element complex could deliver HBV antisense RNA targeting on hepatocarcinoma and inhibit both HBV and liver tumor cells in vitro and in vivo.

Surface, core, and X genes of hepatitis B virus in hepatocellular carcinoma: an in situ hybridization study

BACKGROUND

The incidence of hepatocellular carcinoma (HCC) and the seroprevalence of hepatitis B virus (HBV) in this disease state are significantly higher in South India than in North India. Because data on serologic studies do not project the actual association between the two parameters, this study was undertaken.

METHODS

The prevalence of HBV genes in HCC patients was studied using nonisotopic in situ hybridization. Fifty patients from South India were diagnosed with HCC after performing ultrasound-guided fine-needle aspiration biopsies of liver lesions. The diagnosis was confirmed by cell block studies. Sections cut from paraffin-embedded cell blocks made out of the aspirates were probed with digoxigenin-labeled surface, core, and X regions of the viral genome.

RESULTS

Nuclear integration of the surface gene was observed in 100% (50 of 50), the core gene was positive in 94% (47 of 50), and the X gene was present in 98% (49 of 50) of the cases. An episomal form of the virus was not found. Serum hepatitis B surface antigen was positive only in 48% (12 of 25) of the patients screened.

CONCLUSIONS

We found molecular evidence that HBV is an important contributing factor in the etiology of HCC in South India. In HCC, the S gene of the virus was the most prevalent followed by the X and C genes. Only integrated forms of the viral DNA were observed. Nonisotopic in situ hybridization using multiple regions of the viral genome is a good technique for studying this association. It has an added advantage over polymerase chain reaction, of localization of signals in a tumor cell. Cell blocks made from fine-needle aspirates are ideal for in situ hybridization.

Response of primed human PBMC to synthetic peptides derived from hepatitis B virus envelope proteins: a search for promiscuous epitopes

This investigation was aimed at identifying effective T helper cell epitopes to the hepatitis B virus in humans. A panel of synthetic peptides that represent the hepatitis B virus whole envelope proteins was examined for their capability to stimulate peripheral blood mononuclear cells from human subjects infected with hepatitis B virus naturally. In addition, a large number of subjects were examined and their human leukocyte antigen (HLA) class II allele types were identified to determine whether the helper T cell epitope is specific for a particular HLA allele or 'promiscuous'. The peptides of the amino acid residues 52-67, 110-125, 190-205, and 228-243 appeared to be immunogenic, and particularly, the 52-67 residue was the most promiscuous epitope peptide. These results would contribute to the better understanding of the helper T cell responses to the hepatitis B virus and provide a useful way in designing epitope-based vaccines and future therapeutic strategies.

Impaired response to high-dose interferon treatment in African-Americans with chronic hepatitis C

BACKGROUND/AIMS

The prevalence of hepatitis C virus infection in the USA is higher among African-Americans than among Caucasians. Despite this, little information is available on the course of hepatitis C virus infection in Blacks and in other minority groups. The aim of this retrospective case-control study was to determine the response rate to high dose interferon-alpha treatment in two racial groups with chronic hepatitis C virus infection.

METHODOLOGY

Thirty-one African-Americans and 62 Caucasians with chronic hepatitis C were considered in the study. The subjects were matched for gender, age, presence/absence of cirrhosis, histologic score, and viral genotype. All were treated with interferon-alpha (5 mU/day for 12 months). Three end-points (on-therapy, after 6 months of interferon-alpha, end-of-therapy, at the end of the 12 months of treatment, and off-therapy, 6 months after treatment) were chosen to describe the response to interferon-alpha treatment.

RESULTS

African-Americans had a significantly reduced response to interferon-alpha as compared to Caucasians at all end-points. At the on-therapy end-point, 26% of African-Americans were HCV-RNA negative and had normal transaminases level as compared to 60% of the Caucasians (P < 0.01); at the end-of-therapy end-point the rates were, respectively, 10% and 53% (P < 0.0001). No differences were detected in terms of pretreatment serum ALT, HCV-RNA, iron and ferritin levels or hepatic iron contents between the two groups.

CONCLUSIONS

African-Americans have a reduced response to high-dose interferon-alpha treatment as compared to Caucasians. Both environmental and genetic factors may be implicated in this impaired ability to clear hepatitis C virus infection.

Genotype, serotype, and phylogenetic characterization of the complete genome sequence of hepatitis B virus isolates from Malawian chronic carriers of the virus

Hepatitis B virus (HBV) genotypes have distinct geographical distribution. HBV sequences among hepatitis B carriers in Malawi have not been evaluated thus far. HBsAg serotype and genotype of HBV was determined in 20 serum samples from Malawian chronic HBV carriers, and two complete genomes and 13 entire pre-S2/S genes were sequenced directly. Genotype A HBV isolates were found in all of the samples, and serotype with adw2 and ayw2 were detected in three and 17 samples, respectively. In phylogenetic analyses, two complete genomes were classified into a subgroup A' that was described previously in South African isolates of the virus, and were separated from HBV isolates in Western countries with nucleotide differences ranging from 4.1-6.2%. The separation of subgroup A' was also evident in the tree topology of the entire pre-S1/S2, X and precore/core region, but not evident in the small-S region. The nucleotide divergences in subgroup A' were higher than those among genotype A without subgroup A' in the complete genomes as well as each of four open reading frames. All of the 13 pre-S2/S sequences were classified into the subgroup A', and clustered with known HBV isolates with ayw2 in carriers from South Africa and Zimbabwe. Three amino acids in the pre-S2/S gene were characteristic of subgroup A' with ayw2. In conclusion, unique HBV isolates of subgroup A' with ayw2 are prevalent in Malawi, and subgroup A' with a relatively higher nucleotide diversity may be a HBV isolate characteristic of the indigenous population of some African countries.

Presence of hepatitis B surface antigen mutant G145R DNA in the peripheral blood leukocytes of the family members of an asymptomatic carrier and evidence of its horizontal transmission

An asymptomatic carrier and all six of his family members were detected positive for HBV DNA in their peripheral blood leukocytes (PBL), by polymerase chain reaction. Direct sequencing of the amplified DNA revealed that the HBV DNA from the carrier and his wife was of subtype ayw. Interestingly, the amplified HBV DNA from the five other members of the family was found to be not only of subtype adw but also contained G to A mutation at nucleotide position 587. This indicates the presence of established vaccine escape mutant of the virus (G145R) and suggests two different sources of infection within the family. Southern blot hybridization of EcoR1 digested DNA from PBL indicated presence of HBV DNA, integrated into cellular DNA and also in the form of free viral DNA. The study not only establishes the persistence of surface mutant G145R HBV DNA, within the PBL of HBsAg negative individuals from the non-vaccinated random population, but also suggests possible horizontal transmission of the mutant among the family members although none of the family members has received immunoprophylaxis against HBV or had clinically apparent disease or any other known risk factors of HBV infection. As all of them were seronegative for HBsAg/antiHBc, the presence of G145R mutant in the PBL signaled possibility of spread of the vaccine escape mutant virus by blood transfusion, unsafe injection practices or through sexual root.

Specific cleavage of hepatitis C virus RNA genome by human RNase P

We have found that RNase P from HeLa cells specifically and efficiently cleaves hepatitis C virus (HCV) transcripts in vitro. The evidence includes identification of the 5'-phosphate polarity of the newly generated termini at position A(2860) as well as immunological and biochemical assays. Active cleavage has been shown in five dominant sequences of HCV "quasispecies" differing at or near the position of cleavage, demonstrating that this is a general property of HCV RNA. During the analysis, a second cleavage event was found in the 3' domain of the internal ribosome entry site. We have found that HCV RNA competitively inhibits pre-tRNA cleavage by RNase P, suggesting that HCV RNA has structural similarities to tRNA. This finding sets HCV apart from other pathogens causing serious human diseases and represents the first description of human RNase P-viral RNA cleavage. Here we discuss the possible meaning of these RNase P-accessible structures built into the viral genome and their possible role in vivo. Moreover, such structures within the viral genome might be vulnerable to attack by therapeutic strategies.

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.

In vitro infection of human peripheral blood mononuclear cells by a defective hepatitis B virus with a deletion in the PreS1 region of the viral genome

Previously, we identified a defective hepatitis B virus (HBV) which contains a 183 nucleotide deletion in the PreS1 region of the viral genome affecting the S gene promoter in sera from hepatitis B surface antigen (HBsAg)-negative patients with serum HBV-DNA. The aim of this study was to analyse the infectivity of this mutant. Peripheral blood mononuclear cells (PBMC) from a healthy donor were incubated with serum samples from 2 HBsAg-negative patients with serum HBV-DNA (infected with wild-type and deletion mutant HBV), from an HBsAg carrier (infected with wild-type HBV) and from a healthy donor. After 1 week, HBV-DNA was detected by polymerase chain reaction (PCR) in all supernatants and cells incubated with the HBV-DNA-positive inocula. DNase and trypsin pretreatment confirmed intracellular localization of HBV-DNA in cells. HBV-RNA and covalently closed circular HBV-DNA were also detected in PBMC, indicating that the viral DNA infecting these cells was transcriptionally active. Deletion mutant and wild-type HBV were detected in the supernatants and cells infected with the two HBsAg-negative sera, while only wild-type HBV was detected in the supernatant and cells incubated with the serum from the HBsAg-carrier. In conclusion, this HBV deletion mutant can infect, replicate and release viral particles in in vitro infected PBMC.