HBV genotype B is associated with better response to interferon therapy in HBeAg(+) chronic hepatitis than genotype C

Differences of YMDD mutational patterns, precore/core promoter mutations, serum HBV DNA levels in lamivudine-resistant hepatitis B genotypes B and C

The aims of this study were to investigate the viral differences among lamivudine-resistant hepatitis B virus (HBV) genotypes B and C in vivo. Fifty-three patients carrying lamivudine-resistant HBV were enrolled in this study. HBV genotypes, Levels of alanine aminotransferase (ALT), HBV DNA levels were monitored during therapy. The polymerase and precore/core promoter genes were amplified by polymerase chain reaction and their products were sequenced directly. Among 53 patients resistant HBV genotypes B and C accounted for 41.50% and 58.50%, respectively. The occurrence of reverse transcriptase rt204I mutants was lower in genotype B (36.36%) than that in genotype C (87.10%), whereas rt204V mutants was higher in genotype B (63.64%) than that in genotype C (12.90%). The occurrence of precore mutation (nt1896A) was higher in genotype B (77.27%) than that in genotype C (32.26%). Serum HBV DNA levels after emergence of lamivudine resistance were higher in genotype C (7.71 +/- 0.80 Log copies/mL) compared with genotype B (6.97 +/- 0.77 Log copies/mL). Multivariate analysis identified pretreatment HBV DNA levels, HBeAg status and HBV genotype as independent factors associated with a shorter time to lamivudine resistance(P = 0.035, P = 0.006 and P = 0.001, respectively). Multivariate analysis showed that HBV genotype (P = 0.004) and pretreatment ALT levels (P = 0.01) was independently associated with YMDD mutational patterns. The results showed that the YMDD mutational patterns, precore mutation and serum HBV DNA levels differ between lamivudine-resistant HBV genotypes B and C in vivo. It is valuable for treatment of lamivudine-resistant HBV in clinic.

Role of viral factors in the natural course and therapy of chronic hepatitis B

Hepatitis B virus (HBV) infection is a global health problem that causes a wide spectrum of liver disease, including acute or fulminant hepatitis, inactive carrier state, chronic hepatitis, cirrhosis, and hepatocellular carcinoma (HCC). The pathogenesis of hepatocyte damage associated with HBV is mainly through immune-mediated mechanisms. On the basis of the virus and host interactions, the natural history of HBV carriers who are infected in early life can be divided into four dynamic phases. The frequency, extent, and severity of hepatitis flares or acute exacerbation in the second immune clearance and/or fourth reactivation phase predict liver disease progression in HBV carriers. In the past decade, hepatitis B viral factors including serum HBV DNA level, genotype, and naturally occurring mutants predictive of clinical outcomes have been identified. The higher the serum HBV DNA level after the immune clearance phase, the higher the incidence of adverse outcomes over time. In addition, high viral load, genotype C, basal core promoter mutation, and pre-S deletion correlate with increased risk of cirrhosis and HCC development. As to the treatment of chronic hepatitis B, patients with high HBV DNA level and genotype C or D infection are shown to have a worse response to interferon therapy. In conclusion, serum HBV DNA level, genotype, and naturally occurring mutants are identified to influence liver disease progression and therapy of chronic hepatitis B. More investigations are needed to clarify the molecular mechanisms of the viral factors involved in the pathogenesis of each stage of liver disease and the response to antiviral treatments.

Subgenotypes of hepatitis B virus genotype C do not correlate with disease progression of chronic hepatitis B in Taiwan

BACKGROUND

Hepatitis B virus (HBV) genotype C (HBV/C) has two subgenotypes: HBV/Cs and Ce. The prevalence and clinical implications of subgenotype Cs and Ce in Taiwanese HBV carriers remain unknown.

METHODS

Subgenotypes of HBV/C were determined in 242 Taiwanese HBV carriers with various stages of liver disease. The clinical as well as virologic features between patients with HBV/Cs and HBV/Ce infection were further compared.

RESULTS

HBV/Ce was the predominant subgenotype in Taiwan. The prevalence of HBV/Ce was 93.6% in the inactive carriers group, 84.2% in chronic hepatitis patients, 81.2% in cirrhosis patients, 92.5% in hepatocellular carcinoma (HCC) patients without cirrhosis and 91.9% in HCC patients with cirrhosis. There was no significant difference in the distribution of the HBV/C subgenotypes among patients with different stages of liver disease.

CONCLUSIONS

Subgenotypes of HBV/C may not have a clinical impact on the disease progression of chronic hepatitis B in Taiwan.

Oligonucleotide chip, real-time PCR and sequencing for genotyping of hepatitis B virus

AIM: To compare the oligonucleotide chip, real-time PCR and sequencing for genotyping of hepatitis B virus in Chinese patients with chronic hepatitis B.

METHODS: Mixture of samples with different genotypes and clinical serum samples from 126 chronic hepatitis B patients was tested for hepatitis B virus genotypes by oligonucleotide chip, real-time PCR and sequencing of PCR products, respectively. Clinical performances, time required and costs of the three assays were evaluated.

RESULTS: Oligonucleotide chips and real-time PCR detected 1% and 0.1% genotypes, respectively, in mixed samples. Of the 126 clinical samples from patients with chronic hepatitis B, genotype B was detected in 41 (33%), 41 (33%) and 45 (36%) samples, and genotype C in 76 (60%), 76 (60%) and 81 (64%) samples, by oligonucleotide chip, real-time PCR and sequencing, respectively. Oligonucleotide chip and real-time PCR detected mixed genotypes B and C in 9 samples. Real-time PCR was the rapidest and cheapest among the three assays.

CONCLUSION: Oligonucleotide chip and real-time PCR are able to detect mixed genotypes, while sequencing only detects the dominant genotype in clinical samples.

Molecular testing in the diagnosis and management of chronic hepatitis B

Hepatitis B virus (HBV) is an enveloped virus with a small (3.2-kb) partially double-stranded DNA genome that causes acute and chronic infections. The impact of these infections on public health worldwide is enormous, with an estimated prevalence of 2 billion acute infections and 360 million chronic infections globally. This review focuses on chronic hepatitis B and the molecular assays used in its diagnosis and management. Background information, including that about features of the hepatitis B virion, viral replication, and epidemiology of infection, that is important for understanding chronic hepatitis B and molecular diagnostic tests for HBV is provided. To facilitate an understanding of the utility of molecular testing for chronic hepatitis B, the four stages of chronic hepatitis B infection that are currently recognized, as well as an additional entity, occult hepatitis B, that can be diagnosed only by sensitive nucleic acid amplification methods, are reviewed in detail, including available therapeutic agents. The molecular diagnostic content focuses on tests for HBV DNA quantification, genotyping, and mutation detection (including precore/core promoter and antiviral resistance mutations). The discussion of these tests encompasses their current utility and performance characteristics, drawing from current clinical guidelines and other studies from the literature. In recognition of the continual evolution of this field, the final section describes emerging molecular markers with future diagnostic potential.

Hepatitis B virus genotypes in Europe

There are eight genotypes of hepatitis B virus (HBV). Most genotypes can be further divided into subgenotypes. HBV genotypes influence the course of disease and treatment, and show geographic preferences. In Europe, A and D are the main genotypes found. Genotype A is more prevalent in northern Europe, where genotype D is mainly found in countries surrounding the Mediterranean Sea and in Eastern Europe. Subgenotype A2 is the dominant subgenotype in Europe, but the geographic prevalence of the four subgenotypes found in genotype D is not yet clear. On treatment with interferon HBV, genotype A, compared to genotype D, showsbetter virological response and in a large proportion of patients, even development of anti-HBs. However, in the first year of treatment with lamivudine, higher rates of emergence of YMDD variants are observed in genotype A. This work summarizes the current knowledge on HBV genotypes in countries with low and intermediate HBV carriership from Europe.

Hepatitis B virus genotypes and subgenotypes in China

Eight Hepatitis B virus (HBV) genotypes (A to H) have been identified based on an intergenotype divergence of 8% or more in the entire nucleotide sequence. Subgenotypes have also been identified in different HBV genotypes. As a highly endemic area for HBV infection, the prevalence of chronic HBV infection in China is between 8 and 20% of the general population. Genotypes B and C were identified as the most common HBV strains and account for approximately 95% of Chinese patients. Further study confirmed all genotype B strains belong to subgenotype Ba. Two of genotype C subgenotypes, C1 (Cs) and C2 (Ce), were found in China and they showed different geographic distributions. Genotype A was very rarely found, while genotypes E, F, G and H have not beenreported until now. Two types of HBV C/Drecombinant viruses have been identified in west China and distinct geographic and ethnic distributions were observed. Significant differences were observed (P < 0.001) in the prevalence of A1896 and T1762/A1764 mutations among HBV Ba, C1 and C2 subgenotypes in Chinese patients. Accumulating evidence showed the response rate to antiviral therapy in Chinese patients is higher in genotype B than genotype C patients on interferon treatment, but no difference was observed on nucleoside/nucleotide analog treatment.

Appropriate use of interferon for treatment of chronic hepatitis B

Hepatitis B is not only a preventable but now treatable disease. Five drugs have been approved for the treatment of chronic hepatitis B virus (HBV) infection: standard interferon-alpha (IFN), pegylated IFN, lamivudine, adefovir dipivoxil and entecavir. Among these agents, the responses to interferon therapy are invariably influenced by both host and viral factors. Therefore, understanding these factors is important for practicing hepatologists, and it may help design individualized medicine for the treatment of chronic hepatitis B. HBV genotypes affect the disease progression and outcomes of HBV-related chronic liver disease, as well as the response to antiviral treatments. Existing data indicate a better sustained response to standard IFN-alpha in HBeAg positive genotype B patients than genotype C patients, and in genotype A patients than genotype D patients. Nevertheless, conflicting results exist regarding the response to pegylated IFN, and more studies are needed. As to HBV genetic polymorphisms, a recent study showed that an IFN sensitivity-determiningregion may not exist within the whole genome of HBV subgenotype Ba, and host factors as well as virus-host interactions may be more important than viral factors alone in determining the treatment outcomes with IFN. Regarding host genetic polymorphisms, single nucleotide polymorphisms within eukaryotic translation initiation factor 2 and MxA promoter regions may be associated with the responsiveness to standard IFN-alpha treatment in patients with HBeAg positive chronic hepatitis B. In the foreseeable future, individualized chronic hepatitis B treatment algorithms should be tailored to host (immune status, ALT level and genomic polymorphisms), virus (HBeAg status, HBV DNA level, genotype, precore/basal core promoter mutants and pre-S deletion mutant) as well as liver disease status (hepatitis activity and fibrosis stage).

Distribution and characteristics of hepatitis B virus genotype C subgenotypes in China

Genetic diversity within the same hepatitis B virus (HBV) genotype indicates the presence of several subgenotypes. We have found that genotype C is the most common in China, and this study aimed to determine the geographical distribution and characteristics of HBV-C subgenotypes in the country. A cohort of 534 patients with chronic HBV genotype C infection, collected across China, was analysed by nucleotide sequencing or polymerase chain reaction-restriction fragment length polymorphism. HBV-C1/Cs (n = 112, 21%) and HBV-C2/Ce (n = 397, 74%) were the most common HBV-C subgenotypes and showed different geographical distribution in China. No significant differences were found between patients infected with HBV-C1 and HBV-C2 when comparing liver function tests, hepatitis B e antigen positive rate and clinical manifestations. We identified two other types of HBV-C provisionally designated as HBV-CD1 and HBV-CD2, which have particular virological features and clustered in one geographic area. These two types of C/D hybrids have emerged through recombination with genotype D and encode serotype ayw2 hepatitis B surface antigen. In conclusion, there are at least four subtypes of HBV genotype C: subgenotypes C1, C2 and two types of C/D recombinants CD1 and CD2 in China, which have a distinct geographic distribution. Whether HBV-C subgenotypes differ in their impact on liver disease progression requires prospective studies.

No significant differences in histology and response to interferon treatment in hepatitis B carriers of genotypes C and recombinant B

Hepatitis B virus (HBV) genotypes B and C are most prevalent in China and genotype B is found exclusively in recombination with the pre-C/C gene of genotype C. We investigated whether there is a difference in clinical relevance between the two genotypes sharing the same pre-C/C gene. Thus, we determined the genotype of HBV among consecutive HBeAg-positive patients with tailored interferon-alpha (IFN-alpha) therapy, and the demographic, baseline clinical characteristics and treatment results were compared between them. The median values of alanine transaminase (ALT) were 4.5 and 5.0 times the upper limit of normal (P = 0.419), HBV-DNA levels were 1.4 x 10(7) and 1.5 x 10(7)copies/mL (P = 0.829), mean scores of necroinflammatory histological activity 9.8 and 10.44 (P = 0.105) and fibrotic activity 2.64 and 2.86 (P = 0.227) in genotype B and C patients, respectively. The end-of-treatment response was 42.7% and 39.0% (P = 0.531) with mean tailored treatment months of 8.28 and 9.34 (P = 0.160), and the sustained response 43.4% and 37.5% (P = 0.31) at the end of a 12-month follow-up period in genotype B and C patients, respectively. These results remained similar when follow-up was extended to nearly 3 years. In conclusion, no significant differences in clinical characteristics and response to IFN-alpha between genotypes B and C were found, probably, because both types shared a common pre-C/C encoding region.

Future prospectives for the management of chronic hepatitis B

Chronic hepatitis B virus infection affects about 400 million people around the globe and causes approximately one million deaths a year. Since the discovery of interferon-α as a therapeutic option the treatment of hepatitis B has evolved fast and management has become increasingly complicated. The amount of viral replication reflected in the viral load (HBV-DNA) plays an important role in the development of cirrhosis and hepatocellular carcinoma. The current treatment modalities for chronic hepatitis B are immunomodulatory (interferons) and antiviral suppressants (nucleoside and nucleotide analogues) all with their own advantages and limitations. An overview of the treatment efficacy for both immunomodulatory as antiviral compounds is provided in order to provide the clinician insight into the factors influencing treatment outcome. With nucleoside or nucleotide analogues suppression of viral replication by 5-7 log₁₀ is feasible, but not all patients respond to therapy. Known factors influencing treatment outcome are viral load, ALT levels and compliance. Many other factors which might influence treatment are scarcely investigated. Identifying the factors associated with response might result in stopping rules, so treatment could be adapted in an early stage to provide adequate treatment and avoid the development of resistance. The efficacy of compounds for the treatment of mutant virus and the cross-resistance is largely unknown. However, genotypic and phenotypic testing as well as small clinical trials provided some data on efficacy in this population. Discontinuation of nucleoside or nucleotide analogues frequently results in viral relapse; however, some patients have a sustained response. Data on the risk factors for relapse are necessary in order to determine when treatment can be discontinued safely. In conclusion: chronic hepatitis B has become a treatable disease; however, much research is needed to tailor therapy to an individual patient, to predict the sustainability of response and determine the best treatment for those failing treatment.

Difference in T helper responses during hepatitis flares in hepatitis B e antigen (HBeAg)-positive patients with genotypes B and C: implication for early HBeAg seroconversion

The underlying mechanisms for earlier hepatitis B e antigen (HBeAg) seroconversion in patients with chronic hepatitis B virus (HBV) genotype B when compared with genotype C are unknown. We aimed to determine whether there were any differences in the T helper (Th) responses during hepatitis flares in HBeAg-positive patients with genotypes B and C. Proliferative response measured by (3)H-thymidine uptake and Th responses measured by Enzyme-Linked Immunosorbent Spot assays for interleukin (IL)-2, interferon-gamma (IFN-gamma), IL-4, IL-5 and IL-10 were performed in 10 patients with genotype B and 10 with genotype C with hepatitis flares. HBV genotypes, core promoter, precore mutations, sequence of HBV core region and HBV DNA levels were determined. There was no difference in the HBV DNA levels during hepatitis flares between patients with genotypes B and C. Patients with genotype B had a significantly higher number of IFN-gamma producing cells [with hepatitis B core antigen (HBcAg) stimulation] and lower number of IL-10 producing cells (with HBcAg and HBeAg stimulation) compared with patients with genotype C (P = 0.011, =0.043, <0.001 respectively). There was a trend (P = 0.058) that patients with genotype B had a higher cumulative rate of HBeAg seroconversion. Patients with precore mutants also had a significantly higher number of IFN-gamma producing cells (with HBcAg stimulation) and lower number of IL-10 producing cells (with HBeAg stimulation) compared to patients without precore mutant (P = 0.038, =0.016 respectively). HBV genotype B induces a greater Th1 and lesser Th2 response than genotype C. This provides immunologic evidence for the higher chance of HBeAg seroconversion in patients with genotype B.

Study on the function of circulating plasmacytoid dendritic cells in the immunoactive phase of patients with chronic genotype B and C HBV infection

Hepatitis B virus (HBV) infection induces a wide range of chronic liver injury. The mechanism by which HBV evades the immune surveillance system remains obscure. Plasmacytoid dendritic cells (pDCs) seem to be the major endogenous interferon (IFN)-alpha producers and represent one of the most important cell types in the regulation of antiviral innate immunity; however, the phenotype and function of pDCs in patients infected by HBV with different genotypes are yet to be determined. The aim of this study was to investigate the differences in the numbers and function of peripheral blood pDCs in the immune clearing phase of chronic HBV infection with genotypes B and C. Fifty-six patients with persistent HBV infection were included in this study, with 19 age-matched healthy subjects being used as a control group. The frequencies of pDCs were analysed by flow cytometry, and the IFN-alpha produced by peripheral blood mononuclear cells (PBMCs) after stimulation with cytidine phosphate guanosine (CpG) oligonucleotides for 24 h was determined by enzyme-linked immunosorbent assay. The genotypes of HBV were detected by polymerase chain reaction and hybridization. The results showed that the frequency and IFN-alpha-producing capacity of peripheral blood pDCs were dramatically reduced and relatively inversely correlated with the level of serum alanine aminotransferase in both groups of patients with chronic genotype B and C HBV infection. A lower reduction of IFN-alpha production by CpG-stimulated PBMCs was found in patients with genotype C than in those with genotype B in the phase of immune clearance. In conclusion, the frequency and IFN-alpha-producing capacity of peripheral blood pDCs were dramatically reduced in the immunoactive phase of chronic hepatitis B (CHB). Furthermore, the lower reduction in IFN-alpha production in patients with genotype C than in those with genotype B may correlate with the outcome of antiviral treatment in CHB patients and the progression of liver inflammation.

Replicative homeostasis III: implications for antiviral therapy and mechanisms of response and non-response

While improved drug regimens have greatly enhanced outcomes for patients with chronic viral infection, antiviral therapy is still not ideal due to drug toxicities, treatment costs, primary drug failure and emergent resistance. New antiviral agents, alternative treatment strategies and a better understanding of viral pathobiology, host responses and drug action are desperately needed. Interferon (IFN) and ribavirin, are effective drugs used to treat hepatitis C (HCV), but the mechanism(s) of their action are uncertain. Error catastrophe (EC), or precipitous loss of replicative fitness caused by genomic mutation, is postulated to mediate ribavirin action, but is a deeply flawed hypothesis lacking empirical confirmation. Paradoxically ribavirin, a proven RNA mutagen, has no impact on HCV viraemia long term, suggesting real viruses, replicating in-vitro, as opposed to mathematical models, replicating in-silico, are likely to resist EC by highly selective replication of fit (~consensus sequence) genomes mediated, in part, by replicative homeostasis (RH), an epicyclic mechanism that dynamically links RNApol fidelity and processivity and other viral protein functions. Replicative homeostasis provides a rational explanation for the various responses seen during treatment of HCV, including genotype-specific and viral load-dependent differential response rates, as well as otherwise unexplained phenomena like the transient inhibition and rebound of HCV viraemia seen during ribavirin monotherapy. Replicative homeostasis also suggests a primarily non-immunological mechanism that mediates increased immune responsiveness during treatment with ribavirin (and other nucleos(t)ide analogues), explicating the enhanced second-phase clearance of HCV ribavirin promotes and, thus, the apparent immunomodulatory action of ribavirin. More importantly, RH suggests specific new antiviral therapeutic strategies.

Effect of lowering HBV DNA levels by initial antiviral therapy before adding immunomodulator on treatment of chronic hepatitis B

BACKGROUND

Lower hepatitis B virus DNA (HBV DNA) levels are associated with better responses in chronic hepatitis B (CHB). It is unclear whether an initial phase of antiviral treatment to lower HBV DNA levels before adding immunomodulator therapy is more effective than the strategy of using immunomodulators from the beginning.

AIM

The aim of the study was to compare the efficacy of lamivudine followed by pegylated-interferon (peg-IFN) therapy with placebo followed by peg-IFN therapy in HBeAg-positive CHB patients.

PATIENTS AND METHODS

Sixty-three treatment-naive HBeAg-positive patients with histologically proven CHB and alanine aminotransferase (ALT) > 1.2 x upper limit of normal (ULN) received placebo for 4 wk followed by peg-IFN 1.0 mug/kg/wk for next 24 wk (group A, N = 27; age 32 +/- 11 yr; M:F = 25:2) or lamivudine 100 mg per day for 4 wk followed by peg-IFN 1.0 mug/kg/wk for next 24 wk (group B, N = 36; age 32.5 +/- 10.5 yr; M:F = 31:5). Patients were followed for next 24 wk after completion of treatment. Biochemical and virologic responses were assessed at weeks 4, 28, and 52 and analysis was done on intention-to-treat basis.

RESULTS

At wk 4, mean +/- SD of log change in DNA from baseline was 0.2594 +/- 1.7873 in group A and 1.2186 +/- 1.6347 in group B, respectively (P = 0.032). At week 28, undetectable HBV DNA was seen in eight (29.6%) and 16 (44.4%) patients in groups A and B, respectively (P= 0.298). At week 28, HBeAg loss occurred in eight (29.6%) in group A and 15 (41.7%) in group B (P = 0.43). Six months posttherapy, at week 52, undetectable HBV DNA was seen in four (14.8%) and 18 (50%) in groups A and B, respectively (P = 0.028) and HBeAg loss was maintained in four (14.8%) and 14 (38.9%) (P = 0.05) patients. Normal ALT was seen in five (18.5%) and 10 (27.8%) at week 28 (P = 0.552) and five (18.5%) and 13 (36.1%) at week 52 (P = 0.159) in groups A and B, respectively. There was a significant correlation among achievement of HBeAg loss, anti-HBe appearance, and undetectable HBV DNA levels at week 28 (P = 0.008) and 52 (P < 0.001) and HBV DNA levels at week 4.

CONCLUSIONS

The strategy of using an antiviral initially to decrease HBV DNA levels before adding an immunomodulatory agent leads to improved sustained virological response as compared with using immunomodulator from the start.

Hepatitis B virus genotype B is associated with better response to thymosin alpha1 therapy than genotype C

Hepatitis B virus (HBV) genotype has been reported to correlate with response to interferon treatment in several studies. The relationship between HBV genotype and thymosin alpha1 (T-alpha1) treatment is unknown. We retrospectively examine HBV genotypes, precore and core promoter mutations in patients treated with Talpha1 and analyse the correlation between complete response [alanine aminotransferase (ALT) normalization plus seroclearance of HBeAg and HBV-DNA] and HBV genotype. It consisted 98 patients with chronic hepatitis B randomly allocating to three groups: (i) T6 group (n = 32) received a 26-week course of Talpha1 1.6 mg two times a week; (ii) T12 group (n = 34) received the same regimen as T6 group, but Talpha1 therapy extended for 52 weeks; (iii) T0 group (n = 32) served as a control and was followed up for 18 months without specific treatment. Stepwise logistic regression analysis showed that genotype (OR, 3.747; 95% CI, 1.066-13.170; P = 0.039), precore mutation (OR, 6.285; 95% CI, 1.874-21.086; P = 0.003) and Talpha-1 treatment (OR, 12.045; 95% CI, 2.220-65.354; P = 0.004) as independent factors associated with complete response. The complete response of Talpha-1 therapy was higher in patients with genotype B compared to patients with genotype C (52%vs 24%; P = 0.036) and in patients with precore mutation (64%vs 19%; P = 0.002). In conclusion, genotype, presence of precore mutation and Talpha-1 therapy were independent predictors to complete response. Genotype B, compared to genotype C, is associated with a higher response rate to T-alpha1 therapy.

Molecular analysis of hepatitis B virus isolates in Mexico: Predominant circulation of hepatitis B virus genotype H

AIM: To determine the genotypes in Mexican hepatitis B virus (HBV) isolates and characterize their precore and core promoter mutations.

METHODS: Forty-nine HBV isolates of Mexico obtained from sera of 15 hepatitis patients, 6 hemodialysis patients, 20 men seeking HIV testing, and 8 AIDS patients were analyzed. HBV isolates were amplified by PCR, and genotyped by line probe assay (INNO-LiPA HBV Genotyping; INNOGENETICS N V, Ghent, Belgium). HBV genotype confirmation was performed by DNA sequencing part of the sAg region. Precore and core promoter mutation characterization was performed by line probe assay (INNO-LiPA HBV PreCore; INNOGENETICS N V, Ghent, Belgium).

RESULTS: Overall, HBV genotype H was found in 37 (75.5%) out of the 49 isolates studied. HBV genotypes G, A, and D were found in 5 (10.2%), 4 (8.2%), and 3 (6.1%) isolates, respectively. HBV genotype H was predominant in isolates from hemodialysis patients (100%), hepatitis patients (80%), and men seeking HIV testing (75%), and accounted for half of infections in AIDS patients (50%). Six (12.2%) out of the 49 HBV isolates showed both wild type and mutant populations at precore codon 28. These mixed wild type and precore mutant populations were observed in one HBV genotype A isolate and in all HBV genotype G isolates. A dual variant core promoter mutation was observed in 1 (2%) of the isolates, which was genotype H.

CONCLUSION: HBV genotype H is highly predominant in HBV isolates of Mexico followed by genotypes G, A and D. A low frequency of precore and core promoter mutations is observed in HBV Mexican isolates.

Distribution of hepatitis B virus genotypes: phylogenetic analysis and virological characteristics of genotype C circulating among HBV carriers in Kolkata, Eastern India

AIM

To evaluate the genotype distribution of hepatitis B virus (HBV) in Eastern India and to clarify the phylogenetic origin and virological characteristics of the recently identified genotype C in this region.

METHODS

Genotype determination, T1762/A1764 mutation in the basal core promoter (BCP) and A1896 mutation in the precore region of 230 subjects were determined by restriction fragment length polymorphism method (RFLP) and the result was confirmed by direct sequencing.

RESULTS

The predominant genotypes D (HBV/D) and A (HBV/A) were detected in 131/230 (57%) and 57/230 (25%) samples. In addition, genotype C (HBV/C) was detected in 42/230 (18%) isolates. Surface gene region was sequenced from 45 isolates (27 HBV/C, 9 HBV/A and 9 HBV/D). Phylogenetic analysis revealed that all of the HBV/C sequences clustered with South East Asian subgenotype (HBV/Cs). The sequence data showed remarkable similarity with a Thai strain (AF068756) (99.5% +/- 0.4% nucleotide identities) in 90% of the genotype C strains analyzed. T1762/A1764 mutation in BCP region, associated with high ALT was significantly higher in HBeAg negative isolates than HBeAg positive isolates. Frequency of A1896 mutation leading to HBeAg negativity was low.

CONCLUSION

The present study reports the genotypic distribution and the characteristics of partial genome sequences of HBV/C isolates from Eastern India. Low genetic diversity and confinement of HBV/C in Eastern India possibly indicate a recent, limited, spread in this region. Genotype C with T1762/A1764 mutation has been reported to increase the risk for hepatocellular carcinoma; therefore genotype C carriers in Eastern India should be carefully monitored.

Functional and clinical significance of hepatitis D virus genotype II infection

Hepatitis D virus (HDV) infection is one of the important etiologies of fulminant hepatitis and may aggravate the clinical course of chronic HBV infection to cirrhosis and liver failure. HDV was classified into three genotypes. Recent molecular phylogenetic analysis of HDV suggests at least seven major clades. The genotype I HDV is widely spread, genotype II is found in East Asia and genotype III HDV is prevalent in South America. The genomic size is 1682-1685 nucleotides (nt) for genotype II, and 1676 nt for genotype IV (IIb). The divergence in HDV nucleic acid sequences between genotype II and other genotypes varies from 13.8% to 35.3%. The divergences in the HDAg-coding region may range from 17.8% to 29.8% between genotype II and other genotypes. There is no genotypic or size restriction on the interactions of either the small or the large hepatitis delta antigens (HDAgs) between genotypes I and II, and there is also no genotypic incompatibility during co-package of HDAgs of different genotypes into virus like particles. There appears no apparent universal genotypic restriction of the transactivation of genotype I HDV RNA replication by small HDAg of genotype II. In contrast, there appears more genotypic restriction for genotype I small HDAgs to transactivate genotype II HDV RNA replication. Of the functional domains of HDAg, the 19 amino acids at the carboxyl-end of the large HDAg show the greatest divergences (70%-80%) between genotypes I and II. The viral packaging efficiencies of genotype I HDV isolates are usually higher than those of genotype II. The 19 amino acids at the carboxyl-end seem to be the most important determinant for viral packaging efficiencies. The editing efficiencies of the genotype I HDV are also higher than those of the genotype II. Genotype II HDV infection is relatively less frequently associated with fulminant hepatitis at the acute stage and less unfavorable outcomes [cirrhosis or hepatocellular carcinoma (HCC)] at the chronic stage as compared to genotype I. It appears that the clinical manifestations and outcomes of patients with genotype IV (IIb) HDV infection are more like those of patients with genotype II HDV infection. Persistent replication of HBV or HDV was associated with higher adverse outcomes (cirrhosis, HCC or mortality) compared to those who cleared both viruses from the sera. HBV of the genotype C is also a significant factor associated with adverse outcomes (cirrhosis, HCC or mortality) in patients with chronic hepatitis D in addition to genotype I HDV and age. However, most patients with chronic HDV infection have low or undetectable hepatitis B virus DNA levels. During longitudinal follow-up, genotype I HDV is the most important determinant associated with survival.

Detection of rtN236T and rtA181V/T mutations associated with resistance to adefovir dipivoxil in samples from patients with chronic hepatitis B virus infection by the INNO-LiPA HBV DR line probe assay (version 2)

The nucleotide analog adefovir dipivoxil (ADV) is an effective antiviral treatment for chronic hepatitis B virus (HBV) infection, with resistance to ADV estimated to occur less frequently than resistance to lamivudine treatment. The detection of ADV resistance mutations is necessary during therapy to monitor and anticipate possible treatment failure. The INNO-LiPA HBV DR v2 (LiPA; Innogenetics, Ghent, Belgium) is a DNA hybridization line probe assay for the detection of HBV polymerase mutations associated with resistance to lamivudine and ADV. Evaluation of this assay to detect ADV resistance mutations was performed by analyzing 38 patients treated with ADV. Serial samples taken at 6-month intervals during treatment were available for most patients. A total of 124 samples were analyzed by both LiPA and sequencing. By LiPA analysis, 12 patients (31.5%) were found to have mutations associated with resistance to ADV (rtA181V/T and/or rtN236T). This contrasted with sequence analysis, which found nine patients (24%) with either or both mutations. Twice as many samples were rtN236T positive by LiPA (18 of 124) compared to sequence analysis (9 of 124). LiPA detected the rtN236T mutation at least 6 months earlier than its detection by sequencing in patients for whom consecutive serum samples were available. Although less sensitive, sequencing has the advantage of providing information on other polymerase mutations not represented on LiPA strips. The INNO-LiPA HBV DR v2 assay is a very sensitive and specific assay for the detection of the rtN236T mutation associated with resistance to ADV.

Hepatitis B virus genotypes and G1896A precore mutation in 486 Spanish patients with acute and chronic HBV infection

This study aims to determine the prevalence of hepatitis B virus (HBV) genotypes (A-F) and their association with the G1896A precore mutation in 486 patients positive for HBV surface antigen. Genotypes were determined by RFLP and precore mutation by real-time PCR. Genotypes D (48.1%) and A (39.5%) were the most common, followed by F (4.1%) and B, C and E (<1%). The A to D ratio (A:D) was 1.4 in HBeAg+ chronic hepatitis B (CHB), 0.6 in HBeAg- CHB and 1.4 in HBeAg- inactive carriers. Distribution of these genotypes was different between HBeAg+ CHB and HBeAg- CHB (P = 0.02), and between HBeAg- CHB and HBeAg- inactive carriers (P = 0.009). Genotype A was the most prevalent in HBeAg+ CHB with elevated alanine aminotransferase (ALT) (68.6%) and genotype D in HBeAg+ CHB with fluctuating ALT (60.7%). There was a difference in genotype prevalence between chronic and acute infection (P = 0.03). The precore mutant correlated with high levels of HBV-DNA in genotype d HBeAg- CHB. Genotype D is not as highly prevalent in Spanish patients as would be expected in a Mediterranean area. The unequal prevalence of genotypes between acute and chronic infection suggests that genotype A is associated with a higher tendency to cause chronic infection.

Quantitative HBV DNA levels as an early predictor of nonresponse in chronic HBe-antigen positive hepatitis B patients treated with interferon-alpha

To reduce unnecessary exposure to treatment, physicians must decide at an early stage whether continuation of treatment has a reasonable chance of success for the individual patient. The objectives of our study were to evaluate the previously described quantitative hepatitis B e antigen (HBeAg) measurements vs quantitative hepatitis B virus (HBV) DNA measurements for prediction of nonresponse and response in interferon (IFN)-alpha treated HBeAg positive chronic HBV patients. Serum HBV DNA and HBeAg levels were assessed at baseline and weeks 8 and 12. For each test (HBV DNA level at baseline, HBV DNA decrease between baseline and weeks 8 and 12, or the combination of these two, as well as HBeAg level at baseline, HBeAg decrease between baseline and weeks 8 and 12, and the combination of these two), we calculated the positive predictive value, negative predictive value, sensitivity and specificity. Monitoring with quantitative HBV DNA levels (area under ROC 0.87) was superior to monitoring with quantitative HBeAg levels (0.76, P < 0.05). Step-wise logistic regression identified HBV DNA at baseline and decrease in HBV DNA from baseline to week 12, as independent predictors of response. The overall test performance of predicting nonresponse (predictive value 100%) was best for log HBV DNA testing at week 12 compared with testing at week 8 due to a better prediction of sustained response (46%vs 38%) and lower misidentification of nonresponse (39%vs 54%). This study showed that quantitative HBV DNA testing at baseline in combination with a decrease between baseline and week 12 has a high predictive value for identifying patients who have virtually no chance of reaching a sustained response with IFN therapy.

Established and emerging therapies for the treatment of viral hepatitis

Patients who are chronically infected with either hepatitis B or C viruses run the risk of developing cirrhosis and hepatocellular carcinoma in later life. Antiviral treatment offers the only means of interrupting this progression. To date, recombinant interferon alpha and the nucleos(t)ide analogues lamivudine and adefovir dipivoxil are the only licensed drugs for the treatment of chronic hepatitis B, whilst recombinant or pegylated interferons in combination with ribavirin are the ones used for chronic hepatitis C virus infections. The efficacy of these treatments, reasons for treatment failure, drug resistance and future options are discussed in the present review.

Factors related to post-treatment relapse in chronic hepatitis B patients who lost HBeAg after lamivudine therapy

BACKGROUND AND AIM

It is uncertain if a patient's lamivudine response after HBeAg loss is durable. In Korean chronic hepatitis B patients, the relapse rate is high after termination of lamivudine therapy for patients with HBeAg loss. We evaluated the factors related to relapse in chronic hepatitis B patients with HBeAg loss after lamivudine therapy.

METHODS

A total of 132 chronic hepatitis B patients, who initially had HBeAg and did not have decompensated features, were analyzed in this study. These patients lost the HBeAg after lamivudine therapy and then their therapy was stopped. Post-treatment serum alanine aminotransferase (ALT), HBeAg, anti-HBe and hepatitis B virus (HBV) DNA were monitored until relapse.

RESULTS

Seventy-five patients relapsed (cumulative relapse rate: 56% at 6 months). Upon univariate analysis, the factors of age, serum total bilirubin, presence of anti-HBe after HBeAg loss, and the duration of additional lamivudine therapy after HBeAg loss were associated with relapse. Upon multivariate analysis, older age, a higher serum total bilirubin and the shorter duration of additional lamivudine therapy were significant risk factors for relapse. Patterns of relapse were the re-elevation of ALT, re-emergence of HBV DNA (69 patients) and reappearance of HBeAg (55 patients).

CONCLUSIONS

To prevent relapse in patients with chronic hepatitis B infection after lamivudine therapy, age and serum bilirubin level of patients as well as a prolonged duration of additional lamivudine therapy should be considered.

Therapeutic implications of hepatitis B virus genotypes

BACKGROUND/AIMS

Hepatitis B virus (HBV) is a global health problem. In addition to the implementation of universal hepatitis B vaccination, effective and individualized treatment of chronic hepatitis B to prevent progression into end-stage liver diseases and hepatocellular carcinoma is still needed. HBV has been designated eight genotypes (A-H) based on genome sequence divergence. The epidemiology of HBV genotypes and their implications on the responses to antiviral therapy have become increasingly recognized in both Asian and Western countries.

METHODS

Published data are thus reviewed.

RESULTS

Each genotype has its distinct geographical and ethnic distribution. Genotypes A and D occur frequently in Africa, Europe, and India, while genotypes B and C are prevalent in Asia. Genotype E is restricted to West Africa, and genotype F is found in Central and South America. The distribution of genotypes G and H is less clear. Accumulating evidence indicates a better sustained response to conventional interferon in patients with genotype B than those with C, and in patients with genotype A than those with D. In contrast, conflicting results exist regarding the response to pegylated interferon. On the other hand, the therapeutic responses to nucleoside/nucleotide analogues are comparable among patients with different HBV genotypes. The impact of HBV subgenotypes, mixed genotype infections, and recombinants of different genotypes on the response to antiviral treatments awaits further examinations.

CONCLUSION

Remarkable clinical and pathogenic differences do exist among HBV genotypes; however, researches on molecular and virologic mechanisms underlying the clinical phenotypes of different HBV genotypes are urgently needed.

VP22 fusion protein-based dominant negative mutant can inhibit hepatitis B virus replication

AIM: To investigate the inhibitory effect of VP22 fusion protein-based dominant negative (DN) mutant on Hepatitis Bvrus (HBV) replication.

METHODS: Full-length or truncated fragment of VP22 was fused to C terminal of HBV core protein (HBc), and subcloned into pcDNA3.1 (-) vector, yielding eukaryotic expression plasmids of DN mutant. After transfection into HepG2.2.15 cells, the expression of DN mutant was identified by immunofluorescence staining. The inhibitory effect of DN mutant on HBV replication was indexed as the supernatant HBsAg concentration determined by RIA and HBV-DNA content by fluorescent quantification-PCR (FQ-PCR). Meanwhile, metabolism of HepG2.2.15 cells was evaluated by MTT colorimetry.

RESULTS: VP22-based DN mutants and its truncated fragment were expressed in HepG2.2.15 cells, and had no toxic effect on host cells. DN mutants could inhibit HBV replication and the transduction ability of mutant-bearing protein had a stronger inhibitory effect on HBV replication. DN mutants with full length of VP22 had the strongest inhibitory effect on HBV replication, reducing the HBsAg concentration by 81.94%, and the HBV-DNA content by 72.30%. MTT assay suggested that there were no significant differences in cell metabolic activity between the groups.

CONCLUSION: VP22-based DN mutant can inhibit HBV replication effectively.

Novel type of hepatitis B virus mutation: replacement mutation involving a hepatocyte nuclear factor 1 binding site tandem repeat in chronic hepatitis B virus genotype E

The genetic diversity of hepatitis B virus (HBV) strains has evolved through mutations such as point mutations, deletions or insertions, and recombination. We identified and characterized a novel type of mutation which is a complex of external insertion, deletion, and internal duplication in sequences from one of six patients with chronic hepatitis B virus genotype E (HBV/E). We provisionally named this mutation a "replacement mutation"; the core promoter upstream regulatory sequence/basic core promoter was replaced with a part of the S1 promoter covering the hepatocyte nuclear factor 1 (HNF1) binding site, followed by a tandem repeat of the HNF1 site. A longitudinal analysis of the HBV population over 6 years showed the clonal change from wild-type HBV/E to replacement-mutant type, resulting in a lower hepatitis B (HB) e antigen titer, a high HBV DNA level in serum, and progression of liver fibrosis. In an in vitro study using a replication model, the replacement-mutant HBV showed higher replication levels than the wild-type HBV/E replicon, probably mediated by altered transcription factor binding. Additionally, this HNF1 site replacement mutation was associated with excessive HB nucleocapsid protein expression in hepatocytes, in both in vivo and in vitro studies. This novel mutation may be specific to HBV genotype E, and its prevalence requires further investigation.

Geographic distribution, virologic and clinical characteristics of hepatitis B virus genotypes in China

The significance of hepatitis B virus (HBV) genotypes for the heterogeneity of chronic HBV infection and severity of liver disease is not well understood. The aim of this study was to determine the distribution and virologic characteristics of HBV genotypes in China and possible association with the diversity of liver disease. The study includes 1096 chronic HBV carriers from nine provinces in China. We collected clinical and laboratory data and analysed the HBV strains in sera by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and nucleotide sequencing techniques. The most common HBV genotypes were B (41%) and C (53%), while genotypes A and D were also found. A North-South divide was identified in genotype B and C distribution - genotype C was predominant in northern China, while genotype B was more prevalent in southern provinces. Patients with genotype B were younger than those with genotype C, and had a lower prevalence of HBeAg - 65%vs 72%, respectively (P = 0.03). However, the severity of liver disease did not differ significantly between patients infected with genotype B or C - neither when comparing liver function tests (1024 patients), nor hepatic inflammation and fibrosis (264 patients). Amongst 47 patients with genotype D (by PCR-RFLP), 37 (79%) were infected with a new subtype (designated Dc), having a recombination fragment from genotype C precore/core region. This is the first large-scale HBV genotype study from China and convincing documentation of the North-to-South gradient of genotypes C vs B in this country. HBV DNA recombination over the surface and precore/core genes increases the diversity of HBV strains and may have diagnostic and clinical implications.

Hepatitis B virus genotype C prevails among chronic carriers of the virus in Korea

Hepatitis B virus (HBV) is one of the major causative agents of chronic liver diseases in Korea. HBV has been classified into 8 genotypes by a divergence of >8% in the entire genomic sequence, and have distinct geographic distributions. There are limited data on the relevance between HBV genotypes and clinical outcomes in Korea. To investigate the clinical feature relating to HBV genotype in Korea, a total 120 serum samples with HBsAg (65 from Seoul and 55 from the other city in Korea) were obtained from each 30 chronic HBV carriers with asymptomatic carrier (ASC), chronic hepatitis (CH), liver cirrhosis (LC) and hepatocellular carcinoma (HCC). HBV genotype was determined by either enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies against genotype-specific epitopes in the preS2-region or the direct sequencing of small S gene. HBV genotypes were determined in 105 (87.5%) of 120 samples. HBV genotype C was identified in all HBV carriers with ASC, CH, LC, and HCC. Genotypes A, B, D, E, F and G were not detected in any of them. Genotype C HBV prevails predominantly among chronic carriers of the virus in Korea, irrespective of their clinical stages of liver disease and geographic origin.

Relationship of human leukocyte antigen class II genes with the susceptibility to hepatitis B virus infection and the response to interferon in HBV-infected patients

AIM: To study the relationship of human leukocyte antigen (HLA)-DRB1 and -DQB1 alleles with the genetic susceptibility to HBV infection and the response to interferon (IFN) in HBV-infected patients.

METHODS: Low-resolution DNA typing kit was used to determine HLA-DR-1 and -DQB1 genes in 72 patients with chronic hepatitis B (CHB) and HLA-DRB1 in 200 healthy people ready to donate their bone marrow in Shanghai. Among CHB patients, 35 were treated with IFNα -1b for 24 wk.

RESULTS: The frequencies of HLA-DRB1*06, DRB1*08 and DRB1*16 alleles in 72 patients were higher than in 200 healthy people (2.08% vs 0%, OR = 3.837, P = 0.018; 11.11% vs 5.50%, OR = 2.148, P = 0.034; and 6.94% vs 3.00%, OR = 0.625, P = 0.049, respectively); whereas that of DRB1*07 allele was lower (2.78% vs 7.75%, OR = 0.340, P = 0.046). The frequency of HLA-DRB1* 14 allele was higher in 11 responders to IFN compared with 24 non-responders (18.18% vs 2.08%, OR = 10.444, P = 0.031), whereas that of DQB1*07 allele was inverse (9.09% vs 37.50%, OR = 0.167, P = 0.021).

CONCLUSION: The polymorphism of HLA class II may influence the susceptibility to HBV infection and the response to IFN in studied CHB patients. Compared with other HLA-DRB1 alleles, HLA-DRB1*06, DRB1*08, and DRB1*16 may be associated with chronicity of HBV infection, HLA-DRB1*07 with protection against HBV infection, and HLA-DRB1*14 allele may be associated with a high rate of the response of CHB patients to IFN treatment. Compared with other HLA-DQB1 alleles, HLA-DQB1*07 may be associated with low response rate to IFN.

Relationship of genotypes of hepatitis B virus to mutations, disease progression and response to antiviral therapy

Phylogenetic analysis has led to the classification of hepatitis B virus into eight genotypes, designated A to H. The genotypes have differences in biological properties and show heterogeneity in their global distribution. These attributes of the genotypes may account not only for differences in the prevalence of hepatitis B virus mutants in various geographic regions, but also be responsible for differences in the clinical outcome and response to antiviral treatment in different population groups.

Hepatitis B virus genotypes in Korea: an endemic area of hepatitis B virus infection

OBJECTIVES

It has been reported that distribution of hepatitis B virus (HBV) genotypes shows geographic difference and are associated with clinical outcomes of HBV infection, including response to antiviral therapy and progression of chronic liver diseases. In this study, we analyzed the distribution of HBV genotypes according to the various clinical outcomes of chronic HBV infection in Korea, which is one of the most endemic areas of HBV infection.

METHODS

A total of 200 patients with chronic HBV infection were enrolled. Clinical diagnoses of the 200 patients with chronic liver diseases were as follows: hepatitis B e antigen (HBeAg)-positive healthy carrier (defined as HBeAg(+), anti-HBe(-), HBV DNA(+) by hybridization, normal transaminase; n = 40); inactive HBsAg carrier (n = 40); chronic hepatitis B (n = 40); liver cirrhosis (n = 40); hepatocellular carcinoma (n = 40). HBV genotypes were determined by nested polymerase chain reaction using genotype-specific primers.

RESULTS

All patients except 2 (inactive HBsAg carriers) were positive for nested PCR and they have genotype C regardless of clinical outcomes.

CONCLUSIONS

HBV genotype was genotype C regardless of various clinical outcomes of chronic HBV infection in Korea. Considering that HBV genotypes have clinical relevance, distribution of HBV genotype in each area should be monitored when management for chronic HBV infection is planned.

Influence of HLA-DRB1 alleles and HBV genotypes on interferon-α therapy for chronic hepatitis B

AIM: To investigate the influence of HLA-DRB₁ alleles and HBV genotypes on interferon-α therapy for chronic hepatitis B.

METHODS: HLA-DRB1*03, *07, *09, *12, *15 alleles were determined using polymerase chain reaction/sequence specific primer (PCR/SSP) technique in 126 patients with chronic hepatitis B and 76 normal control subjects in Shandong Province, and HBV genotypes were determined by nested-PCR analysis using type-specific primers in 126 patients.

RESULTS: The positivity of HLA-DRB1*07 allele in chronic hepatitis B group was significantly higher than that in normal control group (χ² = 6.33, P < 0.025, RR = 2.37). Among the 126 patients, genotype B was found in 38 (30.2%), genotype C in 69 (54.8%), and mixed genotype (B+C) in 19 (15.0%), genotypes D-F were not found. Among the 46 DRB1*07(+) patients, 7 were responders and 39 were non-responders among them (χ² = 6.71, P < 0.05). The positivity of HLA-DRB1*07 and prevalence of HBV genotype C were significantly higher in non-responders than in responders.

CONCLUSION: High positivities of HLA-DRB1 ^*07 allele and HBV genotype C are closely associated with the lower response to interferon-α therapy for chronic hepatitis B.

Significance of hepatitis B virus genotype in liver transplantation for chronic hepatitis B

Hepatitis B virus (HBV) genotype influences chronic hepatitis B disease profile but its relevance in liver transplantation (LTx) is not known. HBV genotype was identified by direct sequencing from pre-transplant sera of 119 patients who underwent LTx using lamivudine prophylaxis (genotype A,1; B,43; C,74; D,1). The baseline characteristics and outcome of 43 genotype B and 74 genotype C patients were compared. Genotype B patients had significantly more pre-transplant acute flare, worse liver functions and higher model for end-stage liver disease score. Fewer genotype B patients had HBeAg (13% vs. 32%; p=0.017), but HBV DNA seropositivity (by bDNA assay) was comparable (26% vs. 23%; p=0.727). The 3-year graft survival was 83% for genotype B and 89% for genotype C (p=0.2). The rate of HBsAg clearance or seroreversion was the same. The cumulative rate of viral breakthrough due to lamivudine-resistant mutants at 3 years was 4% for genotype B and 21% for genotype C (p=0.017). Liver biopsy after viral breakthrough showed recurrent hepatitis B in 7 of 10 genotype C patients, including 2 with fibrosing cholestatic hepatitis, and no histologic recurrence in 2 genotype B patients. In conclusion, HBV genotypes B and C are associated with different patterns of end-stage liver diseases that required transplantation, and genotype C may carry a greater risk and severity of recurrence due to lamivudine-resistant mutants.

Asian-Pacific consensus statement on the management of chronic hepatitis B: a 2005 update

BACKGROUND/AIMS

A large amount of new data on the treatment of chronic hepatitis B has become available such that the 2003 consensus statement requires revision and update.

METHODS

New data were presented, discussed and debated in an expert pre-meeting to draft a revision. The revised contents were finalized after discussion in a general meeting of APASL.

RESULTS

Conceptual background, including the efficacy and safety profile of currently available and emerging drugs, was reviewed. Nineteen recommendations were formed and unresolved issues and areas for further study were suggested.

CONCLUSION

The current therapy of chronic hepatitis B is modestly effective but not satisfactory. The development of new drugs and new strategies is required to further improve the outcomes of treatment.

Anti-HBV activity of TRL mediated by recombinant adenovirus

AIM: To investigate the inhibitive effect of hepatitis B virus (HBV)-TRL on HBV replication.

METHODS: Based on previously constructed pcDNA3.1(-)/TRL, TR, TRmut, HBV core protein (HBVc) and hEDN, interest gene sequences TRL, TR, HBVc and hEDN were inserted into adenovirus shuttle plasmid pDC316 respectively and co-transfected HEK293 cells with rescue plasmid pBHGlox(delta)E1,3Cre to acquire RAd/TRL, TR, HBVc and hEDN. And then RAds were identified, amplified and the titers in HEK293 cells were determined. RAd/TRL and TR were named as the experimental groups, and others were control ones. After HepG2.2.15 cells were infected, RAd/TRL expression was identified by indirect immunofluorescence staining. Supernatant HBV-DNA content was determined by fluorescent quantification PCR. Meanwhile, metabolism of HepG2.2.15 cells was evaluated by MTT colorimetry.

RESULTS: RAd vectors with distinct interest gene sequence were successfully constructed. Effective expression of RAd/TRL in HepG2.2.15 cells resulted in a significant decrease of supernatant HBV-DNA content compared to RAd/TR (0.63±0.14 vs 1.60±0.47, P = 0.0266, <0.05) and other control groups (0.63±0.14 vs 8.50±2.78, 8.25±2.26, 8.25±2.29, 8.50±1.51, 8.57±1.63, P<0.01). MTT assay suggested that there were no significant differences in cell metabolic activity between groups (P>0.05).

CONCLUSION: The construction and expression of RAd/TRL has been achieved and it could inhibit HBV replication successfully, which has laid the foundation for further research on anti-HBV activity in vivo.

Hepatitis B virus genotypes and hepatocellular carcinoma in Thailand

AIM

The role of hepatitis B virus (HBV) genotypes on the clinical features and prognosis of patients with hepatocellular carcinoma (HCC) is currently unknown. The aim of the present study was to evaluate the distribution of HBV genotypes and their clinical relevance in Thai patients.

METHODS

HBV genotypes were determined by PCR-RFLP in stored sera of 93 asymptomatic carriers, 103 patients with chronic hepatitis, 60 patients with cirrhosis and 76 patients with HCC. The clinical data were analyzed in relation to the HBV genotype.

RESULTS

HBV genotypes C and B were predominant in Thailand, accounting for 73% and 21%, respectively. The distributions of genotypes B and C were similar in HCC patients compared to the other groups. Genotype C was significantly more common in HCC patients who were under 40 years old than genotype B (18% vs 0%, P = 0.03), but was significantly less common in patients older than 60 years (26% vs 56.5%, P = 0.01). The positive rate of hepatitis B e antigen (HBeAg) in patients with genotype C was significantly higher than that in patients with genotype B (71.6% vs 44.4%, P = 0.03 in chronic hepatitis; 56.8% vs 11.1%, P = 0.01 in cirrhosis). There were no differences between HCC patients with genotypes B and C regarding tumor staging by CLIP criteria and the overall median survival. Multivariate analyses showed that HBV genotype was not an independent prognostic factor of survival in HCC patients.

CONCLUSION

Patients with genotype C had a higher positive rate of HBeAg and exhibited earlier progression of cirrhosis and HCC than those with genotype B. However, there were no differences in the risk of developing HCC and its prognosis between patients with these genotypes.

Distribution of hepatitis B virus genotypes in patients with chronic hepatitis B in Turkey

AIM: Hepatitis B virus (HBV) strains isolated worldwide has been classified into eight genomic groups deduced from genome comparisons and designated as genotypes A to H. We aimed to investigate prevalence of HBV genotypes and subtypes in Turkey.

METHODS: A total of 88 chronic hepatitis B (CHB) patients from 15 hospitals throughout the country were included. Patients who were HBsAg positive in serum at least for 6 mo, who had HBV-DNA in serum and elevation of ALT levels more than two times upper limit of normal, and who had percutaneous liver biopsy within 6 mo were included. Genotyping of HBV was done by restriction fragment length polymorphism (RFLP). The patients received subcutaneous 9 MU interferon-α 2a thrice a week for a period of 6 mo.

RESULTS: Genotype D was detected in 78 of 88 (88.7%) patients, however, genotyping failed in two patients (2.3%), while no product was obtained in eight (9.0%) patients. Regarding subtypes, D2 was more prevalent (67 patients between 78% and 85.9%) followed by subtype D2+deletion (seven patients of 78 or 8.9%), subtype D1 (three patients of 78% or 3.9%) and subtype D3 (one patient of 78% or 1.3%). Thirty-three patients (37.5%) were HBeAg positive compared to 55 (62.5%) anti-HBe positive patients. The endpoint for the viral response of HBeAg positive patients was 27.2%, while it was found 52.7% in HBeAg negative patients (P<0.05). Long-term persistent viral response was 29.5% for all patients.

CONCLUSION: This multi-center study indicates that the predominant genotype with CHB patients in Turkey like in other Mediterranean countries is genotype D.

Hepatitis B virus: significance of genotypes

Hepatitis B Virus (HBV) genotypes have come of age. The concept that HBV genotypes may influence the course of disease and relevant biological differences has now been recognised. However, there are still major gaps in our knowledge. Most clinical data come from Asia and describe findings in patients infected with genotypes B and C. Large scale studies with genotypes A and D as found in Europe or A, D and E from Africa are urgently needed to broaden our understanding. Experimental data which explain in vivo findings in terms of differences in molecular biology in vitro are still in the beginning. The succeeding years will see many interesting studies which will aid our understanding of how variants and genotypes of HBV influence the spectrum of disease in people infected with HBV.

Clinical outcome and virological characteristics of hepatitis B-related acute liver failure in the United States

The role of hepatitis B virus (HBV) genotypes in the outcome of acute HBV infection is unclear. In this study, we aimed to evaluate the clinical and virological features of patients with hepatitis B-related acute liver failure (HBV-ALF) in the US. Clinical and laboratory features of consecutive patients with HBV-ALF from the US ALF Study Group were analysed. Prevalence of HBV genotypes, precore stop (G1896A) and core promoter dual (T1762A, A1764T) variants among patients with HBV-ALF were compared with a cohort of 530 patients with chronic HBV infection. Thirty-four HBV-ALF patients were studied: mean age 41 years, 56% men, 25 had detectable HBV-DNA. HBV genotypes A, B, C and D were found in 36, 24, 8 and 32% patients, respectively. Precore stop and core promoter dual variants were detected in 32 and 44% of patients, respectively. Twenty-three (68%) patients survived: 14 after liver transplant, nine without transplant. Older age was the only independent factor associated with poor outcome. Compared with patients with chronic HBV infection, patients with ALF were more likely to be non-Asians (88% vs 44%, P = 0.005) and to have genotype D (32% vs 10%, P < 0.01). A higher prevalence of HBV genotype D persisted even after matching for race and HBeAg status (32% vs 16%, P = 0.007). We concluded that HBV genotype D was more frequently found in patients with HBV-ALF than those with chronic HBV infection in the US. Further studies are needed to determine if HBV genotypes play a role in the outcome of acute HBV infection.

Hepatitis B virus genotype and DNA level and hepatocellular carcinoma: a prospective study in men

BACKGROUND

Although chronic infection with hepatitis B virus (HBV) has been established as a cause of hepatocellular carcinoma (HCC), the roles of viral load and HBV genotype remain unclear.

METHODS

From 1988 through 1992, baseline blood samples were collected from 4841 Taiwanese men who were HBV carriers but had not been diagnosed with HCC. We used real-time polymerase chain reaction assays of plasma DNA samples to quantify HBV DNA levels (a measure of viral load) and determine HBV genotypes for 154 case patients who were diagnosed with HCC during 14 years of follow-up and 316 control subjects. Unconditional logistic regression was used to assess odds ratios (ORs) of HCC for HBV-related factors. All statistical tests were two-sided.

RESULTS

The risk of HCC increased with increasing HBV viral load (adjusted OR for the highest versus the lowest quintile of HBV DNA copies/mL = 7.26, 95% confidence interval [CI] = 3.54 to 14.89; P(trend)<.001). Genotype C HBV was associated with an increased risk of HCC compared with other HBV genotypes (adjusted OR = 5.11, 95% CI = 3.20 to 8.18). Both viral load and genotype were positively associated with HCC within 10-year age categories among subjects aged 30 years old to older than 60 years. Genotype C HBV was associated with increased viral load, and associations of HBV genotype and viral load with HCC risk were additive. The adjusted OR of HCC for those carrying genotype C HBV and with viral load in the highest quintile was 26.49 (95% CI = 10.41 to 67.42) compared with HBV carriers with other HBV genotypes and viral load in the lowest two quintiles.

CONCLUSIONS

Measurements of HBV viral load and genotype may help to define which male HBV carriers aged 30 years or older are at high risk for HCC.

Advances in Molecular Diagnosis of HBV Infection and Drug Resistance

Serological markers are key elements in diagnosing acute hepatitis B virus (HBV) infection and determining its possible evolution towards chronicity. Once treatment of chronic HBV is initiated with approved anti-hepadnaviral agents, such as lamivudine, interferon-alpha, or adefovir dipivoxil, the measurement of HBV DNA in serum can not only help monitor treatment efficacy but also indicates breakthrough infection should drug resistance emerge. Advances in the molecular diagnosis of drug resistance using highly sensitive methodologies such as DNA hybridization assays can further pinpoint the type of mutation responsible and, more importantly, detect upcoming viral resistance at an early stage when the variant represents only a minor fraction of the total viral population. Such new tools are especially relevant for patients at high risk for disease progression or acute exacerbation. Recent diagnostic developments including HBV genotyping and precore/core promoter assays that could well play important future roles in HBV patient management are also reviewed.

Classifying hepatitis B virus genotypes

In 1988, hepatitis B virus (HBV) was classified into four genotypes by a sequence divergence in the entire genome exceeding 8%, and designated by capital letters of the alphabet from A to D. There are seven genotypes of HBV (A-G) at present, and an eighth is on the horizon. They have an uneven geographical distribution, and only a few of them are prevalent in a given area of the world. Thus genotype A is frequent in northwest Europe, Sub-Saharan Africa, India and the North, Central and South America, B as well as C are common in Southeast Asia and Oceania, and D is prevalent in the Mediterranean area, Central Asia and South America. Genotype E is restricted to West Africa, and F is localized in Central and South America. The distribution of genotype G added to the alphabet list very recently has yet to be determined. Coinfection with HBV of distinct genotypes is not infrequent and found in about 10% of infected individuals, and is responsible for intertypic recombination of HBV genomes. The mutation for a stop codon in the precore region (G1896A) for aborting the translation of hepatitis B e antigen (HBeAg) is prohibited in HBV genomes of genotype A, as well as some of genotypes C and F, because they possess C at position 1858 that makes a Watson-Crick pair with G at position 1896. Hence, seroconversion to antibody to HBeAg is forbidden or delayed in individuals who carry them. Evidence is accumulating as regards the influence of HBV genotypes on the progression of chronic hepatitis B and response to antiviral therapies. HBV isolates even of the same genotype can differ in virological and clinical characteristics, and therefore, the genotype needs to be classified further into subtypes, especially if they are clinically relevant.

Subclones of drug-resistant hepatitis B virus mutants and the outcome of breakthrough hepatitis in patients treated with lamivudine

Breakthroughs during lamivudine therapy were assessed according to hepatitis flares and mutational polymorphism of hepatitis B virus (HBV) infecting patients. Of 42 patients with chronic hepatitis B and positive for hepatitis B e antigen in serum, 13 (30%) harbored HBV mutants with lamivudine resistance after a mean duration of 29 months on lamivudine. The virological breakthrough occurred 14.5 months after the start of lamivudine treatment, and all the patients with it developed breakthrough hepatitis 3 months later. The clinical course of breakthrough hepatitis was self-limited except in one patient who had already developed cirrhosis at the baseline. One year after breakthrough hepatitis, serum ALT, albumin, prothrombin time and platelet counts were maintained well on conventional treatments without resorting to interferon. Major HBV mutants during breakthrough hepatitis were those with M552I in the YMDD motif of viral DNA polymerase/reverse transcriptase in 7 patients (54%), M552I/L528M in 4 patients (31%) and M552V/L528M in 2 patients (15%). There were no patients in whom mutations at nucleotide 529 occurred including the 2 who later developed hepatocellular carcinoma. There was no clear relationship between distinct mutational patterns and clinical courses. Further studies are needed for making out the effects of lamivudine-resistant mutants on clinical outcomes, taking into considerations genotypes of HBV.

Hepatitis B virus genotypes and hepatocellular carcinoma in Taiwan

With phylogenetic analysis of hepatitis B virus (HBV) isolates, eight different genotypes (A to H) have been recognized worldwide. The impact of HBV genotypes on the clinical aspects of HBV infection in Taiwan, including the clinical outcome of chronic infection and therapeutic response to antiviral treatments, has been clarified. Our data showed that genotypes B and C are the predominant HBV strains in Taiwan, and genotype C is associated with more severe liver disease including cirrhosis and hepatocellular carcinoma (HCC), whereas genotype B is associated with the development of HCC in young noncirrhotic patients. Serologically, genotype C tends to have a higher frequency of hepatitis B e antigen (HBeAg) positivity and a higher serum HBV DNA level than genotype B. In addition, genotype C patients, compared to genotype B patients, have a delayed HBeAg seroconversion in the immune clearance phase of chronic HBV infection. Virologically, genotype C bears a higher frequency of basal core promoter mutation than genotype B. Our recent data further indicated that patients with basal core promoter mutation are significantly more associated with the development of HCC than those without, which applies to both genotypes B and C. In addition, the prevalence of basal core promoter mutation in young HCC patients is comparable to older HCC patients but is significantly higher than that in age-matched inactive carriers, irrespective of genotypes. Although superinfection of HBV on hepatitis B carriers indeed occurs in Taiwan, it is rarely associated with acute exacerbations. As to the response to antiviral treatments, genotype C is associated with a lower response rate to interferon therapy compared to genotype B. In addition, genotype B seems to have a better virological response to lamivudine as compared to genotype C, but both genotypes have a similar risk in the development of lamivudine resistance. These lines of evidence highlight the remarkable differences in the clinical and virological characteristics between Taiwanese patients infected with different genotypes. In conclusion, pathogenic and therapeutic differences do exist among HBV genotypes in Taiwan, and determining the genotype in patients with chronic HBV infection would help gain further information in anthropologic, clinical, virological and prognostic investigations.

Hepatitis B virus genotypes and hepatocellular carcinoma in Japan

Hepatitis B virus (HBV) is one of the major causative agents of hepatocellular carcinoma (HCC) in Southeast Asia where HBV genotype B (HBV/B) and genotype C (HBV/C) are prevalent. Clinical and virological differences were evaluated between HCC patients in Japan and Taiwan, all of whom were infected with HBV/B and HBV/C. In Japan, the prevalence rates of HBV/B and HBV/C were 12 and 85%, respectively, in patients with chronic HBV infection, which is similar to those of 13 and 86% in patients with HCC. In the HCC patients with HBV/B, the mean age was 70 years and higher than that of 55 years in those with HBV/C. In Taiwan, however, HBV/B was detected in 61% and HBV/C in 31% of patients with HCC. Furthermore, the mean age of HCC patients with HBV/B in Taiwan was 50 years and younger compared to the 59 years of those with HBV/C. These differences may be explained by a distinct distribution of subtypes of HBV/B between the two countries. In Taiwan as well as in most Asian countries only the subtype Ba of HBV/B is found, while the majority of Japanese patients with HBV/B have the subtype Bj. Although the risk factors associated with HCC should be investigated with respect to host and environmental factors, the differences in genotypes and subtypes of HBV would need to be taken into consideration in etiological and clinical studies on HCC.

Hepatitis B virus genotype has no impact on hepatitis B e antigen seroconversion after lamivudine treatment

AIM: To investigate the association of hepatitis B virus (HBV) genotype and HBeAg seroconversion after nucleotide analogue treatment.

METHODS: Chronic hepatitis B patients receiving lamivudine followed up for at least 6 months post-treatment were studied. Consecutive treatment-naïve patients who were prospectively followed up in the clinic for at least 18 months were studied as controls. HBeAg seroconversion was defined as loss of HBeAg, appearance of anti-HBe and normalization of alanine aminotransferase for at least 6 months.

RESULTS: Thirty-five patients on lamivudine and 96 control patients followed up for 39 (18-49) months were studied. Lamivudine was given for 12 (10-18) months, and patients were followed up for 15 (6-34) months after drug cessation. Genotype B and C HBV were found in 43 and 88 patients and HBeAg seroconversion occurred in 12 (28%) and 16 (18%) patients, respectively (P = 0.30). There was no difference in HBeAg seroconversion between patients infected by genotype B and C HBV in the control (35% vs 21%, P = 0.25) and lamivudine-treated (14% vs 10%, P = 1.00) groups.

CONCLUSION: HBeAg seroconversion after treatment by lamivudine was not influenced by the HBV genotype.

Rapid and sensitive assays for determination of hepatitis B virus (HBV) genotypes and detection of HBV precore and core promoter variants

Hepatitis B virus (HBV) genotypes may influence HBeAg seroconversion rates, mutational patterns in the precore (PC) and core promoter (CP) regions, severity of liver disease, and response to antiviral treatment. Development of rapid, simple, and standardized assays to detect viral genotypes and common mutations in the PC and CP regions can accelerate research on the clinical significance of these variants. We aim to assess the accuracy of a line probe assay in determining HBV genotypes and detecting HBV PC and CP variants. HBV genotypes in 701 patients and PC and CP variants in 600 patients with chronic HBV infection from China and the United States were studied using the INNO-LiPA assay. All but one (99.9%) sample were classified by the genotyping assay. All eight genotypes, i.e., A to H, were found. The INNO-LiPA genotyping assay results were completely concordant with those of sequencing. Using the INNO-LiPA PC assay, 99.8 and 94.7% samples were classifiable in the PC and CP regions, respectively. The PC assay results were completely concordant with those of sequencing in all samples that showed either wild-type or variant sequence. The line probe assay was more sensitive in detecting mixtures than was direct sequencing. By INNO-LiPA, only 50 and 27% of the samples, with mixed wild-type and variant sequence in the PC and CP region, respectively, showed mixed sequence by direct sequencing. INNO-LiPA is rapid, sensitive, and reliable-thus enabling accurate determination of HBV genotypes and detection of PC and CP variants in a large population of patients.

Inhibition of HBV targeted ribonuclease enhanced by introduction of linker

AIM: To construct human eosinophil-derived neurotoxin(hEDN) and HBV core protein (HBVc) eukaryotic fusion expression vector with a linker (Gly₄Ser)₃ between them to optimize the molecule folding, which will be used to inhibit HBV replication in vitro.

METHODS: Previously constructed pcDNA3.1(-)/TR was used as a template. Linker sequence was synthesized and annealed to form dslinker, and cloned into pcDNA3.1(-)/TR to produce plasmid pcDNA3.1(-)/HBc-linker. Then the hEDN fragment was PCR amplified and inserted into pcDNA3.1(-)/HBc-linker to form pcDNA3.1(-)/TNL in which the effector molecule and the target molecule were separated by a linker sequence. pcDNA3.1(-)/TNL expression was identified by indirect immunofluorescence staining. Radioimmunoassay was used to analyse anti-HBV activity of pcDNA3.1(-)/TNL. Meanwhile, metabolism of cells was evaluated by MTT colorimetry.

RESULTS: hEDN and HBVc eukaryotic fusion expression vector with a linker (Gly4Ser)3 between them was successfully constructed. pcDNA3.1(-)/TNL was expressed in HepG2.2.15 cells efficiently. A significant decrease of HBsAg concentration from pcDNA3.1(-)/TNL transfectant was observed compared to pcDNA3.1(-)/TR (P = 0.036, P < 0.05). MTT assay suggested that there were no significant differences between groups (P = 0.08, P > 0.05).

CONCLUSION: Linker introduction enhances the inhibitory effect of HBV targeted ribonuclease significantly.