Mutations of the core promoter and response to interferon treatment in chronic replicative hepatitis B

Genetic characteristics of hepatitis B virus genotypes as a factor for interferon-induced HBeAg clearance

The factors determining the responsiveness of different hepatitis B virus (HBV) genotypes to interferon treatment are not fully understood. We investigated the relationship between HBV genetic characteristics and the outcome of short (16 weeks) or prolonged (32 weeks) treatment with standard interferon-alpha in a prospectively followed cohort of 103 patients across Europe with HBeAg positive chronic hepatitis B. INNO-LiPA assays and HBV DNA sequencing were used to determine HBV genotypes, mutations in the core promoter and precore/core regions. After 16-weeks interferon-alpha treatment, the rate of HBeAg clearance was higher in genotype A versus all other genotypes (P = 0.014), or genotype D alone (P = 0.05). The HBV genome analysis revealed that: (i) after 16-weeks treatment, an HBV subpopulation with core promoter mutations emerged or increased (P < 0.001) only in genotype A; (ii) the core gene of genotype A has the lowest number of amino acid variations in comparison with genotypes B, C, or D. Logistic regression analysis identified genotype A as a positive predictor of short (16 weeks) treatment response (P = 0.001; odds ratio 6.19, 95 confidence interval 1.94-19.8), having a greater impact than baseline HBV DNA or alanine aminotransferase (ALT) levels. In contrast, the response to prolonged interferon-alpha treatment was not different between HBV genotypes. These results suggest that HBV genotype A responds earlier to interferon treatment than other genotypes, which is associated with its molecular characteristics. The optimal duration of interferon-based therapies in chronic hepatitis B may vary between different HBV genotypes.

Interferon and lamivudine monotherapy on chronic hepatitis B in Japan

AIM

We show data of interferon (IFN) and lamivudine monotherapy on chronic hepatitis B in Japan.

METHODS

Data collected from sixty-six chronic hepatitis B (CHB) Japanese patients who were treated with IFN for 6 months were analyzed. The efficacy of long-term IFN therapy in 52 patients with e-antigen positive CHB, and data from 290 chronically HBV-infected patients who were treated with lamivudine for more than 3 years, were analyzed.

RESULTS

Six-month IFN therapy: among 45 patients with HBeAg at commencement of IFN therapy, nine (20%) were responders. Young patients especially those with high serum alanine aminotransferase (ALT) levels were much more likely to respond to IFN therapy. Twelve-month IFN therapy: theresponse rate was 31% among 52 patients with HBeAg. Long-term lamivudine therapy: YMDD motif mutation was detected in 167 of 290 patients (58%) during lamivudine treatment. Breakthrough hepatitis from lamivudine resistant virus was detected in 93 of 290 patients (32%). Finally, 813 patients were treated by lamivudine between September 1995 and February 2006. Fifteen patients lost HBsAg during and after lamivudine therapy.

CONCLUSION

Long-term interferon therapy has a better response than short-term interferon therapy. Some patients lost HBsAg during and after lamivudine therapy.

In vitro resistance to interferon-alpha of hepatitis B virus with basic core promoter double mutation

The hepatitis B virus (HBV) genome basic core promoter (BCP) modulates HBeAg secretion at the transcriptional level. In addition to pre-core mutations, variations in the BCP are related to hepatitis B e antigen (HBeAg)-negative chronic hepatitis B. HBeAg-negative chronic hepatitis B patients show a lower sustained response to interferon (IFN). The aim of this study was to determine if there is a relationship between HBV BCP mutation and sensitivity of HBV to IFN-alpha in vitro. BCP mutations were introduced by site-directed mutagenesis and the entire genomes of wild-type and mutant HBV were transiently transferred into Huh7 cells by calcium phosphate transfection. With or without IFN-alpha, viral products in the culture medium and viral replication intermediates in the cytoplasm were detected 3 days after transfection. The amount of hepatitis B surface antigen (HBsAg) secreted by wild-type HBV and the BCP mutant was similar, while HBeAg secreted by the mutant was decreased by 35.4%. HBV particles and replication intermediates of the BCP mutant were increased. After IFN-alpha was added, HBeAg, HBV DNA and HBV replication intermediates decreased for both the wild-type HBV (by 25.7%, 31.8%, 29.8%, respectively) and the BCP mutant (by 8.4%, 27.4%, 10.1%, respectively). These data indicate that HBV harboring the BCP double mutation has stronger replication competence and lower sensitivity to IFN-alpha than wild-type.

Initial load of hepatitis B virus (HBV), its changing profile, and precore/core promoter mutations correlate with the severity and outcome of acute HBV infection

BACKGROUND

The pathogenesis of the fulminant or severe form of acute hepatitis B virus (HBV) infection remains unclear, although both host- and virus-specific factors are considered to have a great impact on the c course. We aimed to define possible viral factors implicated in the severe form of acute HBV infection.

METHODS

We investigated viral factors in 42 patients with acute HBV infection: 11 had fulminant hepatitis (FH); 9 had a severe form of acute hepatitis (SAH), defined as having a prothrombin activity of less than 40% without encephalopathy; and 22 had acute self-limited hepatitis (AH).

RESULTS

Although there was no significant difference in serum HBV DNA levels on admission among the three groups, the level decreased more rapidly in patients with SAH or FH than in those with AH. In patients with SAH or FH, the HBV load on admission was higher in patients who died than in those who recovered (7.0 +/- 1.6 vs 5.6 +/- 1.0 log copies/ml; P=0.0293). In univariate analysis, seronegativity for hepatitis B envelope antigen (HBeAg) and mutations in both the precore (G1896A and/or G1899A) and core promoter (T1753A/C and/or T1754C/G and/or A1762T/G1764A) were associated with FH (odds ratio [OR], 5.60; P=0.0269 and OR, 52.0; P=0.0006; respectively). In multivariate logistic regression analysis, only the presence of precore/core promoter mutations was associated with FH (OR, 42.8; P=0.0020).

CONCLUSIONS

The rapid decrease in viral load in the early phase of acute HBV infection was associated with the severity of the disease. A high viral load on admission and the presence of both precore and core promoter mutations in patients with severe coagulopathy closely correlated with mortality.

Prevalence of hepatitis B virus genotype D in precore mutants among chronic liver disease patients from New Delhi, India

Hepatitis B is one of the most important causes of chronic viral hepatitis world wide. Mutations in the precore region of the hepatitis B virus (HBV) genome are frequently found in hepatitis B envelope antigen-negative cases. Data from India on the HBV genotype-associated distribution of precore mutations are limited. Our objective in this study was to genotype and detect the precore mutant with a point mutation from G to A at nucleotide 1896 using ligase chain reaction (LCR) and direct sequencing. A total of 115 cases of chronic liver disease were screened. The cases were evaluated on the basis of history, clinical examination, liver function profile, and serological test for HBV infection, which includes HBsAg, anti HBcIgG, HBeAg using commercially available ELISA kits. The cases, which were HBeAg+, HBeAg-, and HBV DNA+, were subjected to LCR and confirmed by direct sequencing. Of 115 chronic liver disease cases, 50 (43.5%) cases were HBV DNA positive. All cases were subjected to LCR; 11 (22%) cases confirmed the presence of precore mutants, while the remaining 39 (78%) were classified as the wild form of the virus. HBV genotyping by direct sequencing revealed that genotype D was predominant in both wild and mutant forms of the virus. We conclude that the HBV genotype distribution was not significantly different between precore mutants and the wild form of the virus (P>0.05). North Indian patients with genotype D were more likely to have persistent HBV infection with precore mutants. HBV genotypes correlate with the clinical outcome of chronic HBV infection.

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.

Expertise of laboratories in viral load quantification, genotyping, and precore mutant determination for hepatitis B virus in a multicenter study

A national evaluation study was performed in 14 specialized laboratories with the objective of assessing their capacities to provide (i) hepatitis B virus (HBV) viral loads (VL), (ii) HBV genotypes, and(iii) identification of precore/core mutants. The panel consisted of 12 HBV DNA-positive samples with VLs from 2.8 to 9.1 log(10) copies/ml, different HBV genotypes (A to F), and 3 mutant and 9 wild-type samples at nucleotide 1896. The coefficients of variation of the mean VLs ranged from 2.4% to 10.4% with the Cobas HBV Monitor assay, from 1.8% to 5.5% with the Cobas TaqMan 48, from 1.5 to 26.2% with RealArt HBV PCR, and from 0 to 7% with branched DNA (bDNA). The Cobas Monitor assay underestimated the VLs of genotype F samples, with differences ranging from 1.4 to 2.4 log(10) copies/ml. The accuracies of genotype determinations ranged from 33% to 100%, and those of precore mutant determinations ranged from 25 to 100%. This study showed some drawbacks of two widely used assays: (i) Cobas Monitor has a narrow dynamic range and underestimates genotype F sample VLs and (ii) bDNA shows poor sensitivity and may fail to identify patients with low VLs. With higher performance in terms of analytical sensitivity combined with a larger dynamic range and an ability to quantify the main genotypes equally, real-time PCR methods appear more appropriate for accurate monitoring of HBV DNA quantification. Furthermore, the clinical implications of HBV genotyping and the determination of precore/core mutants need to be clearly stated to justify the standardization of these methods.

Quantitative analysis of HBsAg, IgM anti-HBc and anti-HBc avidity in acute and chronic hepatitis B

BACKGROUND AND OBJECTIVES

We evaluated hepatitis B virus (HBV) serological markers by novel, quantitative immunoassays in order to study their behaviours and possible role in the various phases of HBV infection.

STUDY DESIGN

The quantitative determination of HBsAg and anti-HBc/IgM by chemiluminescent immunoassays (Abbott Architect) and the calculation of anti-HBc avidity index have been carried out on repository specimens from patients with acute or chronic hepatitis B.

RESULTS

In acute hepatitis the levels of HBsAg were generally >10,000 UI/mL and decreased sharply in the recovery phase. In 35 anti-HBe-positive chronic hepatitis cases HBsAg levels were generally lower than 10,000 UI/mL (mean: 2655), whereas in five HBeAg-positive chronic hepatitis patients the mean value was 78,756 UI/mL and 90% of specimens exceeded 10,000 UI/mL. The lowest values (mean: 1029 IU/mL) were found in the seven patients with minimal hepatic damage. IgM anti-HBc antibodies were positive in all acute cases and in 68/207 samples (32.85%) from patients with chronic hepatitis, with significantly lower levels (average sample/cutoff (S/CO) ratio: 2.95 in chronic cases versus 25.96 in acute cases; p<0.005). A S/CO value of 10 for anti-HBc IgM had a 100% negative predictive value and a 99.13% positive predictive value for acute hepatitis B. The study of anti-HBc avidity by an experimental procedure showed that an avidity index (AI) threshold of 0.7 had a good efficacy to discriminate the cases of chronic hepatitis, among whom only 2 specimens out of 193 (1.04%) had an AI<0.7.

CONCLUSION

The quantitative determination of HBsAg, anti-HBc/IgM and anti-HBc avidity provides additional information and may be useful in the differential diagnosis of acute and chronic HBV infections and in the follow-up of chronically infected patients.

Genetic variability in the precore and core promoter regions of hepatitis B virus strains in Karachi

Background

Hepatitis B virus (HBV) genotypes have distinct geographic distribution. Moreover, much genetic variability has been described in the precore (PC) and basal core promoter (BCP) regions of the HBV genome. The local prevalence of HBV genotypes and mutations has not been well studied. The aim of the present study is to determine the prevalence of HBV genotypes and mutations in the PC and BCP region in HBV strains in Karachi.

Methods

A total of 109 chronic hepatitis B patients with detectable HBV DNA by a PCR assay were enrolled in the study. Sera were tested for HBeAg, anti-HBe antibody and liver profile. HBV genotypes and mutations in the PC and BCP regions were detected by INNO-LiPA line-probe assays.

Results

Of the 109 patients investigated, 38 (35%) were HBeAg positive while 71 (65%) were HBeAg negative. Genotype D was present in 100% of the patients. Two patients had co-infection with genotype A. There was no significant difference in the baseline characteristics, mean ALT levels, and presence of clinical cirrhosis in patients with HBeAg positive or negative strains with or without PC and BCP mutations. Of the 38 HBeAg positive patients, 9 (24%) had PC and BCP mutations. In the HBeAg negative patient group, mutations were detected in 44 (62%) of the strains investigated. More than one mutation was common, seen in 26 (37%) patients with HBeAg negative disease and 6 (16%) patients with HBeAg positive disease. Twelve (17%) HBeAg negative patients had dual T1762 and A1764 mutations. None of the HBeAg positive patients had T1762 mutation. Mutations were undetectable in 27 (38%) of patients with HBeAg negative disease.

Conclusion

Our study shows that type D is the main HBV genotype in Karachi, Pakistan. Significant numbers of patients infected with this genotype have PC and BCP variants. Mutations at more than one site are common. Patients harboring these mutants do not differ significantly in their clinical presentation from patients having wild type infection.

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.

Variant of hepatitis B virus with primary resistance to adefovir

The reverse-transcriptase inhibitor lamivudine (Zeffix, GlaxoSmithKline) is often used to treat chronic infection with hepatitis B virus (HBV) until resistance develops. Treatment may then be switched to the reverse-transcriptase inhibitor adefovir (Hepsera, Gilead), which has a lower frequency of resistance. Here, we describe three cases of primary adefovir resistance that were sensitive to tenofovir (Viread, Gilead). All three cases involved a rare HBV variant with a valine at position 233 of the reverse-transcriptase domain instead of isoleucine (rtI233V), as in the wild-type virus. This HBV variant also displayed resistance to adefovir and sensitivity to tenofovir in vitro.

Therapy of hepatitis B -- viral suppression or eradication?

The practicing clinician is currently faced with a number of treatment options for chronic hepatitis B. Beginning in 1998 with the licensing of lamivudine and subsequently adefovir, the treatment paradigm shifted from 4 to 6 months of conventional alfa interferon to a year of nucleoside analog therapy. However, prolonged treatment with nucleoside analogs is often needed to optimize virological response. Recently, a 48-week regimen of pegylated interferon for hepatitis B e antigen (HBeAg)-positive and HBeAg-negative chronic hepatitis B has been shown to be effective, and long-term nucleoside analog therapy has been demonstrated to maintain viral suppression. These findings have added to the complexity of decision-making and have raised questions about whether a finite course of pegylated interferon or nucleoside analog therapy, with possible long-term maintenance, is better as first-line therapy. Each of these fundamentally different approaches has advantages and limitations, and both have a place in the therapeutic armamentarium against chronic hepatitis B. Long-term therapy with nucleoside analogs, however, raises a number of practical concerns that have not been fully addressed as of yet. I will present evidence in support of the recommendation that antiviral therapy should ideally be directed toward achieving the highest rate of viral clearance with the shortest interval of treatment.

Treatment with Peg-interferon alpha-2b for HBeAg-positive chronic hepatitis B: HBsAg loss is associated with HBV genotype

BACKGROUND AND AIMS

Hepatitis B surface antigen (HBsAg) loss is the hallmark of a complete response to antiviral therapy for chronic hepatitis B. In this study, we investigated the frequency of HBsAg loss after treatment with pegylated (Peg)-interferon alpha-2b.

METHODS

In a multicenter randomized controlled trial, 266 HBeAg-positive patients were treated for 52 wks with Peg-interferon alpha-2b (100 microg/wk) in combination with either lamivudine (100 mg/day) or placebo. Posttreatment follow-up was 26 wks.

RESULTS

At the end of follow-up, 95 (36%) of the 266 patients exhibited HBeAg loss, 18 (7%) HBsAg loss, and 16 (6%) HBsAg seroconversion. Addition of lamivudine did not enhance HBeAg loss, HBsAg loss, or development of anti-HBs. All 18 patients who showed HBsAg loss had normal ALT; 11 (61%) of these patients were also hepatitis B virus (HBV) DNA negative (<400 copies/mL) at the end of follow-up. Loss of HBsAg differed according to HBV genotype: 14% for genotype A, 9% for genotype B, 3% for genotype C, and 2% for genotype D (A vs D: p = 0.006).

CONCLUSIONS

One year of Peg-interferon alpha-2b for HBeAg-positive patients led to HBsAg loss in 7%. Our study indicates that treatment with Peg-interferon alpha-2b is the best therapy to achieve HBsAg clearance in patients with genotype A.

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.

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.

Hepatitis B virus genome variability and disease progression: the impact of pre-core mutants and HBV genotypes

The hepatitis B virus (HBV), a member of the Hepadnaviridae family, is prone to mutations due to its asymmetric replication via reverse transcription of an RNA intermediate. The estimated mutation rate of the hepadnavirus genome is 2 x 10(4) base substitutions/site/year. This mutation rate is approximately 100 times higher than that of other DNA viruses but between 100 and 1000 times lower than that of RNA viruses. Analyses of both naturally occurring viral variants and in vitro mutagenesis studies have identified some mutations that have a role in viral latency, pathogenesis of liver disease, immune escape, and resistance to antiviral therapy.

High rates of early HBeAg seroconversion and relapse in Indian patients of chronic hepatitis B treated with Lamivudine: results of an open labeled trial

Background

The use of Lamivudine in chronic hepatitis B (CHB) is well known, however the reported rate of HBeAg sero-conversion and its durability post-treatment have varied considerably. We undertook the present study to study the effect of Lamivudine on HBeAg loss and seroconversion rates in Indian patients of CHB in relation to frequency, predictors and durability.

Methods

We treated 60 patients of e antigen positive CHB (with active viral replication and ongoing necro-inflammatory activity) with Lamivudine. They were followed up by monthly aminotransferases, and 3 monthly HBeAg and anti-HBe. Those who attained HBeAg sero-conversion were advised to discontinue Lamivudine after 6 months and followed up every 3 months thereafter, to see for relapse. Treatment was given for maximum of 3 years if not sero-converted.

Results

The annual incremental loss of HBeAg in patients receiving Lamivudine was 25 (41.6%) at end of 1^st year, 33 (55%) at 2^nd year and 35 (58.3%) at 3^rd year. The corresponding rates for full sero-conversion were 17/60 (28.6%), 22/60 (36.6%) and 24/60 (40%) in the 3 years. HBeAg loss correlated with increased pre-therapy ALT levels (p = 0.002) and decreased pretreatment HBV-DNA levels (p = 0.004). The presence of cirrhosis had no influence on the rate of HBeAg loss. Relapse occurred in 35% (7/20) post-treatment at median time of 6 months.

Conclusion

Indian patients showed a higher rate of HBeAg sero-conversion in the first year of Lamivudine treatment. This correlated with baseline ALT and inversely with HBV-DNA levels. Relapse rate after treatment was high and occurred soon after stopping treatment.

T1764G1766 core promoter double mutants are restricted to Hepatitis B virus strains with an A1757 and are common in genotype D

To investigate the role of pre-core and basal core promoter (BCP) mutants in hepatitis B e antigen (HBeAg)-negative chronic hepatitis B (e-CHB) in Iran, Hepatitis B virus strains from 30 patients and 42 anti-HBe-positive asymptomatic carriers (ASCs) were characterized. G1896A pre-core stop mutants, detected in 77 % of e-CHB patients and 85 % of ASCs, showed no association with virus load or aminotransferase levels. Twenty per cent of e-CHB patients and 31 % of ASCs harboured T1762A1764 mutants. When this double mutation was associated with G1757, it was linked to a higher virus load in patients than when it was associated with A1757 (10(5.2+/-1.8) vs 10(3.2+/-0.8) copies ml(-1); P=0.004). Interestingly, the most common BCP mutations were T1764 and G1766, which were present in 33 % of e-CHB patients and 29 % of ASCs. These were associated with higher virus load and aminotransferase levels compared with patients lacking core promoter mutations, although this was not significant. The T1764G1766 double mutation was only present in strains with A1757 (P<0.001), which is more frequent in strains of genotype D than in those belonging to other genotypes. On the other hand, the T1762A1764 double mutation was found more frequently in association with G1757 than with A1757. The T1762A1764 double mutation forms a binding site for hepatocyte nuclear factor 1 (HNF1), which is constrained by A1757. However, the T1764G1766 double mutant may form a binding site for HNF3. Thus, position 1757 affects the emergence of promoter double mutants and would predict a relative genotypic restriction of both the T1762A1764 and the T1764G1766 double mutants.

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.

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.

Chronic Hepatitis B and Viral Genotype: The Clinical Significance of Determining HBV Genotypes

The global health challenge posed by the hepatitis B virus (HBV) centres around the widespread distribution and the serious complications as a result of persistent infection with the virus. As with other chronic diseases mediated by pathogens such as human immunodeficiency virus (HIV) and hepatitis C virus (HCV), clinicians are searching for epidemiological, pathological and viral characteristics of HBV infection that may lead to more effective management of patients with chronic infection. Unlike HCV, the role of HBV genotype in disease progression, severity, response to therapy and drug resistance is still under investigation and just beginning to be clarified. This review examines the potential role of HBV genotype determination in the clinic with emphasis on how this genetic information may used to provide effective management for the treatment of patients with chronic hepatitis B.

An application of gene comparative image for predicting the effect on replication ratio by HBV virus gene missense mutation

Hepatitis B viruses (HBVs) show instantaneous and high-ratio mutations when they are replicated, some sorts of which significantly affect the efficiency of virus replication through enhancing or depressing the viral replication, while others have no influence at all. The mechanism of gene expression is closely correlated with its gene sequence. With the rapid increase in the number of newly found sequences entering into data banks, it is highly desirable to develop an automated method for simulating the gene regulating function. The establishment of such a predictor will no doubt expedite the process of prioritizing genes and proteins identified by genomics efforts as potential molecular targets for drug design. Based on the power of cellular automata (CA) in treating complex systems with simple rules, a novel method to present HBV gene image has been introduced. The results show that the images thus obtained can very efficiently simulate the effects of the gene missense mutation on the virus replication. It is anticipated that CA may also serve as a useful vehicle for many other studies on complicated biological systems.

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.

Three-phase sequential combined treatment with lamivudine and interferon in young patients with chronic hepatitis B

Alpha-interferon (IFN) or lamivudine monotherapy are ineffective in treating chronic HBeAg positive patients with high viral load and low alanine aminotransferase (ALT) levels. We investigated whether priming lamivudine treatment might enhance the antiviral and immunostimulant action of lamivudine/IFN combination in young tolerant patients. Eleven chronic HBeAg positive patients received: 100 mg/day lamivudine for 3 months followed by IFN 5 MU/m2/tiw with lamivudine 100 mg/day for 6 months and then lamivudine alone 100 mg/day for 9 months. Quantitative hepatitis B virus (HBV)-DNA was evaluated during treatment and core-promoter, precore and polymerase HBV mutants were detected by direct sequencing at the end of therapy. Serum HBV-DNA levels dropped during lamivudine monotherapy and in combination with IFN. After IFN withdrawal, viraemia transiently increased to high levels in five of 11 (45%) patients who showed rt M204V/I lamivudine mutant resistant. Two patients cleared HBeAg without anti-HBe seroconversion. One patient presented core-promoter (A1762T/G1764A) and precore stop codon mutations. Hence, three-phase sequential combined lamivudine/IFN treatment reduced HBV-DNA serum level, but did not lead to HBeAg and HBV-DNA clearance in these highly viraemic, normal ALT patients. Lamivudine/IFN combination did not prevent the emergence of YMDD lamivudine resistance. New schedules of antiviral treatments must be evaluated in this population at risk of disease progression.

Emerging treatments in chronic hepatitis B

Although the management of chronic hepatitis B has improved over the last decade, none of the available therapeutic agents, IFN-alpha, lamivudine and adefovir dipivoxil, can achieve sustained off-therapy responses in most cases. Therefore, several newer, mainly antiviral and immunomodulatory agents, are being evaluated. Pegylated IFN-alpha(2a) has been shown to be more effective than lamivudine or standard IFN-alpha monotherapy in achieving post-therapy biochemical and virological responses, and is expected to be licensed soon for the treatment of chronic hepatitis B. Newer antiviral agents, such as entecavir and telbivudine, appear to be quite effective initially, but their sustained off-therapy response rates remain unknown. The preliminary data of monotherapies with immunomodulatory agents, or of combination therapies, have been rather disappointing. Long-term maintenance treatment with antiviral agent(s) with good safety and tolerability profiles and low resistance rates appears to be the most realistic future therapeutic option for most chronic hepatitis B patients.

Effect of mutating the two cysteines required for HBe antigenicity on hepatitis B virus DNA replication and virion secretion

Hepatitis B virus (HBV) variants with impaired expression of e antigen (HBeAg) frequently arise at the chronic stage of infection, as exemplified by precore and core promoter mutants. Since an intramolecular disulfide bond maintains the secondary structure of HBeAg, we explored effect of missense mutations of either cysteine codon. Consistent with earlier reports, substitution of each cysteine rendered HBeAg nearly undetectable. With underlying nucleotide changes at the loop of pregenome encapsidation signal, the C-7 mutants were severely impaired in pregenomic RNA packaging and hence DNA replication. Although none of the missense mutations at C61 reduced DNA replication, replacement with arginine, but not alanine, aspartic acid, phenylalanine, or serine, blocked virion secretion. Consistent with the detection of C61R genome from a patient serum, secretion block of the C61R mutant could be overcome by co-expression of wild-type core protein. In conclusion, point mutations of the C61 codon may generate viable HBeAg-negative variants.

Pegylated interferon alfa-2b alone or in combination with lamivudine for HBeAg-positive chronic hepatitis B: a randomised trial

BACKGROUND

Treatment of HBeAg-positive patients with chronic hepatitis B is not effective in most. A combination of immunomodulatory pegylated interferon alfa-2b and antiviral lamivudine might improve the rate of sustained response.

METHODS

307 HBeAg-positive patients with chronic hepatitis B were assigned combination therapy (100 microg/week pegylated interferon alfa-2b and 100 mg/day lamivudine) or monotherapy (100 microg/week pegylated interferon alfa-2b and placebo) for 52 weeks. During weeks 32-52 the pegylated interferon dose was 50 microg/week in both treatment groups. The analyses were based on the modified intention-to-treat population after exclusion of 24 patients from one centre withdrawn for misconduct, ten who lost HBeAg before the study start, and seven who received no study medication. All included patients were followed up for 26 weeks after treatment.

FINDINGS

49 (36%) of 136 patients assigned monotherapy and 46 (35%) of 130 assigned combination therapy had lost HBeAg at the end of follow-up (p=0.91). More of the combination-therapy than of the monotherapy group had cleared HBeAg at the end of treatment (57 [44%] vs 40 [29%]; p=0.01) but relapsed during follow-up. Patterns were similar when response was assessed by suppression of serum hepatitis B virus (HBV) DNA or change in concentrations of alanine aminotransferase. Response rates (HBeAg loss) varied by HBV genotype (p=0.01): A, 42 (47%) patients; B, ten (44%); C, 11 (28%); and D, 26 (25%).

INTERPRETATION

Treatment with pegylated interferon alfa-2b is effective for HBeAg-positive chronic hepatitis B. Combination with lamivudine in the regimen used is not superior to monotherapy. HBV genotype is an important predictor of response to treatment.

Molecular virology in chronic hepatitis B: genotypes

Different hepatitis B virus genotypes have different geographical distributions, natural disease progression, risk of hepatocellular carcinoma and treatment responses. This article summarizes the recent literature in this area.

Current therapies for chronic hepatitis B virus infection

Patients who are chronically infected with the hepatitis B virus are at an increased risk of developing cirrhosis, hepatic decompensation and hepatocellular carcinoma. Therapeutic intervention offers the only means of interrupting this progression. Currently there are three licensed agents for the treatment of chronic hepatitis B virus infection. These are interferon-alpha, an immunomodulator, and two synthetic nucleos(t)ide analogs, namely lamivudine (Epivir, GlaxoSmithKline) and adefovir dipivoxil (Hepsera, Gilead Sciences). This review aims to summarize current experience with these drugs in the treatment and management of patients with chronic hepatitis B virus infection, their efficacy, and current problems of drug resistance. An outline of future treatment perspectives is also included.

Quantification and genotyping of hepatitis B virus in a single reaction by real-time PCR and melting curve analysis

BACKGROUND/AIMS

Both viral titer and genotype of hepatitis B virus (HBV) play critical roles in determining clinical outcome and response to antiviral treatment in hepatitis B patients. In this study, a method was developed to determine both parameters in a single-tube reaction.

METHODS

The method contains two consecutive steps, the first step used real-time PCR for quantification and second step used melting curve analysis for genotyping. For accurate quantification, the PCR primers and hybridization probes were selected from highly conserved regions to ensure the equivalent amplification and hybridization of all genotypes of HBVs. Within the sensor probe there exists signature single nucleotide polymorphisms (SNPs), which could effectively differentiate different HBV genotypes by showing different melting temperatures.

RESULTS

The quantification results showed great consistency with the commercial assays in linear range from 10(2) to 10(11) copies/ml. By comparison with the traditional restriction fragment length polymorphism (RFLP) methods, 99% of samples were accurately genotyped by current assay, and with a higher detection rate. In addition, this method can detect mixed HBV infections.

CONCLUSIONS

Currently, this methodology can be applied to areas prevalent with HBV genotypes B and C, providing an efficient alternative for clinical diagnosis and large-scaled longitudinal studies.

Basal core promoter and precore mutations in the hepatitis B virus genome enhance replication efficacy of Lamivudine-resistant mutants

During chronic hepatitis B virus (HBV) infection, mutations in the precore (PC) or basal core promoter (BCP) region affecting HBV e antigen (HBeAg) expression occur commonly and represent the predominant virus species in patients with HBeAg-negative chronic hepatitis B. The PC mutation (G1896A+C1858T) creates a translational stop codon resulting in absent HBeAg expression, whereas BCP mutations (A1762T/G1764A) reduce HBeAg expression by transcriptional mechanisms. Treatment of chronic HBV infection with lamivudine (LMV) often selects drug-resistant strains with single (rtM204I) or double (rtL180M+rtM204V) point mutations in the YMDD motif of HBV reverse transcriptase. We cloned replication-competent HBV vectors (genotype A, adw2) combining mutations in the core (wild type [wt], PC, and BCP) and polymerase gene (wt, rtM204I, and rtL180M/M204V) and analyzed virus replication and drug sensitivity in vitro. Resistance to LMV (rtM204I/rtL180M+rtM204V) was accompanied by a reduced replication efficacy as evidenced by reduced pregenomic RNA, encapsidated progeny DNA, polymerase activity, and virion release. PC mutations alone did not alter virus replication but restored replication efficacy of the LMV-resistant mutants without affecting drug resistance. BCP mutants had higher replication capacities than did the wt, also in combination with LMV resistance mutations. All nine HBV constructs showed similar sensitivities to adefovir. In conclusion, BCP-PC mutations directly impact the replication capacity of LMV-resistant mutants. PC mutations compensated for replication inefficiency of LMV-resistant mutants, whereas BCP mutations increased viral replication levels to above the wt baseline values, even in LMV-resistant mutants, without affecting drug sensitivity in vitro. Adefovir may be an effective treatment when combinations of core and polymerase mutations occur.

Novel hepatitis B virus genotype a subtyping assay that distinguishes subtype Aa from Ae and its application in epidemiological studies

The eight genotypes of hepatitis B virus (HBV) have different geographical distributions, virological characteristics, and clinical manifestations. A unique subtype of HBV genotype A (HBV/A) was reported in sub-Saharan Africa, raising the possibility that patients infected with this subtype (HBV/Aa ["a" for African and Asian]) may have different clinical outcomes than other HBV/A isolates (HBV/Ae ["e" for European]). Comparison between 30 HBV/Aa and 30 HBV/Ae isolates indicated that almost all HBV/Ae isolates had G at nucleotide (nt) 1809 and C at nt 1812, whereas HBV/Aa isolates had T1809/T1812. Taking advantage of these two single nucleotide polymorphisms (SNPs), a novel subtype-specific PCR assay in the X/precore/core region was developed. This assay was combined with a restriction fragment length polymorphism assay using BglII in a different region (nt 1984 to 1989), which has a SNP distinguishing HBV/Aa from HBV/Ae, resulting in 100% specificity for the combined assay. Application of the subtyping assay using sera from 109 paid donors in the United States indicated significantly different distributions of HBV/A subtypes among races; African-Americans, Caucasians, and Hispanics had HBV/Ae, whereas Asians had mainly HBV/Aa, suggesting that the HBV/Aa isolates may have been imported by recent immigration from Asia. In conclusion, the specificity and sensitivity of the combined subtyping assay were confirmed, and its usefulness was demonstrated in a practical context.

Acute hepatitis B virus infection in Turkey: epidemiology and genotype distribution

The aim of this study was to investigate the prevalence of hepatitis B virus (HBV) genotypes in Turkey. Epidemiological and clinical data for 158 patients with acute HBV infection from 22 medical centres in the period February 2001 to February 2002 were collected prospectively. HBV genotyping was based on analysis of restriction fragment length polymorphisms and nested PCR. There were 59 female and 99 male patients, with a mean age of 34.2 +/- 15.6 years. The most common probable transmission route was blood contact in 63 (41.1%) cases, but was unknown in 78 (49.4%) cases. The mean alanine aminotransferase level was 1718 +/- 1089 IU/L. Four of the 158 patients (2.5%) died because of fulminant hepatitis. One year after discharge, 11 (10.6%) of 103 cases were positive for hepatitis B surface antigen (HBsAg) and 80 (77.7%) were positive for anti-HBsAg. Genotype determination was unsuccessful in 11 cases because of a negative PCR; genotype D was found in the remaining 147 cases. The results suggested that acute HBV infection constitutes a significant health problem in Turkey and that genotype D is predominant.

Response to interferon-alpha in chronic hepatitis B with and without precore mutant strain detected by mutation site-specific assay

GOALS

We investigated whether the presence of precore mutant (stop codon mutation at codon 28) affects the response to interferon-alpha in patients with chronic hepatitis B.

BACKGROUND

Mutations of hepatitis B virus (HBV) may influence the response to treatment. The association of precore mutant with the response to interferon is controversial.

STUDY

Thirty-one Japanese patients with hepatitis B e antigen-positive chronic hepatitis were treated with natural interferon-alpha. HBV DNA with the precore mutation was assayed in serum using a mutation site-specific assay before and after treatment.

RESULTS

Before treatment, precore mutant was detected in 22 cases (group A) and not detected in 9 cases (group B). Serum HBV DNA level before treatment was not different between the 2 groups. At the end of treatment, serum HBV DNA was decreased to undetectable levels in 13% (4 of 31). Six months after treatment, the percentage of cases with loss of hepatitis B e antigen and a decrease in the transaminase level to within the normal range was significantly higher in group B than in group A (67%, 18%, P = 0.015).

CONCLUSIONS

Chronic hepatitis without precore mutant strain before treatment is more responsive to IFN-alpha.

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.

Mutations in the basic core promoter region of hepatitis B virus. Relationship with precore variants and HBV genotypes in a Spanish population of HBV carriers

BACKGROUND/AIMS

To determine the prevalence and significance of hepatitis B virus (HBV) basic core promoter (BCP) mutations and to establish their relationship with precore (preC) mutations, HBV genotypes and HBV-DNA levels.

METHODS

BCP and preC mutations and genotypes were determined by sequencing.

RESULTS

Genomic analysis was performed in 129 (71%) of 182 patients. BCP mutations were detected in 83% of 18 HBeAg-negative (e-) chronic hepatitis B (CHB) patients with fluctuating ALT levels, and in 76% of 58 e- CHB with elevated ALT. The prevalence was lower and similar, 55% in 30 HBeAg-positive CHB (e+ CHB) with elevated ALT and in 23 e- inactive carriers. Frequency of preC mutations was higher in e- CHB (80%) than in e- inactive carriers (65%). Among e- CHB, patients with elevated ALT and preC mutations at nt 1896 showed highest HBV-DNA, regardless of BCP mutations. BCP mutations were similar in genotypes A and D, while preC mutations were most common in genotype D (82 vs. 40%). Simultaneous presence of the main BCP (1762, 1764) and preC (1896, 1899) mutations was associated with the degree of histological injury.

CONCLUSIONS

Combined BCP and preC mutational and genotype analysis provides clinically relevant information in the study of HBV infection.

New aspects on the natural history of chronic hepatitis B infection: implication for therapy

The incidence and sequelae of chronic hepatitis B (HBV) infection appear to have been overestimated previously, especially in areas outside Asia where neonatal infection predominates. A high rate of spontaneous HBeAg seroconversion is found in children as well as adults, and 40 to 50 y of replicative infection seems to be the most important risk factor for cirrhosis and hepatocellular carcinoma necessitating a cautious attitude towards antiviral treatment. Of concern, however, HBeAg seroconversion, which usually predicts a good outcome, is not always an irreversible event. Low grade replication of HBV may continue in anti-HBe positive individuals and shift in HBe status does occur in up to 10% of viral carriers with evidence of an increased risk of complications. Viral replication (HBV DNA positivity) is also found in HBeAg negative mutant infection and is an important parameter to note. To date, the data do not suggest any different prognosis for patients with this kind of infection. Also the various viral genotypes might have different prognoses partly due to the association with precore mutations, but the present knowledge does not allow different therapeutic management as in the case of hepatitis C. Treatment is available with a number of safe antiviral agents. However, all of them are mainly suppressive with low cure rates after 1 y. Initiation of therapy should therefore mainly be considered in symptomatic chronic infection and in cases with high risk of complications i.e. patients with ongoing viral replication and age above 40 y or bridging necroses verified by liver biopsy.

Low HBeAg serum levels correlate with the presence of the double A1762T/G1764A core promoter mutation and a positive response to interferon in patients with chronic hepatitis B virus infection

OBJECTIVE

To investigate the correlation of serum hepatitis B e antigen (HBeAg) levels with the presence of core promoter (CP) mutations, hepatitis B virus (HBV) viremia and the response to interferon (IFN) in patients with chronic hepatitis B.

METHODS

Fourteen HBeAg-positive patients received alpha-2a IFN. Diluted serum samples of responders were tested for HBeAg positivity at dilutions of 1:40, 1:160 and 1:640 at the following time points: T0 (before starting IFN), T1 [at peak alanine aminotransferase (ALT) preceding HBeAg seroconversion], T2 (at ALT normalisation) and T3 (end of treatment). Nonresponder samples were similarly tested at times T0 and T3. The HBV CP and precore regions were sequenced at the same time points as for HBeAg testing.

RESULTS

Six of 14 patients (43%) responded to IFN treatment and had lower HBeAg levels than nonresponders at T0 (p = 0.003). Five of 6 responders (83%) and none of the nonresponders had the A1762T/G1764A CP mutations (0/8, p < 0.003). At T0, HBeAg was negative at the 1:640 dilution in 5 of the 6 responders, who also had lower HBV DNA levels than nonresponders (p = 0.003). During IFN treatment, HBeAg levels decreased and HBV DNA became negative at T1 in responders.

CONCLUSIONS

Low serum HBeAg and HBV DNA levels correlate with the presence of CP mutations and response to IFN treatment and can be considered as predictive markers of response to IFN.

Determinants for sustained HBeAg response to lamivudine therapy

There are inconsistent data on the durability of hepatitis B e antigen (HBeAg) seroconversion after lamivudine is discontinued. The aim of this study was to examine the determinants for sustained HBeAg response to lamivudine therapy. Both host and viral factors as well as the drug factor were compared between 43 patients with sustained HBeAg response and 39 patients whose response was not sustained. All of them received a mean period of 16 months (range, 3-55 months) lamivudine therapy and had achieved complete response (HBeAg seroconversion plus HBV DNA seroclearance by hybrid capture assay and normal alanine aminotransferase [ALT]) and were followed-up for a mean period of 44 months (range, 12-88 months). Stepwise logistic regression model was used to estimate the sustained response on the presence of the following variables: age; gender; pretherapy ALT; total bilirubin and HBV DNA levels; time to HBeAg seroconversion; additional lamivudine treatment after HBeAg seroconversion; total duration of treatment; hepatitis activity index scores; periportal, intralobular, and portal inflammation and fibrosis scores; scores excluding fibrosis; status of precore mutation; basal core promoter mutation; and genotype. The results showed that genotype (OR, 5.922; 95% CI, 1.611-21.768; P =.007), age (OR, 0.943; 95% CI, 0.891-0.997; P =.040), and additional treatment (OR, 1.097; 95% CI, 1.028-1.171; P =.005) were independent factors to sustained HBeAg response. Further categorical analysis disclosed that patients with genotype B, age < or =36 years, and additional lamivudine treatment over 8 months have higher sustained response. In conclusion, HBV genotype, age, and additional treatment are the major determinants for the sustained HBeAg response to lamivudine therapy.

Hepatitis B virus genotypes in the United States: results of a nationwide study

BACKGROUND & AIMS

Hepatitis B virus (HBV) genotypes may be related to severity of liver disease and treatment response. The aims of this nationwide study were to determine the prevalence of HBV genotypes in the United States and the association between HBV genotypes and patient demographics, mode of infection, and clinical status.

METHODS

A total of 694 consecutive chronic HBV-infected patients seen in 17 U.S. liver centers during a 1-year period were enrolled. Demographic, clinical, and laboratory data were collected. Sera were tested for HBV genotyping, precore, and core promoter variants by line-probe assays.

RESULTS

All 7 HBV genotypes (A-G) were found, with genotypes A and C the most common. The prevalence of HBV genotypes was different in different regions of the United States. A strong correlation was found between HBV genotypes and ethnicity. HBV genotype A was prevalent among white and black patients, whereas genotypes B and C were most common among Asian patients. The predominant genotype among patients born in the United States, Europe, the Far East, and Southeast Asia were A, D, C, and B, respectively. Genotypes A and C were associated with a higher prevalence of hepatitis B e antigen. Precore variant was detected in 27% of patients and core promoter variant in 44% of patients.

CONCLUSIONS

Our study suggests that the epidemiology of HBV infection in the United States may have changed over time as a result of immigration from countries with a high prevalence of HBV infection. HBV genotypes may account for the heterogeneity in disease manifestations among patients with chronic HBV infection.

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.

Hepatitis B virus genotypes and virologic response in 694 patients in phase III studies of adefovir dipivoxil1

BACKGROUND & AIMS

Hepatitis B virus (HBV) genotype may influence disease progression and antiviral response. We therefore analyzed the frequency and distribution of genotypes in patients from 2 multinational phase III studies of adefovir dipivoxil. Antiviral efficacy of adefovir dipivoxil 10-mg therapy was examined with respect to HBV genotype, hepatitis B e antigen (HBeAg) serostatus, and race.

METHODS

HBV genotypes were assigned by phylogenetic analyses of DNA sequences amplified from baseline serum samples (n = 694).

RESULTS

Patients from Asia/Oceania were infected predominantly with genotypes B and C, whereas patients from Western European countries were infected predominantly with genotypes A and D. In Mediterranean countries, genotype D was dominant. The most common genotype in North America was C, followed by A, B, and D. Regardless of location, Asian patients were infected predominantly with genotypes B or C, whereas Caucasian patients were infected predominantly with A or D. There were significant differences in the baseline serum HBV-DNA levels of patients infected with different HBV genotypes regardless of HBeAg serostatus. Forty-eight weeks of adefovir dipivoxil 10-mg therapy resulted in potent reductions in serum HBV DNA with no significant differences based on genotype, HBeAg status, or race; similarly, there was no statistical difference in HBeAg seroconversion rates between genotypes in these patients.

CONCLUSIONS

HBV genotypes were distributed asymmetrically with respect to race, geography, and HBeAg status. Forty-eight weeks of adefovir dipivoxil therapy resulted in significant decreases in serum HBV-DNA levels in patients regardless of HBV genotype, HBeAg status, or race.

Treatment of chronic hepatitis B: current challenges and future directions

The clinical management of chronic hepatitis B infection has entered a new era with the introduction and widespread use of oral nucleoside analogues such as lamivudine and nucleotides such as adefovir dipivoxil. From this, new challenges have now emerged in terms of preventing antiviral drug resistance, promoting viral clearance and improving long-term survival. For example, the natural history of nucleoside or nucleotide analogue-associated hepatitis B virus resistant mutants has yet to be determined. Furthermore, the increasing prevalence of HBeAg negative disease with its reduced response to current therapies represents an ongoing challenge to attempts to improve standard of care. There is increasing recognition of the pivotal role that viral load and genotype, and their complex interactions with the host immune response, play in determining the outcome of these treatment interventions. The purpose of this paper is to highlight several key factors that should be considered in the context of future clinical research and management of chronic hepatitis B.

Genome replication, virion secretion, and e antigen expression of naturally occurring hepatitis B virus core promoter mutants

The core promoter mutants of hepatitis B virus (HBV) emerge as the dominant viral population at the late HBeAg and the anti-HBe stages of HBV infection, with the A1762T/G1764A substitutions as the hotspot mutations. The double core promoter mutations were found by many investigators to moderately enhance viral genome replication and reduce hepatitis B e antigen (HBeAg) expression. A much higher replication capacity was reported for a naturally occurring core promoter mutant implicated in the outbreak of fulminant hepatitis, which was caused by the neighboring C1766T/T1768A mutations instead. To systemically study the biological properties of naturally occurring core promoter mutants, we amplified full-length HBV genomes by PCR from sera of HBeAg(+) individuals infected with genotype A. All 12 HBV genomes derived from highly viremic sera (5 x 10(9) to 5.7 x 10(9) copies of viral genome/ml) harbored wild-type core promoter sequence, whereas 37 of 43 clones from low-viremia samples (0.2 x 10(7) to 4.6 x 10(7) copies/ml) were core promoter mutants. Of the 11 wild-type genomes and 14 core promoter mutants analyzed by transfection experiments in human hepatoma cell lines, 6 core promoter mutants but none of the wild-type genomes replicated at high levels. All had 1762/1764 mutations and an additional substitution at position 1753 (T to C), at position 1766 (C to T), or both. Moreover, these HBV clones varied greatly in their ability to secrete enveloped viral particles irrespective of the presence of core promoter mutations. High-replication clones with 1762/1764/1766 or 1753/1762/1764/1766 mutations expressed very low levels of HBeAg, whereas high-replication clones with 1753/1762/1764 triple mutations expressed high levels of HBeAg. Experiments with site-directed mutants revealed that both 1762/1764/1766 and 1753/1762/1764/1766 mutations conferred significantly higher viral replication and lower HBeAg expression than 1762/1764 mutations alone, whereas the 1753/1762/1764 triple mutant displayed only mild reduction in HBeAg expression similar to the 1762/1764 mutant. Thus, core promoter mutations other than those at positions 1762 and 1764 can have major impact on viral DNA replication and HBeAg expression.

Effects of interferon alpha therapy on the catalytic domains of the polymerase gene and basal core promoter, precore and core regions of hepatitis B virus

AIMS

The aim of the present study was to examine the catalytic domains of the polymerase gene, the basal core promoter and the precore and core regions of the hepatitis B virus (HBV) genome for specific mutations. These may account for the response to interferon alpha (IFN-alpha) treatment, which may have prognostic value.

METHODS

Multiple serum samples were collected prospectively from 30 patients with chronic active hepatitis B who were treated with IFN-alpha. Patients were assigned to one of three groups: group A (n = 11) and group B (n = 10) individuals were hepatitis B e antigen (HBeAg)-positive prior to treatment. Group A patients underwent HBeAg seroconversion after treatment while group B patients did not. Group C (n = 9) patients were HBeAg-negative prior to treatment. The HBV DNA was extracted from the sera collected before, during and after treatment and the various genomic regions were amplified, sequenced and examined for mutations.

RESULTS

During IFN-alpha therapy, multiple changes were found in the catalytic domains of the HBV polymerase gene in all groups. The frequency of mutations and associated amino acid changes were highest in virus from group C patients and lowest in group A patients. The interdomain regions of the viral polymerase were the most affected. Multiple mutations were also found in the precore, core and core promoter regions. However, no specific mutations were associated with clinical response or outcome.

CONCLUSIONS

During IFN-alpha treatment, multiple mutations occurred in the HBV genome, including the catalytic domains of the polymerase gene. Changes that did occur could not be correlated to the clinical response or treatment outcome. However, no mutations were found that have been linked to lamivudine escape, indicating that lamivudine therapy would be effective in IFN-alpha non-responder patients.